西铁城精机开发出大口径重切CNC自动车床

西铁城精机（CitiZen Machinery，长野县·御代田町）将于2008年4月25日上市小犁CNC自动车床“Cincom”系列的新产品“A32-VII”。该机犁在改进主轴丁作台移动型CNC白动车床“A20”系列的机械构造、提高刚性的同时，将最大加工直径加大到了32mm。机型有标准型和无导套型，分别备有右及岸丰轴机。标准价格均为974万4000日元（含税）。     

低速机连杆大端轴瓦安装挤压点分析

某新型低速柴油机连杆在样件加工完成后,先对连杆大端轴承孔进行尺寸测量,然后通过轴瓦挤压点实验,得到连杆大端挤压点值。采用有限元方法计算轴瓦挤压点,仿真计算结果与实验结果相符,仿真方法对实验进行了很好的验证和补充作用。通过在仿真模型中改变连杆大端连接螺栓位置,分析了连接螺栓位置对轴瓦挤压点影响规律。     

铺缆船用电缆埋设犁整机拖曳力学分析

铺缆船用电缆埋设犁是用于海底电缆铺设的专用装备.在铺缆船拖绳提供的拖曳力作用下,电缆埋设犁在海底实现边挖沟边铺设电缆.电缆埋设犁在工作过程中,受力情况非常复杂.为了保持电缆埋设犁行进过程中能有效挖掘海底土壤和稳定性,需要对埋设犁工作过程中的整机受力情况及铺缆船的拖绳受力情况进行综合分析与研究.该文以某型深水埋设犁挖掘工况为实例,从埋设犁整机受力情况入手,对埋设犁整机受力和铺缆船拖曳力相互关系及影响进行分析,为合理选用拖绳和确定参数,更好地保证电缆埋设犁顺利进行水下挖沟铺缆作业提供理论依据.     

五轴联动数控铣床高效加工螺旋浆曲面

把微分几何中曲线与曲面之间的“切触”概念应用于复杂曲面的数控加工,提出用圆柱铣刀和圆锥盘铣刀的外圆在五坐标联动中加工三维自由曲面的最佳切触条件.文章的特色是利用曲线与曲面之间可以比曲面与曲面之间贴合得更紧密的特点,把微分几何里的曲线与曲面之间的“切触”概念应用于曲面数控加工.     

小型独立承运商以星航运的生存法则

正2017年4月1日,OCEAN联盟和THE联盟开始运行。2M联盟与现代商船的三年期VSA协议山也已敲定。东西向主干航线上非联盟集运公司的生存空间做被极度挤压。以星在东西向主干航线市场上的生存空间被极度挤压非联盟集运公司在亚洲北欧(亚欧)、亚洲-地中海、亚洲-美东和亚洲-美西这四条航线区域的生存空间受到极大的挤压(表1)。     

铝镁合金半圆球工件挤压拉伸加工工艺研究

针对制作材料为5A06牌号的铝镁合金浮球,小批量生产工件,制作时分两半圆球压制拉伸,再组焊成球的工艺过程以及在以往挤压拉伸半圆球的生产过程中次品、废品高,造成施工成本较高的现象,通过理论计算和借鉴以往的加工经验,对半圆球挤压拉伸的膜具、工艺流程进行了改进。经多次试验取得了良好的效果,产品合格率达到98%以上。     

内螺纹挤压攻丝的底径计算及加工技术

本文探索一种较为精确地计算内螺纹挤压攻丝所需底孔尺寸的方法，并在介绍冷挤攻丝加工技术的同时，验证了计算的准确性。     

铺缆船用电缆埋设犁土壤挖掘阻力计算

传统的计算埋设犁土壤挖掘阻力的方法一般采用经验公式计算。经验公式依赖丰富的试验数据，且只能适应特定形状和尺寸的埋设犁。由于埋设犁的形状和尺寸各不相同，基于经验公式计算土壤挖掘阻力的方法准确性不高。根据土力学基本原理，在力学分析的基础上，运用数学方法进行公式推导，得到用于计算不同形状尺寸埋设犁挖掘阻力的理论方法，解决依赖经验公式计算土壤挖掘阻力的局限性。     

基于子结构有限元法的面板堆石坝挤压破坏机理分析

面板结构性破损问题已成为了影响高面板堆石坝安全建设及运行的核心问题。基于天生桥一级面板堆石坝发生的面板挤压破坏,建立了面板-垂直缝-堆石体子结构模型,通过施加法向水压力及轴向水平位移,分析面板混凝土及垂直缝部位的挤压应力和应变,揭示面板发生挤压破损的机理。结果表明:面板在坝轴线方向为分块结构,水压力作用引起的面板向下游方向的挠曲变形将导致垂直缝处呈现上游表面压紧、下游底部张开趋势,垂直缝面上压力表现为表面大、底部小的分布形态,形成面板垂直缝面上部应力集中,随着坝轴向位移的增加,向河床中部面板的挤压集中应力逐渐加剧,最终导致垂直缝处两侧混凝土的挤压破坏。     

国内外小模数齿轮刀具的现状和发展趋势

小模数齿轮刀具通常包括滚刀、铣刀、插齿刀和剃齿刀等复杂刀具。提高这类刀具的质量和性能是提高小模数齿轮加工精度和生产效率的关键因素之一。国内外加工小模数齿轮的方法主要是采用范成滚切工艺。为     

Exploring the effects of passenger rail franchising in Britain: Evidence from the first two rounds of franchising (1997-2008)

This paper provides an up-to-date review of the previous literature concerning the impact of passenger rail franchising on productivity and costs in Britain, and also presents important new evidence. In particular, the extension in time of previously-used datasets offers the first opportunity to study the impacts of re-franchising. The previous literature emphasised the failure of franchising to produce sustained productivity gains, with a sharp deterioration in productivity after 2000. The new evidence presented offers a somewhat more positive view of the British experience. It suggests that part of what was previously considered to be falling productivity may in fact be due to exogenous changes in diesel prices. Further, new data suggests that the recent increases in costs have resulted in higher quality of service. Finally, competitive re-franchising, and the associated unwinding of short-term management and re-negotiated contracts, seems to have led to improvements in productivity between 2006 and 2008. Nevertheless, it remains the case that passenger rail franchising in Britain has failed to reduce costs in the way experienced in many other industries and in rail in other European countries. The evidence is that somewhat larger franchises, avoiding overlapping and optimising train density and length, should reduce costs. We also speculate that the major increase in wages and conditions of staff might be moderated by longer franchises, although that remains to be proved. This re-appraisal of the British case is important in the context of the wider international interest in the use of franchising in passenger rail, and its relevance to the current review of ways of introducing competition into the domestic rail passenger market in Europe.     

关于加强日本海西部海事气象保障服务的建议

随着罗津港使用权的获取,自罗津港出入的中国船舶将不断增多,因此对日本海西部的气象保障服务需求势必不断增加。为加强日本海西部海事气象保障服务水平,使其能够为罗津港附近海域在海运、港口管理和海上作业等方面更好地起到规避风险、提高效益的作用,文中根据对目前日本海西部海事气象保障服务现状的调研结果,指出了当前日本海西部海事气象保障服务存在着区域划分不合理、精细化程度不足以及服务形式过于单一等问题。据此,结合目前国内外海事气象保障服务的思路,提出了针对于日本海西部的海事气象保障服务的建议,可为提升日本海西部海事气象保障服务的升级换代提供一些参考思路。     

双龙河口闸下港区淤积原因分析

根据断面水文测验结果，分析确定了海区底质泥沙特性，海水含沙量及流速；对闸下港区造成泥沙淤积的原因进行了较深人的分析；根据水文测验的有关数据，运用一般“文献方法”和“规范方法”分别对港区泥沙淤积强度作了估算；对于如何冲淤和减淤，从方法上和理论上作了论述。     

A study of the cabotage policy in Nigeria from the prisms of ship acquisition and shipbuilding

It is trite that shipping is pivotal to the economic development of Nigeria. Aside from significantly contributing to the country’s revenue, shipping is an indispensable aspect of the oil and gas sector, the bastion of Nigeria’s economic, sociopolitical, and infrastructural development. Thus, active participation of Nigerians in the shipping subsector, as well as other sectors, is unassailable and imperative, culminating in the introduction of cabotage in Nigeria. The kernel of this paper is to critically analyse the cabotage regime in Nigeria from the lenses of ship acquisition and shipbuilding with a view to enhancing indigenous participation in coastal and inland waterway transport in the country. The author argues that inadequate funding and absence of investment are central in hampering ship acquisition and the development of shipbuilding capability, thereby undermining cabotage in Nigeria. This paper further asserts that the extant cabotage legal regime in Nigeria is fundamentally flawed due to the existence of waivers without safeguards to protect indigenous ship operators. Moreover, the waiver regime does not encourage technology transfer. The paper concludes by reiterating that adequate funds and investments in human and shipping infrastructural development and the amendment of the Cabotage Act to reflect the removal of surcharges and the inclusion of transfer of technology and other safeguards to the waivers are imperative in ensuring a proper and effective cabotage regime in Nigeria.     

Intrusions of eastern North Atlantic central waters and phytoplankton in the north and northwestern Iberian shelf during spring

The influence of intrusions of eastern North Atlantic central water (ENACW) in the north and northwestern Iberian shelf on phytoplankton composition and abundance and on particle-size distributions of seston was analyzed using data collected on three extensive cruises during spring 1991 and 1992. Water with temperature and salinity values between 12.20 and 13.86 °C and between 35.66 and 35.98 psu, respectively, characteristics of the subtropical type of ENACW (ENACW_t), was detected in the upper 100 m of the water-column in all cruises, but particularly in the western coast in 1992. The highest salinity values of this water were found near the surface (0–100-m depth) and in early spring 1992, while minimum salinity values, and also minimum geographical extension, were found in late spring in both years. Phytoplankton blooms concentrated in frontal areas between different water types, with maximum intensity and extension in early spring.Using temperature and salinity characteristics, samples were classified in four groups corresponding to the major water types found in the region: Bay of Biscay central water (BBCW), two segments of ENACW of different salinity and surface water influenced by continental runoff. This classification was significantly confirmed by three independent discriminant analyses using hydrographic and chemical (dissolved nutrients and chlorophyll) variables, phytoplankton species abundance variables and particle-size concentration of seston variables. Phytoplankton blooms related to the presence of saline waters were characterized by the dominance of either chain-forming diatoms or a mixture of diatoms and phytoflagellates and high concentrations of seston. The diatom species dominating in saline waters were typical of upwelling-induced blooms occurring generally during summer. Blooms occurring in waters influenced by runoff also contained diatoms but in lower numbers than those of saline waters. Nutrients were not exhausted in the region, suggesting that phytoplankton populations were still in active growth. These results are interpreted taking into account the known variability in water-mass formation and in the poleward current driving ENACW_t along the shelf, and indicate that saline intrusions are a major feature affecting the distribution and composition of plankton in the spring in the southern Bay of Biscay, thus enlarging to a wider spatial scale their reported influence on the pelagic ecosystem.     

Union rivalry and crew reform in shipping: A United States—Australia comparison

The national-flag fleets of most of the traditional martitime nations have, in virtually every case, been in decline in the 1980s and 1990s, despite the continued growth of ocean shipping. They have declined in terms of numbers of vessels and numbers of sea-going jobs, although not necessarily in terms of cargo carried. However, a number of those nations have responded to the changed technological and competitive conditions with some success by attempting to adjust crewing and work practices on vessels at sea. Neither the USA nor Australia has been in the forefront of such change. However, considerably more progress has been made in modernizing crewing practices and work rules in the Australian-flag fleet than in the US-flag fleet. There are a variety of reasons for this, inluding government policy. However, it is our argument that one of the principal reasons the US fleet lags behind the Australian fleet in the adoption of modern crewing practices and work rules is the much greater degree of union rivalry in the US shipping industry. In fact, while the degree of fragmentation and rivalry among unions in the Australian flag fleet has declined dramatically since 1980, their US cousins have continued, and in some ways expanded, their pattern of fratricidal behavior. First we shall discuss some of the technological and competitive imperatives that are driving human resource management practices in shipping and the crewing and industrial relations adjustments that are being made around the world to adjust to them. Then we shall indicate how the Australian and US fleets have responded to these challenges. This will be followed by a discussion of unionism in the Australian and US maritime industrics as it has devloped in the last two decades of the twentieth century. Finally, we shall draw conclusions about the impact of different patterns of unionization.     

A generalized model of pelagic biogeochemistry for the global ocean ecosystem. Part II: Numerical simulations

This paper presents a global ocean implementation of a multi-component model of marine pelagic biogeochemistry coupled on-line with an ocean general circulation model forced with climatological surface fields (PELAgic biogeochemistry for Global Ocean Simulations, PELAGOS). The final objective is the inclusion of this model as a component in an Earth System model for climate studies. The pelagic model is based on a functional stoichiometric representation of marine biogeochemical cycles and allows simulating the dynamics of C, N, P, Si, O and Fe taking into account the variation of their elemental ratios in the functional groups. The model also includes a parameterization of variable chlorophyll/carbon ratio in phytoplankton, carrying chl as a prognostic variable. The first part of the paper analyzes the contribution of non-local advective–diffusive terms and local vertical processes to the simulated chl distributions. The comparison of the three experiments shows that the mean chl distribution at higher latitudes is largely determined by mixing processes, while vertical advection controls the distribution in the equatorial upwelling regions. Horizontal advective and diffusive processes are necessary mechanisms for the shape of chl distribution in the sub-tropical Pacific. In the second part, the results have been compared with existing datasets of satellite-derived chlorophyll, surface nutrients, estimates of phytoplankton community composition and primary production data. The agreement is reasonable both in terms of the spatial distribution of annual means and of the seasonal variability in different dynamical oceanographic regions. Results indicate that some of the model biases in chl and surface nutrients distributions can be related to deficiencies in the simulation of physical processes such as advection and mixing. Other discrepancies are attributed to inadequate parameterizations of phytoplankton functional groups. The model has skill in reproducing the overall distribution of large and small phytoplankton but tends to underestimate diatoms in the northern higher latitudes and overestimate nanophytoplankton with respect to picoautotrophs in oligotrophic regions. The performance of the model is discussed in the context of its use in climate studies and an approach for improving the parameterization of functional groups in deterministic models is outlined.     

上海洋山深水港中港区码头面层混凝土的现场试验研究

码头面层裂缝的产生与混凝土配合比直接有关,但还与码头结构型式和施工质量等有关。为现场监测码头面层裂缝的产生,选择洋山深水港区中港区码头面层的梁顶、板缝等有代表性的位置,埋入自制的19个应变传感器和2个温度传感器,采用计算机现场监测码头面层应变和温度变化情况。结果表明:板缝和梁顶处的应变较大,是易于形成裂缝的主要部位。应在该位置设置切缝以释放应力或增加钢筋等构造措施,并增加养护时间。     

长江口南汇边滩短期冲淤变化分析

南汇边滩位于长江口和杭州湾的交汇地带,受长江口和杭州湾北岸两股潮流的控制,近年来由于低潮滩促淤围垦工程导致其水流和泥沙运移、沉积和地貌发生了显著的变化。根据2006—2008年南汇边滩测图及2007年11月—2008年11月每个季度的9个断面测量资料,结合区域内的泥沙沉积特征,探讨南汇边滩对周边涉水围垦工程和流域来水来沙变异做出适应性地貌耦合过程之后的近期冲淤演变规律,着重探讨季节性冲淤特征。结果表明:年度上南汇东滩以淤长为主,南汇南滩以冲刷为主。不同季节南汇边滩冲淤变化过程存在很大差异:平面上,南汇边滩等深线夏、冬季以淤进为主,春、秋季以蚀退为主;垂向上,南汇东滩断面呈春夏秋冲淤交替、冬季淤积的态势,南汇嘴断面呈秋季冲刷、冬夏季淤积的态势,而位于南汇南滩的断面则呈秋冬季冲刷、春夏季淤积态势。南汇东滩沉积物粒径总体上较细,东滩与南滩交汇处的南汇嘴附近中值粒径相对较粗,南汇南滩浅滩沉积物颗粒中值粒径最粗。     

Exploring relationships between recruitment of European hake (Merluccius merluccius L. 1758) and environmental factors in the Ligurian Sea and the Strait of Sicily (Central Mediterranean)

This paper explores the relationships between the spatial patterns of the distribution of the young hakes of the year (YOY) and the oceanographical features in two areas of the Central Mediterranean (the Ligurian Sea and the Strait of Sicily), characterised by the occurrence of straits and channels. Comparative and correlative approaches were used to investigate coupling between biological and physical patterns. Density indices of the YOY were derived from annual trawl surveys from 1994 to 2004 in spring and autumn. Mean patterns of the YOY distributions were compared with the mesoscale oceanographical features reported in literature. No evident trends in recruitment strength were found in either areas. Inter-annual variability in YOY abundance in the Ligurian Sea was higher than in the Strait of Sicily. The location of nursery grounds in the study areas coincides with zones of relatively higher production, where upwelling and other enrichment processes regularly occur. The presence of predictable eddies and the frontal systems play a major role in the localization of nursery areas in the Strait of Sicily, maintaining their stable position throughout the years. The strongest transport of southern waters from the Tyrrhenian to the Ligurian Sea, due to the East Corsica Current, which is negatively correlated to winter North Atlantic Oscillation, is associated with the highest abundance of hake recruits in the nurseries of the Northern Ligurian Sea.