气固同轴撞击流干燥试验研究

撞击流干燥（Impinging Stream Drying，ISD）技术是强化相间传热传质和加快颗粒干燥过程的有效方法。通过在自行设计的同轴水平撞击流试验装置上对物料进行的一系列干燥试验，验证了空气温度、颗粒喂料速率、颗粒预热温度等操作参数和撞击距离、撞击室容积等结构参数对干燥性能的影响，获得了同轴撞击流干燥的一般规律...     

Beiträge zur Isotopengeochemie von Erdgasen

It is the proper aim of geochemical investigations regarding natural gas to describe the processes of generation, migration and accumulation of gaseous compounds. By this way our research results should contribute to knowledge about the gas generating potential of organic matter and about the expected gas volumes in natural gas deposits.

The main topics in the authors' research project are

- isotopic characterization of hydrocarbon forming organic matter

- simulation of the generation of natural gas components by coalification processes (model experiments including also radiolytic gas formation from organic matter)

- investigation of various separation processes (diffusion, adsorption, solubility, mixing of gases. oxidation of natural gas components) affecting chemical compositions and isotopic signatures

- elucidation of pressure and temperature dependence of separation processes and especially of the elementary isotope separation cofficients in systems gas/sorbent

- as the main result, an interpretation concept for natural gas samples is proposed which is based on chemical and isotopic compositions of methane and ethane in the samples and which takes into consideration also separation processes.

Following this summarizing publication some of the most important results of our research work will be presented in more detail in three separate parts.     

The combination of aggregation,ARQ, QoS guarantee and mapping of Application flows in Very High Throughput 802.11ac networks

We investigate the performance of the IEEE 802.11ac MAC layer Aggregation schemes in light of QoS guarantee with the use of an ARQ protocol, and in very high PHY rates. The investigation is done in different models of mapping Application flows into Traffic Streams and Access Categories. We show that when the IEEE 802.11ac ARQ protocol is used with relatively high bit error rates, it is not effective to use the full aggregation capability. Second, we show that there is not one best model of mapping Application flows into Traffic Streams and Access Categories. In particular, using two Access Categories is sometimes less efficient than using one.     

生物活动对海床沉积物工程地质特征改造研究

底栖穴居动物是河口潮滩生态系统的重要组成部分,它对沉积物的二次改造作用非常重要。本文以黄河三角洲钓 口区潮滩为研究对象,研究了不同生物密度对沉积物工程地质特征的改造,包括滩面形态、沉积物强度、以及沉积物颗粒大小 的改变。在此基础上探讨了生物活动与滩面凹坑,沉积物强度非均匀性以及研究区浮泥之间的关系。     

Stokes Flow in a Slowly Varying Two-Dimensional Periodic Pore

This article presents a series solution to the velocity in a two-dimensional long sinusoidal channel. The approach is based on a stream function formulation of the Stokes problem and a series expansion in terms of the width to the length ratio, which is considered small. Results show how immobile zones may appear and even flow separation and nonturbulent eddies, even in the absence of prima facie dead-end pores. It is shown that the flow tends to concentrate in strips connecting pore throats.     

Estimation of carbonate concentration and characterization of marine sediments by Fourier Transform Infrared Spectroscopy

Fourier Transform Infrared Spectroscopy (FTIR) is a well established method for the characterization of mineralogical and geochemical properties of marine sediments. Understanding the biogeochemical changes in marine ecosystems is challenging task since it requires adequate analytical techniques and efforts. Biogeochemical characteristics of twenty one marine sediment samples collected off Chennai coast, Bay of Bengal, India were analyzed using FTIR spectroscopy. The FTIR peaks at 1460 cm⁻¹ (stretching vibration) and 880 cm⁻¹ (bending vibration) were used for carbonate determination. To verify the FTIR results, the obtained carbonate data were compared with carbonate values obtained by chemical analyses. The ranges of carbonate in sediments using FTIR and chemical analyses were 4.5–9.6% and 4.8–10%, respectively. The significant positive relationship was obtained between the carbonate results of FTIR and chemical analyses. This study demonstrates that instead of expensive and time consuming chemical methods, FTIR spectroscopic technique is found as a suitable, rapid and effective method for the quantification of carbonate in marine sediments.     

Stagnation point flow and heat transfer over a non-linearly moving flat plate in a parallel free stream with slip

An analysis is presented for the steady boundary layer flow and heat transfer of a viscous and incompressible fluid in the stagnation point towards a non-linearly moving flat plate in a parallel free stream with a partial slip velocity. The governing partial differential equations are converted into nonlinear ordinary differential equations by a similarity transformation, which are then solved numerically using the function bvp4c from Matlab for different values of the governing parameters. Dual (upper and lower branch) solutions are found to exist for certain parameters. Particular attention is given to deriving numerical results for the critical/turning points which determine the range of existence of the dual solutions. A stability analysis has been also performed to show that the upper branch solutions are stable and physically realizable, while the lower branch solutions are not stable and, therefore, not physically possible.     

Levels of polycyclic aromatic hydrocarbons,polychlorinated byphenyls,methylmercury and butyltins in the natural UNESCO reserve of the biosphere of Urdaibai (Bay of Biscay,Spain)

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), methylmercury (MeHg⁺) and butyltins (mono-, di- and tri-butyltin, MBT, DBT and TBT) were monitored in oysters (Crassostrea sp.) and sediments collected in different sampling points of the UNESCO reserve of the biosphere of Urdaibai (Bay of Biscay) from March 2006 to June 2007. In the case of oyster samples, concentrations in the 290–1814 µg kg^?1 (PAHs), 70–475 µg kg^?1 (PCBs), 75–644 µg kg^?1 (MeHg⁺) and 200–1300 µg kg^?1 (as a sum of the three butyltins) ranges were obtained. In most samples TBT was the most abundant butyltin, followed by DBT and MBT. It should be highlighted that most samples exceeded the highest range (367 µg kg^?1) found in the last mussel watch programme carried out by the National Oceanic and Atmospheric Administration (NOAA) for butyltins in oyster samples. This could be due to the presence of a shipyard in the estuary. Sediment concentrations ranged as follows: total PAHs (856–3495 µg kg^?1) and total PCBs (58–220 µg kg^?1). Organometallic species were always below the limits of detection (LODs) (0.24 µg kg^?1 for MeHg⁺, 0.6 µg kg^?1 for MBT, 0.48 µg kg^?1 for DBT and 1.1 µg kg^?1 for TBT). In both sediment and oyster PAH sources were mostly combustion. In the case of PCBs, 4-6 chlorine-atom congeners were the most abundant ones. Slight differences in the profile of PAHs as well as PCBs can be detected when the matrices were compared with each other. Finally, in the case of PAHs, sediment and water column played the main role in the accumulation pathway into the organisms in all the sampling stations.     

Determination of Trace Metals in Antarctic Sediments from Terra Nova Bay - Ross Sea

Abstract

Trace metals (Cu, Pb, Zn, Cd, Cr, Ni, Co, Mn) and iron concentration were determined in several sediments collected in the Antarctica (Terra Nova Bay—Ross Sea). Samples were analyzed by inductively coupled plasma (ICP-AES) after selective and total extraction. The results are in good agreement with the data previously collected in the same area.     

Analytical methods and problems related to the determination of organotin compounds in marine sediments

The determination of organotin compounds in bottom sediments is a complex process that requires a number of analytical steps, i.e. sample collection, transport and storage; extraction of analytes from sediment; derivatization; extract purification; enrichment; and the final chromatographic measurement. The whole process is time and labour consuming, and subject to securing sample representativeness. In this review the most frequently encountered problems and the examples of possible analytical solutions are presented, which encompass the specific steps of speciation analysis of these toxic compounds.