Effects of fundamental structure parameters on dynamic responses of submerged floating tunnel under hydrodynamic loads

This paper investigates the effects of structure parameters on dynamic responses of submerged floating tunnel (SFT) under hydrodynamic loads. The structure parameters includes buoyancy-weight ratio (BWR), stiffness coefficients of the cable systems, tunnel net buoyancy and tunnel length. First, the importance of structural damp in relation to the dynamic responses of SFT is demonstrated and the mechanism of structural damp effect is discussed. Thereafter, the fundamental structure parameters are investigated through the analysis of SFT dynamic responses under hydrodynamic loads. The results indicate that the BWR of SFT is a key structure parameter. When BWR is 1.2, there is a remarkable trend change in the vertical dynamic response of SFT under hydrodynamic loads. The results also indicate that the ratio of the tunnel net buoyancy to the cable stiffness coefficient is not a characteristic factor affecting the dynamic responses of SFT under hydrodynamic loads.

A thin liquid film and its effects in an atomic force microscopy measurement

Recently, it has been observed that a liquid film spreading on a sample surface will significantly distort atomic force microscopy (AFM) measurements. In order to elaborate on the effect, we establish an equation governing the deformation of liquid film under its interaction with the AFM tip and substrate. A key issue is the critical liquid bump height y(0c) at which the liquid film jumps to contact the AFM tip. It is found that there are three distinct regimes in the variation of y(0c) with film thickness H, depending on Hamaker constants of tip, sample and liquid. Noticeably, there is a characteristic thickness H* physically defining what a thin film is; namely, once the film thickness H is the same order as H* , the effect of film thickness should be taken into account. The value of H* is dependent on Hamaker constants and liquid surface tension as well as tip radius.

Investment prospects in the production of the common carp (Cyprinus carpio) fingerlings in freshwater ponds

Since the introduction of Common carp Cyprinus carpio in Oyo State (Nigeria) from Israel in 1964, various local breeding methods have been employed in carp rearing to improve the survival rate at all stages of development during breeding. The physico-chemical parameters of the ponds which were simultaneously investigated for carp rearing in this study includes temperature (t), dissolved oxygen (DO) and hydrogen-ion concentration (pH). However, high rates of water displacement in the breeding ponds were unfavourable to the development of zooplankton which play important role in the food web of C. carpio. The survival rates of 15.88-69.50% and 19.60-33.83% obtained for the egg-hatchling and hatchling-fingerling stages respectively were encouraging. A breeding performance of this magnitude was found to be viable, breaking even in the fourth year. However, an increase in size of this trial project would be more profitable and increase fingerling supply as well as provide employment opportunities. This study thereby provides some baseline information on some local techniques and progress in the propagation of C. carpio and scope for further improvement

Parametric Analysis for Monitoring 2D Kinetics of Receptor-Ligand binding

Thermal fluctuation approach is widely used to monitor association kinetics of surface-bound receptor-ligand interactions. Various protocols such as sliding standard deviation (SD) analysis (SSA) and Page's test analysis (PTA) have been used to estimate two-dimensional (2D) kinetic rates from the time course of displacement of molecular carrier. In the current work, we compared the estimations from both SSA and modified PTA using measured data from an optical trap assay and simulated data from a random number generator. Our results indicated that both SSA and PTA were reliable in estimating 2D kinetic rates. Parametric analysis also demonstrated that such the estimations were sensitive to parameters such as sampling rate, sliding window size, and threshold. These results furthered the understandings in quantifying the biophysics of receptor-ligand interactions.

Plankton periodicity and some physicochemical parameters of the intake channel of Lake Chad

This study examines zooplankton periodicity and some physicochemical parameters of the intake channel of Lake Chad (Nigeria). Nine different zooplankton species were identified at the sampling station 1, while seven different zooplankton species were identified at the sampling station 2 (the intake channel of Lake Chad). Each identified zooplankton species was grouped according to its major group of copepods, Cladocera or Rotifera. The copepods dominated the zooplankton community with the highest numbers of occurrence as Cyclopedia species throughout the course of the study at both station l and 2. There was a clear evidence of the influence of organic manure nutrients on total zooplankton population at station 1 when compared to that of station 2. The water quality variables measured in the course of this study show that the surface water temperature in station 1 ranges from 27.5 degree C to 30.5 degree C. The pH ranges from 6.8 to 8.5, while D.O. contents ranges from 2.9mg/L to 6.1mg/L and alkalinity recorded was 172.00 to 208.00. At the station 2 the water quality parameters obtained show that surface water temperature ranges from 27.3 degree C to 30.2 degree C, pH ranges between 6.9 to 8.5, while the D.O contents ranges from 3.0 mg/L to 6.2 mg/L.Alkalinity ranges from 172mg/L to 212 mg/L

Plume Parameters and Thruster Properties of a Low Power Arcjet

Abstract. A low power arcjet-thruster of 1 kW-class with gas mixture of H2-N2 or pure argon as the propellant is fired at a chamber pressure about 10 Pa. The nozzle temperature is detected with an infrared pyrometer; a plate set perpendicular to the plume axis and connected to a force sensor is used to measure the thrust; a probe with a tapered head is used for measuring the impact pressure in the plume flow; and a double-electrostatic probe system is applied to evaluate the electron temperature. Results indicate that the high nozzle temperature could adversely affect the conversion from enthalpy to kinetic energy. The plume flow deviates evidently from the LTE condition, and the rarefied-gas dynamic effect should be considered under the high temperature and low-pressure condition in analyzing the experimental phenomena.

Laser intensity effects in photoemission and photoelectron spectra produced in laser-induced autoionisation

Strong laser-field-induced autoionisation in the presence of both photoionising and radiative decay of the autoionising state (AS) is investigated, focusing on the laser intensity dependence of the photoemission and photoelectron spectra. In contrast to previous predictions, power broadening and increasing reduction of the doublet peak heights with field strength are found in the photoemission spectrum. Similar effects leading to considerable suppression and even complete disappearance of the lowest-order peaks in the photoelectron spectrum, together with peak switching, are also demonstrated, which are closely related to above-threshold ionisation. In addition, it is suggested that the total number of energetic photoelectrons may serve as an alternative to measuring the atomic parameters of the AS. All these effects are attributed to the presence of the strong `probe': laser-induced decay of the AS.

The assessment of physico-chemical parameters of Shiroro Lake and its major tributaries

The physico-chemical parameters of the surface water of Shiroro Lake and its major tributaries at their entry point to the reservoir were assessed over a period of eighteen months. As in other African inland water bodies there were seasonal variations in the parameters measured. The hydrological regime of the lake, precipitation chemistry, bedrock chemistry and hydro-electric power generation influence and determine the inputs of dissolved organic carbon, nutrient levels and water quality of the lake. The added nutrients to the lake by means of the major tributary rivers and inundation of surrounding areas also influence the water quality of the lake. The wet season mean values for water and air temperature were significantly (P <0.05) higher than dry season mean values in all stations. However, for pH, Dissolved oxygen and Phosphate-phosphorus the dry season mean values were higher than wet season mean values

Coastal brownfields and adaptation to climate change: Discussions on potential hazards from contaminated groundwater displacement due to saltwater incursion

Toxic-waste associated with coastal brownfield sites can pose serious risks to human and environmental health. In light of anticipated sea-level rise (SLR) due to global climate change, coastal brownfields require heightened attention. The primary intent of this study is to pose questions and encourage discussion of this problem among policy makers. Impacts from SLR on coastal zones are examined within a brownfield policy framework and, current coastal brownfield policy discussions with respect to SLR are also examined. (PDF contains 4 pages)

Influence of atomic densities on propagation property for ultrashort pulses in a two-level medium

The influence of atomic densities on the propagation property for ultrashort pulses in a two-level atom (TLA) medium is investigated. With higher atomic densities, the self-induced transparency (SIT) cannot be recovered even for 2π ultrashort pulses. New features such as pulse splitting, red-shift and blue-shift of the corresponding spectra arise, and the component of central frequency gradually disappears.