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Fan Hangqing 《广西科学院学报》1993,(2):98-103
In the present paper,the situations concerning mangroves in Guangxi,China werereviewed with focus on resources,scientific research and natural conservation.The urgentproblems,related to coastal mangroves,were given out as some research projects for theconsiderations of foreign scientists and managers.On this basis,a favourable local study site ofmangrove ecosystem was introduced in detail. 相似文献
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Consensus of Second-Order Multi-Agent Systems with Time-Varying Delays and Antagonistic Interactions
This study investigates the consensus problem of second-order multi-agent systems subject to timevarying interval-like delays. The notion of consensus is extended to networks containing antagonistic interactions modeled by negative weights on the communication graph. A unified framework is established to address both the stationary and dynamic consensus issues in sampled-data settings. Using the reciprocally convex approach,a sufficient condition for consensus is derived in terms of matrix inequalities. Numerical examples are provided to illustrate the effectiveness of the proposed result. 相似文献
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Classical theories explaining the evolution of cooperation often rely on the assumption that the involved players are symmetrically interacted.However,in reality almost all well-documented cooperation systems show that cooperative players are in fact asymmetrically interacted and that this dynamic may greatly affect the cooperative behavior of the involved players.Here,we developed several models based on the most well known spatial game of the Hawk-Dove game,while also considering the effects of asymmetric interaction.Such asymmetric games possess four kinds of strategies:cooperation or defection of strong player and cooperation or defection of weak player.Computer simulations showed that the probability of defection of the strong player decreases with decreasing the benefit to cost ratio,and that all kinds of strategy will be substituted by cooperation on behalf of the strong player if the benefit to cost ratio is sufficiently small.Moreover,weak players find it difficult to survive and the surviving weak players are mostly defectors,similar to the Boxed Pigs game.Interestingly,the patterns of kinds of strategies are chaotic or oscillate in some conditions with the related factors. 相似文献
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We studied the evolution of cooperation in the prisoner’s dilemma game on a square lattice where the size of the interaction neighborhood is considered. Firstly, the effects of noise and the cost-to-benefit ratio on the maintenance of cooperation were investigated. The results indicate that the cooperation frequency depends on the noise and cost-to-benefit ratio: cooperation reaches a climax as noise increases, but it monotonously decreases and even vanishes with the ratio increasing. Furthermore, we investigated how the size of the interaction neighborhood affects the emergence of cooperation in detail. Our study demonstrates that cooperation is remarkably enhanced by an increase in the size of the interaction neighborhood. However, cooperation died out when the size of the interaction neighborhood became too large since the system was similar to the mean-field system. On this basis, a cluster-forming mechanism acting among cooperators was also explored, and it showed that the moderate range of the neighborhood size is beneficial for forming larger cooperative clusters. Finally, large-scale Monte Carlo simulations were carried out to visualize and interpret these phenomena explicitly. 相似文献
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In psycholinguistics, motivation and attitude have much effect on students' English study. Because there are different individuals among students, different students have different study motivations and attitudes. Directed against these individuals in tertiary colleges, we formulate different methods to help students study English well. 相似文献
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This paper considers social welfare maximization for spatial resource sharing networks(SRSNs),in which multiple autonomous users are spatially located and mutual influence only occurs between nearby users.To cope with a lack of central control and the restriction that only local information is available,a spatial resource sharing game is proposed.However,individual selfishness in traditional game models generally leads to inefficiency and dilemmas.Inspired by local cooperative behavior in biological sys- tems,a community cooperation mechanism(CCM)is proposed to improve the efficiency of the game.Specifically,when a user makes a decision,it maximizes the aggregate payoffs for its local community rather than selfishly consider itself.It is analytically shown that with the bio-inspired CCM,the social optimum of SRSNs is achieved with an exchange of local information.The proposed bio-inspired CCM is very general and can be applied to various communication networks. 相似文献
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This paper proposes an efficient framework to utilize quantum search practically.To the best of our knowledge,this is the first paper to show a concrete usage of quantum search in general programming.In our framework,we can utilize a quantum computer as a coprocessor to speed-up some parts of a program that runs on a classical computer.To do so,we propose several new ideas and techniques,such as a practical method to design a large quantum circuits for search problems and an efficient quantum comparator. 相似文献
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CHRISTOPHER X J Jensen 《科学通报(英文版)》2012,(16):1972-1981
What motivates some members of a social group to voluntarily incur costs in order to provide for the common good? This question lies at the heart of theoretical and empirical studies of cooperative behavior. This is also the question that underlies the classic volunteer’s dilemma model, which has been previously explored in scenarios where group members are related or interact asym- metrically. Here we present a model that combines asymmetry and relatedness, showing that the probability of volunteerism in such systems depends closely on both the degree of asymmetry and level of relatedness between interacting individuals. As has been shown in previous volunteer’s dilemma models, the payoff ratio and overall group size also influence the probability of volunteerism. The probability of volunteerism decreases with increasing group size or decreasing cost-to-benefit ratio of the coplayers; in the presence of asymmetrical interactions, subordinate players were more likely to offer public goods than the dominant player. More asymmetrical interactions decrease the probability of volunteerism of the dominant player; overall volunteerism increases with increasing relatedness. 相似文献
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高等教育国际化应经济全球化而生,旨在加强各国之间在教育资源方面的交流,充分利用国际教育市场,培养有国际意识、国际交往能力、国际竞争能力的人才。大连民族学院国际商学院国际化人才培养方案的设计以培养具有国际视野的应用型、复合型人才为目标,采用国际化的教学方法,引进国际合作办学模式,强化双语教学和外语教学,实施“素质+外语+专业技能”培养,以期实现高等教育人才培养的国际化跨越。 相似文献
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随着经济全球化的推进,高等教育国际化成为趋势。为进一步加快民族院校的国际化办学进程,应采取继续深化国际化办学理念;不断提高师资队伍国际化水平;构筑适合民族院校实际情况的国际化人才培养平台;广泛建立与国内外大学的合作与交流;促进与跨国企业实践方面的深层次合作,为民族地区培养急需的国际化人才。 相似文献
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Powerful expressive ability of semantic information, to be easily computed and flexibility are basic features of digital product model (DPM). Using ontology and object-oriented principle (OOP) together to cope with problems in modeling is brought forward in this paper. The two are widely used and do well in modeling, but they each alone cannot cope with all issues and new challenges. Three basic requests are pointed out in DPM modeling. Status, problems, and root of current non-semantic and semantic models are introduced. Ontology, OOP, and their difference are introduced. It is found that the two are entirely complementary with each other. How to assign the roles and to cooperate for the two in coping with the three basic issues in DPM modeling are explained in detail. 相似文献
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在网购市场繁荣的同时,传统企业也纷纷试水电子商务。传统企业具有供应链资源和品牌优势,但基于相关电子商务经验的缺乏和各方面成本等因素的考量,大多数传统企业倾向于与电子商务代运营商开展合作。电商代运营商能为传统企业提供全套电子商务网站运营解决方案,使传统企业能专注于自身核心业务。随着运营经验的积累,电商代运营商将朝着规模化、专业化的方向发展。 相似文献
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通过对框架-剪力墙结构协同工作的分析,找出了影响地震剪力分配的主要因素, 提出了确定剪力墙合理布置的基本思路和方法,为框架-剪力墙结构体系的抗震性能设计提供了参考依据. 相似文献
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The mass transfer among the multiphase interactions among the steel, slag, lining refractory, and nonmetallic inclusions during the refining process of a bearing steel was studied using laboratory experiments and numerical kinetic prediction. Experiments on the system with and without the slag phase were carried out to evaluate the influence of the refractory and the slag on the mass transfer. A mathematical model coupled the ion and molecule coexistence theory, coupled-reaction model, and the surface renewal theory was established to predict the dy-namic mass transfer and composition transformation of the steel, the slag, and nonmetallic inclusions in the steel. During the refining process, Al2O3 inclusions transformed into MgO inclusions owing to the mass transfer of [Mg] at the steel/refractory interface and (MgO) at the slag/re-fractory interface. Most of the aluminum involved in the transport entered the slag and a small part of the aluminum transferred to lining re-fractory, forming the Al2O3 or MgO·Al2O3. The slag had a significant acceleration effect on the mass transfer. The mass transfer rate (or the re-action rate) of the system with the slag was approximately 5 times larger than that of the system without the slag. In the first 20 min of the re-fining, rates of magnesium mass transfer at the steel/inclusion interface, steel/refractory interface, and steel/slag interface were x, 1.1x, and 2.2x, respectively. The composition transformation of inclusions and the mass transfer of magnesium and aluminum in the steel were predicted with an acceptable accuracy using the established kinetic model. 相似文献
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Coalfield fires are considered a global crisis that contributes significantly to environmental destruction and loss of coal resources and poses a serious threat to human safety and health. In this paper, research related to the initiation, development, and evolution of coalfield fires is reviewed. The existing detection and control techniques of coalfield fires are also reviewed. Traditional firefighting is associated with waste of resources, potential risks of recrudescence, potential safety hazards, extensive and expensive engineering works, and power shortages. Recently, coalfield fires have been recognized as having significant potential for energy conservation and heat energy recovery. Thermoelectric power generation is regarded as a suitable technology for the utilization of heat from coalfield fires. The extraction of heat from coalfield fires can also control coalfield fires and prevent reignition leading to combustion. Technologies for absorbing heat from burning coal and overlying rocks are also analyzed. In addition, the control mode of “three-region linkage” is proposed to improve firefighting efficiency. Integrating heat energy recovery with firefighting is an innovative method to control coalfield fires. 相似文献
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《矿物冶金与材料学报》2020,27(2):232-243
Nano graphene platelet (Gr) reinforced nano composites with a zinc–aluminum alloy (ZA27) matrix were produced by powder metallurgy at four different mass ratios (0.5wt%, 1.0wt%, 2.0wt% and 4.0wt%) and three different sintering temperatures (425, 450, and 475°C). In order to investigate the effect of sintering temperatures and nano graphene reinforcement materials on the composite structure, the microstructures of the composite samples were investigated and their densities were determined with a scanning electron microscope. Hardness, transverse rupture, and abrasion wear tests were performed to determine the mechanical properties. According to the test results, the porosity increased and the mechanical strength of the nano composites decreased as the amount of nano graphene reinforcement in ZA27 increased. However, when the composites produced in different reinforcement ratios were evaluated, the increase in sintering temperature increased the mechanical structure by positively affecting the composite structure. 相似文献
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《矿物冶金与材料学报》2020,27(7):933-942
A high-building multi-directional pipe joint (HBMDPJ) was fabricated by wire and arc additive manufacturing using high-strength low-alloy (HSLA) steel. The microstructure characteristics and transformation were observed and analyzed. The results show that the forming part includes four regions. The solidification zone solidifies as typical columnar crystals from a molten pool. The complete austenitizing zone forms from the solidification zone heated to a temperature greater than 1100°C, and the typical columnar crystals in this zone are difficult to observe. The partial austenitizing zone forms from the completely austenite zone heated between Ac1 (austenite transition temperature) and 1100°C, which is mainly equiaxed grains. After several thermal cycles, the partial austenitizing zone transforms to the tempering zone, which consistes of fully equiaxed grains. From the solidification zone to the tempering zone, the average grain size decreases from 75 to 20 μm. The mechanical properties of HBMDPJ satisfies the requirement for the intended application. 相似文献
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《矿物冶金与材料学报》2020,27(9):1251-1258
A Monte Carlo Potts model was developed to simulate the recrystallization process of a cold-rolled ultra-thin grain-oriented silicon steel. The orientation and image quality data from electron backscatter diffraction measurements were used as input information for simulation. Three types of nucleation mechanisms, namely, random nucleation, high-stored-energy site nucleation (HSEN), and high-angle boundary nucleation (HABN), were considered for simulation. In particular, the nucleation and growth behaviors of Goss-oriented ({011}<100>) grains were investigated. Results showed that Goss grains had a nucleation advantage in HSEN and HABN. The amount of Goss grains was the highest according to HABN, and it matched the experimental measurement. However, Goss grains lacked a size advantage across all mechanisms during the recrystallization process. 相似文献