Assimilation of buoy and satellite data in wave forecasts with integral control variables

The quality of numerical wave forecasts can be improved significantly by assimilating wave observations prior to the forecast. In the present study a technique for such assimilation is developed that exploits (a) the efficiency of a limited number of integral control variables, and (b) the effectiveness of variational (model-consistent) assimilation. The formal procedure is independent of the type of control variables and of the wave model (moreover, no adjoint wave model is required). In the present study, integral control variables are chosen to represent large-scale errors in the driving wind fields and uncertainties in the wave model. The assimilation technique is validated with observations of the ERS-1 satellite altimeter and two waverider buoys in two consecutive storms in the Norwegian Sea. The assimilation of the observations reduced the errors in the forecasted significant wave height at the buoy locations typically from 25% to 12%. For low-frequency waves the effect of the assimilation is similarly significant at one buoy location but marginal at the other buoy location.     

New species of the genus Xanthocalanus (Copepoda, Calanoida, Phaennidae) from the Laptev Sea

Sampling of the near-bottom calanoid copepods was performed on board of the research vessel Polarstern in 1993 in the Laptev Sea (Siberian Arctic). Three new species of Xanthocalanus were identified as such, and are described and figured here: X. spinodenticulatus sp. nov., X. laptevorum sp. nov. and X. polarsternae sp. nov.     

不断探索新办法适应机动车维修行业发展需要

汽车业的快速发展给汽车维修行业带来了机遇和挑战，过去的管理理念和方法已落后于形势，交通行业管理部门应积极探索新办法．适应形势发展的需要。     

Effect of traffic information on commuters' propensity to change route and departure time

Considerable public and private resources are devoted to the collection and dissemination of real-time traffic information in the Chicago area. Such information is intended to help individuals make more informed travel decisions, yet its effect on behavior remains largely unexplored. This study evaluates the effect of traffic information on travelers' route and departure time changes and provides a stronger basis for developing advanced information systems. Downtown Chicago automobile commuters were surveyed during the AM peak period. The results indicate that a majority of the respondents access, use and respond to information. For example, individuals use travel information to reduce their anxiety—even if they do not change travel decisions; this indicates that information may have “intrinsic” value. That is, simply knowing traffic conditions is valued by travelers. More than 60% of the respondents had used traffic information to modify their travel decisions. Multivariate analysis using the ordered probit model showed that individuals were more likely to use traffic reports for their route changes if they perceived traffic reports to be accurate and timely, and frequently listened to traffic reports. Respondents were more likely to change their departure times if they perceived traffic reports to be accurate and relevant, and frequently listened to traffic reports. The implication for Advanced Traveler Information Systems are that they may be designed to support both enroute and pre-trip decisions. ATIS performance, measured in terms of accuracy, relevance and timeliness would be critical in the success of such systems. Further, near-term prediction of traffic conditions on congested and unreliable routes (where conditions change rapidly) and incident durations is desirable.     

DIETARY MAGNESIUM DEFICIENCY INCREASES LEVELS AND FUNCTION OF Giα IN THE RAT HEART AFTER MYOCARDIAL INFARCTION

ＤＩＥＴＡＲＹＭＡＧＮＥＳＩＵＭＤＥＦＩＣＩＥＮＣＹＩＮＣＲＥＡＳＥＳＬＥＶＥＬＳＡＮＤＦＵＮＣＴＩＯＮＯＦＧｉαＩＮＴＨＥＲＡＴＨＥＡＲＴＡＦＴＥＲＭＹＯＣＡＲＤＩＡＬＩＮＦＡＲＣＴＩＯＮＳｈｉＢｉｎｇ；Ｊ．Ｅ．Ｈｅａｖｎｅｒ，Ｌ．Ｍ．Ｂｏｙｌａｎ...     

RECENT RESEARCH AND DEVELOPMENT OF POLYMER OPTICAL FIBRES

ＲＥＣＥＮＴＲＥＳＥＡＲＣＨＡＮＤＤＥＶＥＬＯＰＭＥＮＴＯＦＰＯＬＹＭＥＲＯＰＴＩＣＡＬＦＩＢＲＥＳ＊ＧＤＰｅｎｇ（彭刚定）ＰＬＣｈｕ（朱柏濂）（ＳｃｈｏｏｌｏｆＥｌｅｃｔｒｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，Ｕｎｉｖ．ｏｆＮｅｗＳｏｕｔｈＷａｌｅｓ，Ｋ...     

Impact of freshwater on a subarctic coastal ecosystem under seasonal sea ice (southeastern Hudson Bay, Canada). III. Feeding success of marine fish larvae

We monitored the feeding success (percent feeding incidence at length and mean feeding ratio at length) of Arctic cod (Boreogadus saida) and sand lance (Ammodytes sp.) larvae in relation to prey density, light, temperature and potential predator density under the ice cover of southeastern Hudson Bay in the spring of 1988, 1989 and 1990. Both prey density and light limited larval fish feeding. The relationship between feeding success and actual food availability (nauplii density X irradiance) was adequately described by an Ivlev function which explained 64 and 76% of the variance in Arctic cod and sand lance feeding success respectively. By affecting both prey density and irradiance, the thickness of the Great Whale River plume (as defined by the depth of the 25 isohaline) was the main determinant of prey availability. Arctic cod and sand lance larvae stopped feeding when the depth of the 25 isohaline exceeded 9 m. Limitation of feeding success attributable to freshwater inputs occurred exclusively in 1988, the only time when the depth of the 25 isohaline exceeded the 9 m threshold. The close dependence of larval fish feeding success on the timing of the freshet and plume dynamics suggests a direct link between climate and survival of Arctic cod and sand lance larvae. The actual impact of climate fluctuations and/or hydro-electric developments on recruitment will depend on the fraction of the larval dispersal area of the two species that is affected by river plumes.     

自换向辅助电路零电压转换PWM变流器(二)

介绍了一类新型的零电压转换(ZVT)的直-直PWM变流器,它使用了一个与辅助开关相连接的LC谐振电路,该电路被视为一个自换向辅助电路.它在较宽的负载范围为辅助开关实现零电流换向提供了一种简单可靠的方法,而不需任何电压源.此外,这种辅助电路与主电源变流器并联,保持了零电压转换特性.还分析了这种具有自换向辅助电路的零电压转换升压PWM方案,它的可行性与可靠性由实验数据证实,实验模型的额定功率为1kW,频率为100kHz.