Experimental evaluation of biases associated with sampling estuarine fishes with seines

Beach seines are widely used to estimate the density and species richness of fishes in estuaries. We evaluated the causes and extent of bias in estimates from seines using a series of field experiments in small estuaries in southern California, USA. Seining in spatially paired areas that were either enclosed by block nets or not, revealed that seines used without block nets und erestimated density by more than 4-fold and species richness by more than 2-fold relative to blocked areas. Seining in paired blocked areas with seines of two lengths revealed that net length affected estimates of density, but not species richness; a 7.6-m long seine produced 1.6-fold higher estimates of total density than did a 15.2-m long seine due to increased catches of demersal fishes, but not midwater species. Paired sampling in blocked areas also revealed that many fishes initially evaded capture by the seine. Estimates of density but not species richness were significantly higher in areas through which a seine was swept 5 times compared to once. This was due to higher catches of demersal fishes but not midwater fishes in areas seined 5 times. Repeated seining through blocked areas revealed that the vast majority (90% or more) of species and individuals of midwater fishes were captured within the first 5 sweeps, compared to only about 50% of the individuals of demersal species. A mark-recapture study in blocked areas revealed lower probabilities of capture for demersal species relative to midwater species.     

含不同半径孔洞的颗粒体模型的力学行为数值模拟

本文通过编程建立了非连续介质(颗粒体材料)模型,采用FLAC软件模拟了静水压力条件下不同半径的巷道围岩中的剪切应变增量、最小主应力及最大主应力的分布规律。研究表明,随着孔洞半径的增大,呈圆环形的剪切应变增量与最小主应力的高值区的圈数、呈辐射状的最大主应力的高值区的延伸范围及剪切应变增量的最大值都呈先慢后快的增长趋势。模型中最大的拉应力接近于在模型四周所施加的压应力,而最大的压应力约为所施加的压应力的5～10倍。模型内部的剪切应变增量、最小主应力及最大主应力的分布是高度不均匀的。具有较高的差应力的位置与具有较高的剪切应变增量的位置具有很好的一致性。     

Kriging with strings of data

The concept of a random function and, consequently, the application of kriging cells for the implicit assumption that the data locations are embedded within an infinite domain. An implication of this assumption is that, all else being equal, outlying data locations will receive greater weight because they are seen as less redundant, hence, more informative of the infinite domain. A two- step kriging procedure is proposed for correcting this siring effect. The first step is to establish the total kriging weight attributable to each string. The distribution of that total weight to the samples in the string is accomplished by a second stage of kriging. In the second stage, a spatial redundancy measure r_(n) is used in place of the covariance measure in the data-data kriging matrix. This measure is constructed such that each datum has the same redundancy with the (n)data of the string to which it belongs. This paper documents the problem of kriging with strings of data, develops the redundancy measure r_(n),and presents a number of examples.     

Kriging with strings of data

The concept of a random function and, consequently, the application of kriging cells for the implicit assumption that the data locations are embedded within an infinite domain. An implication of this assumption is that, all else being equal, outlying data locations will receive greater weight because they are seen as less redundant, hence, more informative of the infinite domain. A two- step kriging procedure is proposed for correcting this siring effect. The first step is to establish the total kriging weight attributable to each string. The distribution of that total weight to the samples in the string is accomplished by a second stage of kriging. In the second stage, a spatial redundancy measure r_(n) is used in place of the covariance measure in the data-data kriging matrix. This measure is constructed such that each datum has the same redundancy with the (n)data of the string to which it belongs. This paper documents the problem of kriging with strings of data, develops the redundancy measure r_(n),and presents a number of examples.     

Intercalation of kaolinite with acetamide

Upon intercalation of both ordered (low defect) and disordered (high defect) kaolinites with acetamide, two types of interaction are observed. Firstly, hydrogen bonding between the NH₂ groups of the acetamide with the siloxane oxygens is formed, as evidenced by the formation of two new bands at 3400 and 3509 cm^–1. Secondly, the appearance of additional bands at ∼3600 cm^–1 in both the infrared and Raman spectra of the acetamide intercalates is attributed to a second type of hydrogen bonding by the interaction of the C=O group and the inner surface hydroxyls. Changes in the intensity of the hydroxyl deformation modes in the 895 to 940 cm^–1 region are attributed to the changes in the hydrogen bonding of the kaolinite surfaces. It is proposed that the hydrogen bonding between the adjacent kaolinite layers is replaced with hydrogen bonding between both kaolinite surfaces and the acetamide molecule. Changes in the molecular structure of acetamide are observed upon intercalation. The amide 1 band is lost and replaced with a well-defined NH₂ deformation vibration. The loss of the amide 1 band is attributed the hydrogen bond formation between the amide hydrogens and the siloxane surface. The bands of the C=O group at 1680 and 1740 cm^–1 become a single band at 1680 cm^–1. The amide 2 band remains unchanged. The lack of intensity of the 1740 cm^–1 band is attributed to the formation of hydrogen bonding between the inner surface hydroxyl groups and the carbonyl group. Received: 4 February 1998/ Revised, accepted: 30 June 1998     

Decarbonation of geothermal waters by seeding with aragonite crystals coupled with air bubbling

During the cooling of the geothermal water of Chott El-Fejjej (Tunisia), considerable scaling occurred in the inlet to the tower. To attempt to resolve this problem, decarbonation (CaCO₃ precipitation) induced by seeding, with aragonite crystals recovered on site, coupled with air bubbling has been studied. The advantage of this new technique is that no chemical addition is needed and a large volume of sludge is avoided. Attention is paid to seeding time, airflow rates and amount of seed added. Experimental results indicate that crystallisation takes place on seed crystals; consequently, precipitation on the wall of the reactor is prevented. The seeding which accelerates the precipitation, that is dependent on the physico-chemical properties of the water, should be curried out at the earliest possible stage for instantaneous precipitation. A threshold for air bubbling, beyond which no improvement appeared is observed. The kinetics of the secondary germination are dependent on supersaturation of water, the airflow rate and the amount of added seed.     

融化作用下多年冻土隧道围岩的弹塑性解及其与支护的相互作用分析

多年冻土隧道修建中,施工活动产生的热量将导致多年冻土围岩中出现一定范围的融化圈,进而影响支护的受力以及隧道洞室的收敛。将围岩分为融化区和未融化区,将融化区围岩视为弹塑性介质,未融化区围岩视为弹性介质,建立并求解融化作用下多年冻土隧道围岩弹塑性模型,对不同的围岩条件及支护工况下多年冻土段隧道施工中围岩与支护的相互作用进行分析。结果表明,该模型表现了融化作用下多年冻土围岩与支护相互作用的特征;在较差围岩中,喷射混凝土支护的强度是控制融化作用下多年冻土围岩稳定以及隧道周边位移量的关键因素。在多年冻土隧道施工中,可采用本模型确定施工中容许的最大围岩融化深度,施工中应采取有效措施避免围岩中出现过大的融化圈。     

多物源条件下的储层地质建模方法

濮城沙三中油藏具有两个主物源,分别为NE向与SE向。油藏数值模拟需要在一套地质网格中对其进行模拟。经典的地质统计学利用变差函数描述区域化变量的空间几何结构特性。变差函数的计算是基于两点进行统计的,对其描述主要涉及方位角、变程、块金值和基台值。为了在一套模拟网格中模拟出多个物源条件下储层的分布特征,必须在不同的位置设置不同的变差函数参数。文中给出了两种方法实现这一目的:一是采用人为分区,把不同物源影响的区域分成不同的区块,分别对不同的区块设置不同的变差函数参数;二是采用变方位角,即根据不同的位置设置不同的变差函数方位角。这两种方法都实现了在一套网格中模拟具有多个物源方向的储层分布,更真实地再现了储层的空间展布特征。     

铁山隧道病害治理技术

巴鼓公路铁山隧道全长2099m、由于受煤层采空区，地下水及软弱围岩等因素的影响，致使K140＋527－608段二次衬砌出现开裂、错台、掉块、水沟断裂、渗水、危及行车安全、被迫关闭交通，进行病害整治。重点介绍了病害整治过程中的结构拆除控制爆破和采空区注浆加固技术。     

真空-堆载联合预压处理软基效果的室内试验研究

对甬-台-温高速公路采用真空-堆载联合预压处理软基前后的土样进行了室内试验分析,得出了合理的试验结论,即土的物理性质指标分别得到不同程度的降低,强度指标得到较大的提高。     

The association of gold with calcrete

The discovery that Au accumulates in calcrete (pedogenic carbonate or caliche) was made in 1987 by CSIRO. Calcrete is a general term describing accumulation of alkaline earth metals in soils of arid and semi-arid terrains around the world. The principal constituent of calcrete is calcite while Au is a noble metal. Calcrete has been a significant tool in a number of Au deposit discoveries, so understanding the mechanisms by which these diametrically different components come together is valuable for enhancing future discovery. Numerous laboratory experiments, case histories and exploration models have been published (most from Australia) yet we do not fully understand the mechanisms involved. It is timely, therefore, twenty-five years on since the first publication of this phenomenon, to review this highly unusual but economically important association.Critical to any review on Au in calcrete is to first consider calcretes themselves. The nature of a particular calcrete, where it has formed and mode of formation is relevant to how, where and why Au accumulates within it. This review commences with a background, nomenclature, history, classification and some examples of calcrete types found near Au deposits. How calcretes form, their origins and the role of biota is considered. Their locations in the regolith and landscape, as well as exploration models for Au in calcrete are discussed. A section on the chemistry of Au in calcretes details what we know about possible mechanisms of formation and considers what laboratory experiments on microorganisms and abiotic experiments tell us. Following on is a summary of practical aspects of identifying, collecting and analysing samples for exploration purposes. Selected mineral exploration case histories are described and how they fit into models of exploration and different regolith settings. Concluding sections include a summary and implications of this accumulated knowledge to discovering Au deposits.     

微生物灌浆加固土体研究进展

水泥和化学浆材是土体加固中最为常用的胶凝材料,但由于存在着高能耗、高污染排放和高成本等缺点而限制了它们的应用。微生物灌浆加固技术是最近发展起来的一种新型的土体加固方法,通过向松散砂土中灌注菌液以及营养盐,利用微生物矿化作用在砂颗粒间快速析出方解石凝胶,改善土体的物理力学性质。系统总结了国内外关于微生物灌浆加固土体的室内及现场试验研究,同时对固化土体的工程特性、原位无损测试方法以及灌浆效果的影响因素等进行了论述。研究表明,微生物灌浆技术具有施工扰动小、灌浆压力低、环境友好等优势,并可显著提高土体的强度、刚度及抗液化性能,在土体加固领域有着非常广阔的应用前景,但关于微生物固化土体的耐久性以及灌浆的经济性等问题仍需进行深入的探讨与研究。     

Interaction of Stress Waves with Crack

The shock of stress waves causes deformation in intact medium, the form of new cracks and finally the failure in the material. The preexisting cracks not only help increase fracture efficiency but also absorb the energy of the stress wave to induce a decay of its propagation. Therefore the study of interaction of Stress waves with cracks will greatly contribute to the interpretation of blasting mechanism, the stress wave propagation and the dynamic behaviour of material. Our emphasis is laid on interaction of stress wave with cracks, and the influence of cracks on attenuation of the wave propagation. A view is made of the current state of model calculation and experimental technique carried out in this field.     

The wave equations for oscillator with Planck's constant and with a quantum of force

The model of oscillator with mass m is considered. The expression for potential energy of oscillator U = mω²x²/2 is symmetric with respect to angular frequency ω and coordinate x. Provided that in case of small ω not the mechanical angular momentum mωx², but the force mω²x is quantizied, a wave equation of mass motion is examined. This wave equation contains a quantum of force and is examined in ω-space. Such an equation is similar to the Schrodinger equation for harmonic oscillator with Planck's constant in x-space. The wave equation with quantum of force gives the spectrum of values of oscillator energies E_n = Hx(n+1/2), where H is the quantum of force, n = 0,1,2,…. Theoretical estimate for gravitation force quantum H is 10⁻³⁷ ÷ 10⁻³⁶ N. A few results of observational cosmology can be explained by quantization of force. The model presented permits one to link directly the Newton's laws of classical mechanics and the quantum theory. Moreover, such an approach allows one to explain the frequency steps of quantum standards and also irregular globally-correlated frequency variations of standards.     

Statistics of Stars with Relativistic Velocities

The scenario for the dynamical capture of a binary system in the neighborhood of a supermassive black hole used byHills in 1988 to predict the existence of hypervelocity stars (~1000 km/s) allows the existence of stars with relativistic velocities attaining (1/3?2/3)c, where c is the speed of light. The increase of the kinetic energy of these stars by more than a factor of 100 is due to the replacement of one component of the binary with a supermassive black hole. This scenario takes candidate of relativisti©velocity stars outside our Galaxy, into intergalactic space, where they could be ejected from merging galaxies populated by supermassive black holes. At present, this is a hypothetical class of stars with anomalous kinematics, but it is already posing a serious challenge for modern astrometry, which, like 300 years ago, is still concerned with the detection of proper motions. While this was related to stars in the solar neighborhood at the time of Halley, is now a problem for studies of the most remote and weakest stars in intergalactic space. Possibilities for detecting such stars must be based on estimates of their abundances, that is, on their statistics. This paper is based on a presentation made at the conference “Modern Astrometry 2017,” dedicated to the memory of K.V. Kuimov (Sternberg Astronomical Institute, Moscow State University, October 23–25, 2017).

     

应力波对裂隙的作用

强大的应力波冲击加载,能使完整介质发生变形,形成新的裂隙,导致破坏。而介质中原有的裂隙,除能提高破碎效率,还能吸收应力波的能量,使得应力波在传播过程中衰减。因此,研究应力波与裂隙的相互作用,对于研究岩石爆破机理、应力波传播规律以及波的反演--材料的动态特性等有着十分重要的意义。本文着重论述了应力波与裂隙的相互作用和裂隙对应力波传播的衰减影响,也综述了当前国内外对此所进行的模型计算和实验技术。     

DCS－偶氮胂光度法测定钛酸锶烧结物中游离的氧化锶

ＤＣＳ－偶氮胂光度法测定钛酸锶烧结物中游离的氧化锶胡浩，周宏实江苏海安磷肥厂２２６６００ＤＣＳ－偶氮肿［２－（２－胂酸基苯偶氮）－７－（２，６－二氯－４－磺酸基苯偶氮）－１，８－二羟基－３，６－二磺酸萘］属双偶氮变色酸类显色剂，主要用于稀土元素的高灵...