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1.
The prediction theories for complex systems with a hierarchial structure and their applications to the climate process are a significant and forward-looking field of research.However,up to the present,they are yet not known and understood very well. This paper presents a preliminary theoretical frame for them.As a normal example,the basic behaviors and the dynamic strructure of the climate system are discussed in detail.The conclusions indicate that the climate system may be considered as a cascade of several subsystems located in different hierarchies.Such a dynamic structure is just the cause resulting in the nonstationarity.The conclusions also indicate that the main barrier of the climate prediction in theory derives from the contrary between the stationarity hypothesis for the current prediction theory and the nonstationary behavior of the real climate process.In addition,some work is disussed for detecting the nonstationarity in climate and other geophysical data and predicting the nonstationary process developed in recent years.These works may construct a preliminary base for applying to the climate predictions.  相似文献   

2.
崔文  玄忠波 《科技信息》2012,(30):224-225
CDTF-Library is a library in Chinese-German Technical Faculty of Qingdao University of Science and Technology in Qingdao.The library was established in the spring of 2004.The CDTF-Library is very small in scale.For our limited budget,the best solution to solve the problems is to expand the library to an e-library on the Internet.So I decided to collect German resources from internet at first,and set up a website for the readers as the subject for the practical customer service project design.At the same time I set up a chat room as an advertisement for the e-library.In the chat room played back audio and video materials what the e-library have.  相似文献   

3.
游荣荣 《科技信息》2011,(9):I0231-I0231,I0417
This thesis aims to contrast the taboos between China and English-speaking countries,in order to make people know and understand the taboos in public activities.It is helpful for our cross-cultural social intercourse and makes both sides to understand each other’s real intention correctly.It can remove all kinds of obstacles in international communication of the world.  相似文献   

4.
The behaviors of helium in vanadium including stability,diffusion,and its interaction with vacancy as well as its effects on the ideal tensile strength was investigated by a frst-principles method.The activation energy barrier of helium was calculated to be 0.09 eV,which is consistent with the experimental result.The results indicated that the vacancy can lead to a directed helium segregation into the vacancy to form a helium cluster since the vacancy provides a "lower atomic and electron density region" as a large driving force for helium binding.It is easy for a mono-vacancy to trap helium and form a Hen V complex.The frst-principles computational tensile test demonstrates that helium obviously decreased the tensile strength of vanadium.  相似文献   

5.
Numerical weather prediction (NWP) has become one of the most important means for weather forecasts in the world. It also mirrors a nation's comprehensive strength in meteorology. In 2000, China Meteorological Administration (CMA) established the National Innovative Base for Meteorological Numerical Prediction in the Chinese Academy of Meteorological Sciences (CAMS), to work on developing a new generation of the national operational NWP system-Global/Regional Assimilation and PrEdiction System (GRAPES), to enhance meteorological services in China in the new century. In recent years, the GRAPES has witnessed a fast development. The GRAPES has been set up as an integration of the model framework, data assimilation, regional and global NWP system, which can be commonly used for both operation and research. In this paper, a brief review is made for illustrating the GRAPES system, including the advanced designs of the GRAPES, its diverse applications in multi-fields, and efficiencies of the regional and global GRAPES in operational applications based on hindcast results.  相似文献   

6.
The high-priced and limited Pt constitutes a high barrier to commercialization of fuel cells. Pt is essential for the electrode catalyst of polymer electrolyte fuel cells (PEFCs). A reduction in Pt usage is one of the key requirements for the commercialization of fuel cells for use in everyday life, because of its high price and limited availability, and the difficulty of finding suitable substitutes. Non-Pt fuel cell catalysts will decrease the demand for Pt by PEFCs, enabling more Pt to be available for use in other essential products, and make fuel cells more popular. The cheaper Mo2C is known to possess similar catalytic activities and electronic structures to Pt. Carbon black (CB) is widely used as the support for Pt nanoparticles. However,  相似文献   

7.
Silver in the form of AgNO3 was added to ZnO-based varistor ceramics prepared by the solid-state reaction method.The effects of AgNO3 on both the microstructure and electrical properties of the varistors were studied in detail.The optimum addition amount of AgNO3 in ZnO-based varistors was also determined.The mechanism for grain growth inhibition by silver doping was also proposed.The results indicate that the varistor threshold voltage increases substantially along with the AgNO3 content increasing from 0 to 1.5mol%.Also,the introduction of AgNO3 can depress the mean grain size of ZnO,which is mainly responsible for the threshold voltage.Furthermore,the addition of AgNO3 results in a slight decrease of donor density and a more severe fall in the density of interface states,which cause a decline in barrier height and an increase in the depletion layer.  相似文献   

8.
The wear of cutting tools in the machining of 2024Al alloy composites reinforced with Al2O3 particles using varying sizes and volume fractions of particles up to 23.3vol% was investigated by a turning process using coated carbide tools K10 and TP30 at different cutting speeds. Machining tests were performed with a plan of experiments based on the Taguchi method. The tool life model was developed in terms of cutting speed, size, and volume fraction of particles by multiple linear regressions. The analysis of variance (ANOVA) was also employed to carry out the effects of these parameters on the cutting tool life. The test results show that the tool life decreases with the increase of cutting speed for both cutting tools K10 and TP30, and the tool life of the K10 tool is significantly longer than that of the TP30 tool. For the tool life, cutting speed is found to be the most effective factor followed by particle content and particle size, respectively. The predicted tool life of cutting tools is found to be in very good agreement with the experimentally observed ones.  相似文献   

9.
Based on the Naviev-Stokes equations and the standard κ-ε turbulence model, this paper presents the derivation of the governing equations for the turbulent flow field in a draft tube. The mathematical model for the turbulent flow through a draft tube is set up when the boundary conditions, including the inlet boundary conditions, the outlet boundary conditions and the wall boundary conditions, have been implemented. The governing equations are formulated in a discrete form on a staggered grid system by the finite volume method. The second-order central difference approximation and hybrid scheme are used for discretization. The computation and analysis on internal flow through a draft tube have been carried out by using the simplee algorithm and cfx-tasc flow software so as to obtain the simulated flow fields. The calculation results at the design operating condition for the draft tube are presented in this paper. Thereby, an effective method for simulating the internal flow field in a draft tube has been explored.  相似文献   

10.
<正>In order to meet the strict requirements for information in engineering management,the positive interval (0,1]in Shannon information entropy is extended to the real number interval[- 1,1].The information theory and the decision theory are combined effectively,and the deficiencies that the traditional Bayes decision-making methods only consider a single factor are made up for.The multi-factors engineering decision-making methods are proposed,and some critical problems are solved in the practical engineering management decision-making process.  相似文献   

11.
The barrier/seed layer is a key issue in Through Silicon Via (TSV) technology for 3-D integration. Sputtering is an important deposition method for via metallization in semiconductor process. However, due to the limitation of sputtering and a "scallop" profile inside vias, poor step coverage of the barrier/seed layer always occurs in the via metallization process. In this paper, the effects of several sputter parameters (DC power, Ar pressure, deposition time, and substrate temperature) on thin film coverage for TSV applications are investigated. Robust TSVs with aspect ratio 5 : 1 were obtained with optimized magnetron sputter parameters. In addition, the influences of different sputter parameters are compared and the conclusion could be used as a guideline to select appropriate parameter sets.  相似文献   

12.
Tundish is the last refractory vessel in the steelmaking process. The fluid flow phenomena in tundish have a strong influence on the separation of non-metallic inclusions. The dispersive bubble wall (DBW) is a new method in tundish metallurgy. A water model of a multi-strand tundish has been set up based on the Froude number and Reynold number similarity criteria. The effect of DBW+weir on the flow pattern has been studied. The results show that this new structure of DBW+weir is beneficial not only to uniform the temperature among different submerge entry nozzles but also to separate non-metallic inclusions from liquid steel. The DBW can capture the particles of non-metallic inclusions and make them float up to the surface.  相似文献   

13.
The magnesium alloy grew in a fashion of cellular crystals during the process of unidirectional solidification, and the {0001} crystal face orientation in the cast ingot of the magnesium alloy was studied. The theoretical model and methodology were set up, and a corresponding experiment was carried out to verify the theoretical analysis results. The experimental results indicate that the {0001} crystal face of magnesium crystals parallels to the width direction for the thin-plate cast ingot when the magnesium grows in a manner of cellular crystals. The separation angle between the {0001} crystal face of magnesium crystals and the vertical axis line of the cast ingot is about 62° for the circular column cast ingot, which distributes in cone-type. The theoretical analysis results are basically in agreement with the experimental ones of previous literatures and this paper.  相似文献   

14.
吴晓娟 《科技信息》2011,(22):I0156-I0157
As we all know,some Chinese idioms are very different from English idioms in their constitutions and the figurative usages.How to comprehend and translate those idioms is a troublesome problem for most children.This paper will help you to make a successful translation.This paper falls into three parts.The first part,gives a brief introduction about the features of idioms.The second part gives a detailed introduction about how to retain those character in translation and the methods of translating idioms.And finally,it sums up several problems which we should pay attention to in translating idioms.  相似文献   

15.
Based on circular economy and sustainable manufacture theories, the drawbacks in the existing quality management models are analyzed. The requests that satisfy the big system "environment-society-economy" are summarized to build up a model. A Chinese traditional cultural principle is applied and the relevant contents are sublimated as the platform to set up the model. The new quality management concept models are put forward: "T-D-R" three dimension structures and "ecological quality loop" model, from which the new quality concepts are formed. The paper elaborates the contents and the process of setting up the models. The big system quality problems can be handled by the new quality concept and model that are validated in practice.  相似文献   

16.
Considering the characteristic of selective heating of microwave and the treatment of titania-bearing BF slag, a mathematical model for the heating of a slag specimen is developed. The temperature distribution in the specimen is studied by numerical simulation. The temperature in the center of the cylindrical slag specimen is the highest and the temperature decreases when the radius increases rapidly. In this case, the temperature rising rate decreases with heating time rapidly, and it tends to zero when the heating time is up to 150 s.  相似文献   

17.
《矿物冶金与材料学报》2020,27(8):1036-1045
Small-particle interlayers (lenticles) show some characteristic hydraulic properties and can affect the movement of unsaturated water. In this study, we developed a novel online capillary-water-absorption monitoring device and conducted three groups of comparison tests to simulate lenticle positions and thicknesses with respect to the capillary rise. The results show that the characteristic wetting front exhibits a fast rise in the early stage, a slow rise in the middle stage, and stability in the later stage. The motion of the capillary water in the lenticle is mainly transversal, with the upward curve being “flat,” and the longer is “flat,” the longer is the time needed for the water to move. The interlayer can form a capillary stagnation zone with moisture content close to saturation. The high interlayer may form a discontinuous corrugated capillary zone. Thus, when the wetting front reaches the “coarse-grain (lower)?fine-grain (upper)” interface, the “anti-capillary barrier effect” results in more moisture in the upper layer. Thus, when the wetting front of the capillary water reaches the “fine-grain (upper)?coarse-grain (lower)” interface, the “capillary barrier effect” causes the moisture content of the upper tailings to decreases sharply because of the horizontal movement of the water in the fine medium. It is clear that the presence of lenticles can retard the rise of capillary water by storing water.  相似文献   

18.
In twisting a yarn running over a guide surface, the twist inserted into the part in front of the guide is impeded to transmit freely to the part behind the contact zone. A new device has been set up for investigating twist blockage and yarn torque - twist simultaneously. Measurements of twist blockage in relationship to different parameters have been carried out by using a monofilament yarn and a multifilament yarn. The factors under consideration include the wrap angle, yarn tension and input twist.  相似文献   

19.
Thermal energy storage (TES) can increase the energetic efficiencies and, in many cases, the exergetic efficiencies of thermal energy systems. Steam boiler plant with a violently fluctuating load is a typical example when a steam accumulator is added to it. While the comparatively big first cost constitutes a barrier to the wide use of TES, the cost will notably be reduced through minimizing the necessary thermal capacity of it. The structure and illustrations are given for the computer program designed for performing the optimization. This program was applied to an existing boiler plant equipped with a steam accumulator. The results show that there would have been a big reduction in the necessary capacity, if the design of this steam accumulator had been optimized. Four conclusions have been reached.  相似文献   

20.
The nature of zero-knowledge is re-examined and the evidence for the following belief is shown:the classic simulation based definitions of zero-knowledge(simulation zero-knowledge)may be somewhat too strong to include some "nice" protocols in which the malicious verifier seems to learn nothing but we do not know how to construct a zero-knowledge simulator for it.To overcome this problem a new relaxation of zero-knowledge,reduction zero-knowledge,is introduced.It is shown that reduction zero-knowledge just lies between simulation zero-knowledge and witness indistinguishability.Under the assumption of existence of one-way permutations a 4-round public-coin reduction zero-knowledge proof system for NP is presented and in practice this protocol works in 3 rounds since the first verifier's message can be fixed once and for all.  相似文献   

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