Experiments on the Resistance of a Large Transport Vessel Navigating in the Arctic Region in Pack Ice Conditions

In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the Arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail.

Car-following Model and Its Stability under Ice and Snowfall Conditions

In order to describe the behavior of the car under ice and snowfall conditions more realistically,a vehicle following model based on the full velocity difference model is proposed under the premise of considering the speed difference and various kinds of ice and snowfall conditions. Under various road conditions,it obtains the critical stability curve of the model,and verifies that the worse the road condition is,the less stable the traffic flow is. In addition,the method of nonlinear analysis is used to obtain the solution of the kink density wave in the space headway under the unstable region. Finally,the conclusions are verified by numerical simulation,that worse road conditions,which means the road surface friction coefficient is small,will lead to greater instability region and worse anti-interference ability of traffic flow,and even cause more congestion and accidents. The conclusions make great contributions to handling the traffic jams and security issues under ice and snowfall conditions.

Some Recent Advances on Ice Related Problems in Offshore Engineering

This paper deals with several hot topics in ice related problems. In recent years, advances have been made on ice breaking modes, dynamic ice loads on offshore structures, ice-induced structural vibrations, Fatigue and fracture by ice-structure interaction, and design of jackets in the Bohai Gulf.

Biomass,nutrient uptake and fatty acid composition of Chlamydomonas sp.ICE-L in response to different nitrogen sources

Nitrogen removal from media by microalgae provides the potential benefit of producing lipids for biodiesel and biomass. However, research is limited on algal growth and biomass under different nitrogen sources and provides little insight in terms of biofuel production. We studied the influences of nitrogen sources on cell growth and lipid accumulation of Chlamydomonas sp. ICE-L, one of a promising oil rich micro algal species. Chlamydomonas sp.ICE-L grown in NH_4 Cl medium had maximum growth rate. While the highest dry biomass of 0.28 g/L was obtained in media containing NH_4NO_3, the highest lipid content of 0.21 g/g was achieved under nitrogendeficiency condition with a dry biomass of 0.24 g/L. In terms of total polyunsaturated fatty acids（PUFAs）production, NH_4NO_3 and NH_4 Cl media performed better than nitrogen-deficiency and KNO_3 media.Furthermore, NH_4NO_3 and NH_4 Cl media elucidated better results on C18：3 and C20：5 productions while KNO_3and-N conditions were better in C16：0, C18：1 and C18：2, comparatively.

内河破冰船实船振动试验研究

A series of tests of a full-scale river icebreaker was conducted to investigate the characteristics of ice-induced hull vibration.The test was conducted when the river icebreaker was operating in an ice-covered river at temperatures of-4 to 0°C with ice thicknesses of 300 to 400 mm.In the tests,the ice condition and icebreaker speed were chosen as the main influence factors.By analyzing the measured test data,we identified some important points regarding ice-induced hull vibration.When the river icebreaker navigates in an area with complete ice coverage,the peak value of the acceleration amplitude spectrum is highest.Also,the vibration response excited by the icebreaking load in an area with complete ice coverage exhibits more frequencies.With an increase in icebreaker speed,the vibration acceleration response gradually increases.However,habitability of the bow region on the main and driving decks is maintained due to the harmless vibration levels.In addition,the icebreaking operation of the river icebreaker causes violent local vibration of the grillage on the main deck.