Calibration of a Par-Tec 200 laser back-scatter probe FOR in situ sizing of fluvial suspended sediment

The in situ or effective particle size distribution of fluvial suspended sediment may differ considerably from that of the chemically dispersed mineral fraction owing to flocculation. Obtaining a meaningful measure of the effective particle size distribution ideally requires that measurements should be made in situ. A rigorous assessment of the associated degree of flocculation also requires that the same measurement technique is used subsequently to establish the absolute particle size composition of the suspended sediment by analysis of the chemically dispersed mineral fraction. While few in situ measurement devices currently exist, a Par-Tec 200 laser back-scatter probe has previously been shown to be capable of making both in situ and laboratory particle size measurements of fluvial sediment. The accuracy and precision of this device is assessed in this paper. While able to distinguish relative size differences with a high degree of precision, the Par-Tec 200 performed poorly in terms of accuracy when compared with measurements made using a laser diffraction device. A calibration algorithm has been devised for the Par-Tec 200 size data, using standard sediment samples sized by means of a laser diffraction device as the reference. Application of the calibration to Par-Tec 200 measurements of heterogeneous sediment samples significantly improved the representativeness of the particle size distribution, both in terms of overall form, and the median particle size. © 1998 John Wiley & Sons, Ltd.     

Tracing tsunami signatures of the ad 551 and ad 1303 tsunamis at the Gulf of Kyparissia (Peloponnese,Greece) using direct push in situ sensing techniques combined with geophysical studies

The western Peloponnese was repeatedly hit by major tsunami impacts during historical times as reported by historical accounts and recorded in earthquake and tsunami catalogues. Geological signatures of past tsunami impacts have also been found in many coastal geological archives. During the past years, abundant geomorphological and sedimentary evidence of repeated Holocene tsunami landfall was found between Cape Katakolo and the city of Kyparissia. Moreover, neotectonic studies revealed strong crust uplift along regional faults with amounts of uplift between 13 m and 30 m since the mid-Holocene. This study focuses on the potential of direct push in situ sensing techniques to detect tsunami sediments along the Gulf of Kyparissia. Direct push measurements were conducted on the landward shores of the Kaiafa Lagoon and the former Mouria Lagoon from which sedimentary and microfaunal evidence for tsunami landfall are already known. Direct push methods helped to decipher in situ high-resolution stratigraphic records of allochthonous sand sheets that are used to document different kinds of sedimentological and geomorphological characteristics of high-energy inundation, such as abrupt increases in grain size, integration of muddy rip-up clasts and fining upward sequences which are representative of different tsunami inundation pulses. These investigations were completed by sediment coring as a base for local calibration of geophysical direct push parameters. Surface-based electrical resistivity tomography and seismic data with highly resolved vertical direct push datasets and sediment core data were all coupled in order to improve the quality of the geophysical models. Details of this methodological approach, new in palaeotsunami research, are presented and discussed, especially with respect to the question of how the obtained results may help to facilitate tracing tsunami signatures in the sedimentary record and deciphering geomorphological characteristics of past tsunami inundation. Using direct push techniques and based on sedimentary data, sedimentary signatures of two young tsunami impacts that hit the Kaiafa Lagoon were detected. Radiocarbon age control allowed the identification of these tsunami layers as candidates for the ad 551 and ad 1303 earthquake and tsunami events. For these events, there is reliable historical data on major damage on infrastructure in western Greece and on the Peloponnese. At the former Mouria Lagoon, corroborating tsunami traces were found; however, in this case it is difficult to decide whether these signatures were caused by the ad 551 or the ad 1303 event.     

STUDIES ON CULTURE CONDITIONS OF BENTHIC DIATOMS FOR FEEDING ABALONE I.EFFECTS OF TEMPERATURE AND LIGHT INTENSITY ON GROWTH RATE

INTRODUCTIONBenthicdiatomscomPrisethemaininitialfoodforjuvenileabalone.ItisimPortanttocIJlturehighqualitybenthicdiatornsduringtheeariystageofjuvenileabaloneculture.AtpresentthespeCesofbenthicdiatomsusedinabalonebedingfannsprirnarilycomefromnaturalpopulations.SomespedesinseveralgenerasuchasNavicula,Ntzchia,Caroneis,Achnanthes,AmPhoraareusuallythedothenantspch(Chen,etal.,l977,Ukiandaxuchi,l979,Nonnan-Boudnauetal.,l986,Austinetal.l990).Inordertoselodsornespedeswithhighadaptability,fas…     

高层建筑刚性桩复合地基反力现场测试研究

基于对高层建筑下带垫层刚性桩复合地基桩及桩间土压力的原位测试结果,分析了复合地基的桩顶及桩间土表面压力分布特征、桩与桩间土荷载分担特性及基础的荷载-沉降特性。实测结果表明,垫层的设置可较好地发挥桩间土的承载力,实现桩土共同承担上部结构荷载。将所得结果与载荷试验得到的结果进行对比,所得结论可供理论研究和工程设计参考。     

Design of Hybrid Steam-In Situ Combustion Bitumen Recovery Processes

Given enormous capital costs, operating expenses, flue gas emissions, water treatment and handling costs of thermal in situ bitumen recovery processes, improving the overall efficiency by lowering energy requirements, environmental impact, and costs of these production techniques is a priority. Steam-assisted gravity drainage (SAGD) is the most widely used in situ recovery technique in Athabasca reservoirs. Steam generation is done on surface and consequently, because of heat losses, the energy efficiency of SAGD can never be ideal with respect to the energy delivered to the sandface. An alternative to surface steam generation is in situ combustion (ISC) where heat is generated within the formation through injection of oxygen at a sufficiently high pressure to initiate combustion of bitumen. In this manner, the heat from the combustion reactions can be used directly to mobilize the bitumen. As an alternative, the heat can be used to generate steam within the formation which then is the agent to move heat in the reservoir. In this research, alternative hybrid techniques with simultaneous and sequential steam-oxygen injection processes are examined to maximize the thermal efficiency of the recovery process. These hybrid processes have the advantage that during ISC, steam is generated within the reservoir from injected and formation water and as a product of oxidation. This implies that ex situ steam generation requirements are reduced and if there is in situ storage of combustion gases, that overall gas emissions are reduced. In this research, detailed reservoir simulations are done to examine the dynamics of hybrid processes to enable design of these processes. The results reveal that hybrid processes can lower emitted carbon dioxide-to-oil ratio by about 46%, decrease the consumed natural gas-to-oil ratio by about 73%, reduce the cumulative energy-to-oil ratio by between 40% and 70% compared to conventional SAGD, and drop water consumption per unit oil produced. However, oil recovery is between 25% and 40% below that of SAGD. Design of successful hybrid steam–oxygen processes must take into account the balance between injected steam and amount of injected oxygen and combustion gas products that dilute injected and in situ-generated steam in the depletion chamber by lowering its partial pressure, and thus its saturation temperature which in turn impacts production rates and recovery.     

福建省GPS连续观测基准站的选址

介绍了福建省30个GPS连续观测基准站的勘选过程。在勘选过程中,应用TEQC数据预处理软件,对预选的基准站进行24小时的测试,并做出质量分析。从而勘选出满足规范、可靠、安全、科学的GPS连续观测基准站站址,为GPS连续观测基准站建站提供依据。     

Multivariate homogeneity testing in a northern case study in the province of Quebec,Canada

In regional frequency analysis, the examination of the regional homogeneity represents an important step of the procedure. Flood events possess multivariate characteristics which can not be handled by classical univariate regional procedures. For instance, classical procedures do not allow to assess regional homogeneity while taking into consideration flood peak, volume and duration. Chebana and Ouarda proposed multivariate discordancy and homogeneity tests. They carried out a simulation study to evaluate the performance of these tests. In the present paper, practical aspects are investigated jointly on flood peak and flood volume of a data set from the Côte‐Nord region in the province of Quebec, Canada. It is shown that, after removing the discordant sites, the remaining ones constitute a homogeneous region for the volumes and heterogeneous region for the peaks. However, if both variables are jointly considered, the obtained region is possibly homogeneous. Furthermore, the results demonstrate the usefulness of the bivariate test to take into account the dependence structure between the variables representing the event, and to take advantage of more information from the hydrograph. Copyright © 2009 John Wiley & Sons, Ltd.     

工程岩体裂隙渗透性试验方法研究及应用

现代水电、交通、矿山、能源及核废料处理等地下工程中,洞室岩体原地承载能力以及在工程运行状态下洞室围岩的实际透水性状等岩体力学参数,是地质勘测不可缺少的基础资料,也是科学地优化工程设计的依据。由于传统的裂隙渗透性测试技术与方法如常规压水试验已不能满足工程建设发展的需要,达不到有些复杂工程对岩体渗透性的特殊设计要求,因此,有必要进行多种形式的工程岩体裂隙渗透特性分析和研究,从而针对特定工程,选择合适的试验方法,探明其确切渗透规律,以保证工程设计的准确性和有效性。     

Testing Hypotheses for the Mount Isa Copper Mineralisation with Numerical Simulations

We have applied reactive transport simulations to evaluate conceptual models of hydrothermal fluid flow related to the Mesoproterozoic Mount Isa copper mineralisation. Numerical experiments have been performed specifically to investigate whether fluid flow was driven by mechanical deformation, higher than hydrostatic fluid pressure gradients, or thermal buoyancy, and what the mechanism of ore deposition was. One distinct feature of the Mount Isa mineralising system is a region of massive silica-rich alteration that surrounds the copper ore bodies within the Urquhart shale, indicating upward flow of a cooling fluid. Hydromechanical modelling revealed that contraction and horizontal shear can produce a dilation pattern that favours upward fluid flow, whereas strike slip movement causes dilation of pre-existing vertical structures. Reactive transport models show that hydraulic head driven flow is more likely to produce a more realistic silica alteration pattern than free thermal convection, but neither process generates a flow pattern capable of precipitating copper at the appropriate location. Instead we propose that gravity driven flow of a dense oxidised basin brine led to chalcopyrite mineralisation by fluid-rock reaction.     

Dynamic response of a flexible pavement submitted by impulsive loading

The present paper introduces results from measurements on site using a falling weight deflectometer (FWD). This apparatus is used for non-destructive testing of damaged pavement in order to estimate the elastic modulus of each layer. The basin of deflection induced by a controlled load can be determined with precision and can reflect the behavior of the pavement structure. The interpretation of data generated by FWD leans on inverse analysis processes. Data from FWD combined with the thickness of layers inform on the evolution of the Young's modulus of each layer of the structure along the studied road profile. This information can be also used to estimate its lifespan and possible repairs to be carried out.