基于Pro/E的渐开线圆柱齿轮参数化实体设计   总被引：1，自引：0，他引：1  

范晓珂 《煤田地质与勘探》2006,34(5):78-80

在Pro/E环境下分析了渐开线圆柱齿轮三维造型的特征,应用Program模块进行二次开发,实现了全液压钻机回转器渐开线圆柱齿轮三维参数化实体设计,有效地提高了设计效率。   相似文献   

基于MATLAB的液压钻机减速器多目标优化设计          下载免费PDF全文

陆惠明 《探矿工程》2012,39(3):23-26

介绍了利用MATLAB计算软件对液压钻机减速器优化设计的方法,即在保证其总传动比和承载能力下,以其齿轮中心距最小、齿宽最小为多目标,得到合理的液压钻机减速器参数。经优化后的齿轮比原设计目标值减少4．56％,中心距减少5．94％。  相似文献   

SP-I-01型全液压顶驱齿轮副振动分析     

王四一  高科  赵江鹏 《探矿工程》2013,40(6):14-17

振动会对齿轮副正常稳定工作产生影响。齿轮副的设计过程中要使其固有频率避开工作频率。通过对SP-I-01型全液压顶驱传动齿轮副进行振动分析,得出了齿轮副前六阶的固有频率及对应的振型图,并计算出其最高工作频率,与其固有频率进行对比,得出了其最高工作频率低于其最低阶的固有频率,符合设计要求。  相似文献   

Conservation of vaquita marina in the Northern Gulf of California     

Sara Avila-Forcada  Adán L. Martínez-Cruz  Carlos Muñoz-Piña 《Marine Policy》2012,36(3):613-622

Vaquita marina, a small species of porpoise endemic to the Northern Gulf of California in Mexico, is the world's most endangered cetacean species. With the purpose of preserving vaquita, the Mexican government launched PACE-Vaquita in 2008. This voluntary program offers an innovative schedule of compensations: as in a payment-for-conservation program, PACE-Vaquita compensates for temporary reductions in fishing effort; as in a program to accelerate technology adoption, PACE-Vaquita compensates for switching to vaquita-safe fishing methods; and as in a buyback program, PACE-Vaquita compensates fishermen for a permanent exit from fisheries. This paper seeks the factors explaining fishermen's participation in PACE-Vaquita during its first year of operation. Analysis is carried out through a multinomial logit specification on a data set collected one week after the enrollment deadline. This paper shows that fishermen with skills in alternative economic activities more likely quit fishing, and fishermen with relatively less productive vessels more likely switched to vaquita-safe fishing methods. Discussion of public policy implications is provided.  相似文献   

Incidence of marine debris and its relationships with benthic features in Gray's Reef National Marine Sanctuary, Southeast USA     

Bauer LJ  Kendall MS  Jeffrey CF 《Marine pollution bulletin》2008,56(3):402-413

Gray's Reef National Marine Sanctuary (GRNMS) is an increasingly popular site for recreational fishing and diving in the South Atlantic Bight (SAB). As a result, there has been heightened concern about potential accumulation of marine debris and its consequent effects on sanctuary resources. Field surveys were conducted at GRNMS in 2004 and 2005 to provide a spatially comprehensive characterization of benthic communities and to quantify the distribution and abundance of marine debris in relation to bottom features. The spatial distribution of debris was concentrated in the center of the sanctuary and was most frequently associated with ledges rather than other bottom types. On ledges, the presence and abundance of debris was significantly related to observed boating activity and physiographic features including ledge height, ledge area, and percent cover of benthic organisms. The results from this study will aid managers in optimizing cleanup efforts and long-term monitoring of debris accumulation patterns at GRNMS and other hard bottom areas in the SAB.  相似文献   

小口径涡轮钻具减速器非对称齿轮弯曲强度分析          下载免费PDF全文

张翔  周琴  张蔚  张凯 《探矿工程》2020,47(4):80-86

小口径涡轮钻具减速器是小井眼深井钻探钻具的重要部件,具有体积小、承载大的特点。采用非对称齿轮代替传统齿轮是提高减速器承载能力的有效手段。非对称齿轮两侧的齿根圆角半径和压力角是区别于对称齿轮的关键参数,通过改变齿轮的齿形结构进而影响了齿轮的齿根弯曲强度。为了进一步研究齿根圆角半径和工作侧压力角对齿根弯曲应力的影响规律,以φ127 mm涡轮钻具减速器中太阳轮为研究对象,建立非对称齿轮的受力模型,基于平截面法得到非对称齿轮齿根弯曲应力的理论计算公式,并通过有限元法对对称齿轮和非对称齿轮进行对比分析,仿真结果表明：增大齿根圆角半径能增大齿轮齿根过渡曲线的曲率半径,从而改善齿根处的应力集中;工作侧压力角的增大能有效降低齿根弯曲应力,但压力角超过一定值时,齿根弯曲应力逐渐趋于稳定。理论分析和仿真结果基本吻合,研究结果可以为优化减速器非对称齿轮的主要参数提供依据和参考。  相似文献   

垦西特稠油化学降粘机理的研究   总被引：10，自引：1，他引：9       下载免费PDF全文

陈艳玲  胡江 《地球科学》1998,23(6):605-609

详细研究了胜利油田垦西特稠油中的胶质、沥青质用降粘剂处理前后的红外特征吸收峰和透射电镜照片的变化。由红外光谱数据和透射电镜分析可知,降粘剂分子借助强的形成氢键的能力和渗透、分散作用进入胶质和沥青质片状分子之间,破坏了胶质、沥青质分子平面重叠的聚集体,使聚集结构变得疏松,表明聚集有序性降低是稠油降粘的主要机理。  相似文献   

Species Composition and Gear Characteristics of the Macrobrachium Fishery of the Cross     

Francis M. Nwosu 《青岛海洋大学学报(英文版)》2010,(1):71-75

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Out of sight but not out of mind: Harmful effects of derelict traps in selected U.S. coastal waters     

《Marine pollution bulletin》2014,87(1-2):19-28

There is a paucity of data in the published literature on the ecological and economic impacts of derelict fishing traps (DFTs) in coastal ecosystems. We synthesized results from seven NOAA-funded trap fisheries studies around the United States and determined that DFT-caused losses to habitat and harvestable annual catch are pervasive, persistent, and largely preventable. Based on this synthesis, we identified key gaps to fill in order to better manage and prevent DFTs. We conclude with suggestions for developing a U.S. DFT management strategy including: (1) targeting studies to estimate mortality of fishery stocks, (2) assessing the economic impacts of DFTs on fisheries, (3) collaborating with the fishing industry to develop solutions to ghost fishing, and (4) examining the regional context and challenges resulting in DFTs to find effective policy solutions to manage, reduce, and prevent gear loss.  相似文献   

Tide Model CST1 of China and Its Application for the Water Level Reducer of Bathymetric Data     

Jun Xu  Jing-Yang Bao  Chuan-Yin Zhang  Xing-Hua Zhou 《Marine Geodesy》2017,40(2-3):74-86

ABSTRACT

The performance of global tide models in China's seas is far worse than in deep water, owing to generally larger and more complex tides. An ocean tide model (named CST1) was developed by Princeton Ocean Model (POM) and blending assimilation technique, which includes 13 major constituents with a 1.2' × 1.2' spatial resolution. The nautical charts over the Chinese continental shelves and ETOPO1 database are used to generate the bathymetric grid model. The bottom friction coefficient is parameterized through a linear dependency on the depth of each grid. The weight parameter in blending assimilation is a function of the amplitude of constituent. Compared with 33 tide gauges along the Chinese coastline, the Root Sum Square (RSS) error of 8 major constituents is 12.09 cm, and the RSS of 4 major constituents (M2, S2, K1, O1) is 10.76 cm. CST1 with spatially interpolated residual water level was used to provide water level reducers for bathymetric survey. An example near amphidromic point of semi-diurnal constituents in the Yellow Sea demonstrated its process. Assessment showed that it can meet the required accuracies of standards of hydrographic surveys in China. The application proved that CST1 can predict adequately precise astronomical tide level, and is potentially economical and the best approach to provide water level reducers, although some checks should be made in survey planning stage.  相似文献