Experimental Study on the Influencing Factors of Motion Responses on an Air-Floating Caisson with Multiple Compartments

The structure of an air-floating caisson is suitable for the major structure of caisson-type artificial islands.Thus,it has been rapidly developed and widely used in the exploration and development of oil and gas fields in shallow sea and intertidal zones.Air-floating transportation technology is one of the key technologies employed in this structure.In this paper,the factors influencing the dynamic response characteristics of air-floating caisson with multi-compartments(AFCMC)were studied using model tests.The length and the height of each air-floating structure in the model were 1.0 and 0.1 m,respectively.In addition,the 1:100 models with 6,8,and 10 compartments under regular waves were tested in the wave flume,respectively.In the experiments,the respective water depths were set at 0.2,0.3,and 0.4 m,and the corresponding drafts were 0.05,0.06,and 0.07 m.Results show that with the increase of draft,the heave natural period increased and the maximum amplitude of the heave motion decreased.Meanwhile,the pitch motion decreased at 6 and 8 compartments and increased at 10 compartments.As the water depth increased,the maximum amplitude and amplitude change of heave and pitch motions first increased and then decreased.However,several amplitudes close to the maximum amplitude appeared in the measured period at shallower water depth,thereby indicating the vertical movements of the structure enhanced under shallow water.The increase in the number of compartments reduced the vertical movements under 6.0 m draft,but it increased the vertical movements under 5.0 and 7.0 m draft.Thus,increasing the number of compartments has a limited capacity to improve the motion performance of the structure.     

Towards sustainable mining cities: what policies should be sought and experiences could be learnt for China?

Foundationitem:UndertheauspicesoftheNationalNaturalScienceFoundationofChina(No.49601007)1IntroductionThehlemelineoftilepaperisanexPlorahonofthetenns'sustainablecihes',whichweremuchinevidCnceatHabitatIIheldatIStanbulinJunel996(UNCHtheUnitedNationConferenceonHumanSettlements).ttisexPlorahoniscompletelynottotracethefashionofthewordsthemselves,rathertoviewthefactSthat,ontheonehand,IniningciheshavebeenplaytngsuchacrucialroletoChina'snahonalsocio-economyasChinahasbeingcontributedtotheglob…     

藏西北多龙矿集区拿若斑岩铜（金）矿床磷灰石矿物学特征及地质意义

拿若矿床目前是藏西北改则县多龙矿集区第三大斑岩型铜（金）矿床,前人开展了系统的成岩成矿年代学、成矿地质背景等研究,但空间蚀变分带和岩浆演化过程等方面研究较为薄弱。笔者等以拿若矿床磷灰石作为研究对象,在大量钻孔科研编录的基础上,开展了磷灰石矿物学和矿物化学研究,探讨拿若矿床磷灰石矿物彩色阴极发光特征与蚀变分带的耦合关系,揭示含矿岩浆演化期次及氧化还原状态。磷灰石彩色阴极发光特征显示,拿若矿床磷灰石彩色阴极发光（CL）特征主要表现为黄褐色、绿色—亮黄色和灰黑色,分别对应未蚀变、钾化蚀变和绢英岩化蚀变环境,磷灰石彩色CL特征与其所处蚀变环境的关系验证了笔者等重新厘定的拿若矿床斑岩系统“双钾化带”空间蚀变分带结构。磷灰石电子探针（EPMA）主量元素测试结果显示,磷灰石的CaO = 53. 5%~56. 5%,P2O5 = 39. 5%~42%,F = 1. 26%~3. 24%,Cl = 0. 01%~1. 99%,SO3 = 0~1. 28%,由此计算的XF = 0. 68~1. 76,XCl = 0. 001~0. 58,XOH = 0. 21~1. 05。不同类型、阶段的磷灰石挥发分（F、Cl、OH）、SO3等成分含量变化趋势反映了拿若矿床岩浆—热液演化过程发生了气体饱和流体出溶金属沉淀的过程,并揭示了成矿岩浆高氧逸度的性质。此外,环带状岩浆磷灰石反映了隐爆角砾岩系统发育了三期次岩浆作用,并指示了第I、III期岩浆活动具有更高氧逸度特征,与成矿关系更加密切。因此,笔者等认为在多期次岩浆热液叠加型斑岩铜矿床中,磷灰石在辅助厘定蚀变类型和反演岩浆—热液演化过程中具有重要的价值。     

Community structure of picoplankton abundance and biomass in the southern Huanghai Sea during the spring and autumn of 2006

During spring and autumn of 2006,the investigations on abundance,carbon biomass and distribution of picoplankton were carried out in the southern Huanghai Sea(Yellow Sea,sHS) . Three groups of picoplankton-Synechococcus(Syn) ,Picoeukaryotes(PEuk) and heterotrophic bacteria(BAC) were identified,but Prochlorococcus(Pro) was undetected. The average abundance of Syn and PEuk was lower in spring(5.0 and 1.3 × 10 3 cells/cm 3,respectively) than in autumn(92.4 and 2.7 × 10 3 cells/cm 3,respectively) ,but it was opposite for BAC(1.3 and 0.7 × 10 6 cells/cm 3 in spring and autumn,respectively) . And the total carbon biomass of picoplankton was higher in spring(37.23 ± 11.67) mg/m 3 than in autumn(21.29 ± 13.75) mg/m 3 . The ratios of the three cell abundance were 5:1:1 341 and 30:1:124 in spring and autumn,respectively. And the ratios of carbon biomass of them were 5:7:362 and 9:4:4 in spring and autumn,respectively. Seasonal distribution characteristics of Syn,PEuk,BAC were quite different from each other. In spring,Syn abundance decreased in turn in the central waters(where phytoplankton bloom in spring occurred) ,the southern waters and inshore waters of the Shandong Peninsula(where even Syn was undetected) ;the high values of PEuk abundance appeared in the central and southern waters and the inshore of the Shandong Peninsula;the abundance of BAC was nearly three order of magnitude higher than that of photosynthetic picoplankton,and high values appeared in the central waters. In autumn,Syn abundance in central waters was higher than that in surrounding waters,while for PEuk abundance,it decreased in turn in the inshore waters of the Shandong Peninsula,the southern waters and the central waters;BAC presented a complicated blocky type distribution. Sub-surface maximum of each group of picopalnkton appeared in both spring and autumn. Compared with the available literatures concerning the studied area,the range of Syn abundance was larger,and the abundance of BAC was higher. In addition,the conversion factors for calculating picoplanktonic carbon biomass were discussed,with the conversion factors which are different from previous studies in the same surveyed waters. The result of regression analysis showed that there was distinct positive correlation between BAC and photosynthetic picoplankton in spring(r=0.61,P 0.001) ,but no correlation was found in autumn.     

东秦岭印支期成矿作用及其地质意义

秦岭造山带是中国大地构造的关键部位,经历了长期的演化历史,并于印支期最终完成拼合,由此转入燕山期陆内造山阶段.印支期是东秦岭地区构造体制转换的关键时期,这一时期形成了规模宏大的以I型为主要特征的花岗岩类.众多与印支期花岗岩类成矿作用密切的钨钼铜金等矿床同位素数据表明,中生代是秦岭成矿带最重要的成矿时期,华北地块南缘—南...     

Fractal Characteristics of Shale Reservoir Based on the High-pressure Mercury Injection Method

<正>1 Introduction Shale of continental basin of east China general is a product of lake face,from shallow lake to deep lake.It is also a good cap rock to prevent oil and gas emission.The shale generally has bigger special surface area,its pore is small,its structure is complex,and it is easy to absorb water,     

Study on Seepage Characteristics of Composite Bucket Foundation Under Eccentric Load

Under the effect of eccentric loads,when the suction pressure of the composite bucket foundation is leveled,the seepage failure is very easy to occur.The seepage failure occurrence causes the foundation to settle unevenly and impairs the bearing performance.This study uses ABAQUS finite element software to establish a composite bucket foundation model for finite element analysis.The model simulates the seepage of the foundation penetrating process under eccentric load to reveal the induced seepage characteristics of the bucket foundation.The most vulnerable position of seepage failure under the eccentric loading is elucidated.Critical suction formulas for different offset eccentric moment strategies are derived and compared with existing literature formulas.Then the derived formula is supplemented and corrected according to the pressure difference between adjacent cabins.Conclusions can be drawn:(1)Under eccentric loads,the critical suction decreases about 7%?10%.(2)The pressure difference between adjacent cabins impacts significantly on the seepage field,and the critical suction,at most,can be reduced by 17.56%.(3)the offset strategies have little effect on the seepage field.Efficient and appropriate strategies can be selected to meet the requirement of leveling in engineering project.     

HCO emission from H II-molecular cloud interface regions

A survey of well-known molecular clouds in the four strongest HCO NK-,K+ = 1(01)-0(00) hyperfine transitions has been carried out to determine the prevalence of HCO and to study its chemistry. HCO emission was observed in seven molecular clouds. Three of these, NGC 2264, W49, and NGC 7538, were not previously known sources of HCO. In addition, NGC 2024 and Sgr B2 were mapped and shown to have extensive HCO emission. The survey results show the HCO abundance to be enhanced in H II-molecular cloud interface regions and support a correlation between C+ and HCO emission. The strength of the HCO emission in NGC 2024 is interpreted in terms of this enhancement and the source structure and proximity to Earth.