土粒度分维的确定方法探讨   总被引：5，自引：1，他引：4  

张凌 《水文地质工程地质》1999,26(5):43-45

本文通过对目前国内外研究土的粒度分维的三种方法的理论进行分析并一实际土样进行了比较,得到利用质量法求得土的粒度是三维方法中最方便实用的方法。  相似文献   

美洲鳗鲡(Anguilla rostrata)养殖尾水高效处理与水循环养殖技术研究与应用     

王行  江兴龙  王泽旭  刘勇 《海洋与湖沼》2023,54(5):1498-1506

通过构建由组合三维电极移动床生物膜反应池、生物膜反应池、臭氧紫外线杀灭微生物池等组成的养殖尾水高效处理系统,应用于工厂化美洲鳗鲡(Anguillarostrata)养殖尾水的集约化高效净水处理,并对系统的排放水循环利用于美洲鳗鲡的精养殖。经140 d的试验应用,结果表明:该系统日平均处理养殖尾水3 000m³,水力停留时间(HRT)为6.2h,经系统处理后的出水总磷浓度为(0.140±0.020) mg/L、总氮浓度为(0.671±0.114) mg/L、氨氮浓度为(0.104±0.050) mg/L、高锰酸盐指数为(2.81±0.44)mg/L,pH为(6.22±0.18)。系统出水水质符合《地表水环境质量标准》(GB3838-2002)的Ⅲ类水。系统出水循环利用于美洲鳗鲡精养殖(处理组)的平均单产55.5 kg/m3,较工厂化美洲鳗鲡养殖模式(对照组)提高52.5%;处理组的结束尾重、存活率、增重倍数和特定生长率分别高于对照组44.9%、5%、64.8%和37.5%,饲料系数低于对照组15.7%。该系统具有水处理效率高、出水水质稳定良好、成本低、节约水资源、环...  相似文献   

差异沉降法中倾斜量的正算与反演     

陈德标 《测绘科学》2010,35(4):68-70

针对差异沉降法倾斜观测数据的处理,及与其他方法所得成果的比对需要等问题,本文理论推导了任意两方向沉降差正算监测体最大倾斜角、倾斜方向的可靠公式,并用算例验算其正确性;由于差异沉降法一般不能反映0期监测时的倾斜量,本文提出将当前倾斜量作基础沉降差反演,导出通式,求得"原始高程",使后期沉降差完整反映监测体倾斜状态成为可能;最后通过试验验证本文方法。  相似文献   

Determination of dead-time in photon counting photometers by a polarimetric method     

David Clarke  Gerry Deighan  Gillian Fry  Susan Goodsir  Donald Macleod 《Astrophysics and Space Science》1996,239(2):229-235

Experiments are described which demonstrate that the dead-time constant associated with a photon counting stellar photometer/polarimeter is readily determinable by the application of the Malus law. It is also proposed that corrections for dead-time losses should be applied by an iteration technique to the exact equation rather than using the available approximation formulae.  相似文献   

多源日志存储和分析在网络事件关联中的实际应用     

孙毅  赵泽宇  闫华 《中国海洋大学学报(自然科学版)》2008,(Z1)

网络管理要对网络事件有全面认知。目前网络管理的常用手段主要依靠对所有网络设备和网断的系统信息检测和读取信息,而网络信息庞杂且时刻变化,对信息存储和解读提出了很高的要求和挑战。为了解决上述问题,基于Loglog算法提出了1种全新的网络运行日志存储和恢复算法,并且结合实际运行环境给出1个应用模型,扩展网络管理和维护的时间跨度和空间维度。同时,算法结合网络日志的特点加之最大熵方法的过滤器,并在网络认知关联上有实际的应用,对网络信息挖掘有理论联系实际的意义。  相似文献   

Design Research on Drive System of Underwater Tapping Machine     

喻开安 《中国海洋工程》2009,23(1)

The underwater tapping machine is composed of a center bit,a tapping cutter,a sesl box,a main drive box,aboring bar assembly,a envelop,a gear case,a counter and so on.The drive system in underwater tapping machine consists of a worm drive,a gear drive system and a screw drive.The worm drive is in the main drive box.The worm is connected with a hydraulic motor and driven by the hydraulic motor.The gear drive system is a combined gear train which is the combinations of the fixed axes and differential gear train in the gear case.On the one hand,by means of the fixed axes gear trains the turn and power of transmission shaft are transferred to the boring bar and the screw rod,causing differential tam between the boring bar and the screw rod.On the other hand,the turns of the boring bar and the screw rod are transferred to the differential gear train.The differential gear train is used to drive a special counter to count axial travel of the boring bar.The screw drive is composed of a feed screw and a nut on the boring bar.There is the differential turn between the boring bar and the feed screw.By means of the nut,the boring bar can feed automatically.With the movement of the sliding gear 7 in the gear case,the designed drive system can also be provided with the ability of fast forward and fast backward movement of the boring bar in its idle motion,restdting in the increase of the tapping efficiency.  相似文献   

珠江口沉积物210Pb分布特征及环境意义   总被引：2，自引：0，他引：2  

刘志勇  潘少明  程功弼  李向东 《沉积学报》2010,28(1):166-175

根据珠江口及其邻近海域中的14个沉积柱样的210Pb随深度分布的测量数据以及210Pb过剩衰减法的原理,建立了基于傅立叶级数的变沉积速率模型,对珠江河口近50年来河口沉积物的沉积序列进行了分析。分别对各柱样的210Pb数据使用变沉积速率模型进行计算,获得了柱样更切实的沉积速率变化过程并分析沉积速率、年代计算结果与同时期内沉积环境之间的关系,结果表明:珠江口不同站位的沉积速率差异很大,几个站位的整体平均沉积速率分别是,7.25 cm/a,5.36 cm/a,3.26 cm/a,3.03 cm/a,1.58 cm/a;沉积速率的变化与同时期发生在区域内的洪水、风暴潮、人类活动、河口演变等一系列综合因素有较好的对应关系,这说明使用基于傅立叶级数的变沉积速率模型得到的210Pb沉积速率变化的垂直分布能够解释其对应时段内的沉积环境,此模型亦可为其它河口区域的210Pb沉积速率计算提供借鉴。  相似文献   

OPTIMA: A Photon Counting High-Speed Photometer     

C. Straubmeier  G. Kanbach  F. Schrey 《Experimental Astronomy》2001,11(1):157-170

OPTIMA is a small, versatile high-speed photometer which is primarily intended for time resolved observations of young high energy pulsars at optical wavelengths. The detector system consists of eight fiber fed photon counters based on avalanche photodiodes, a GPS timing receiver, an integrating CCD camera to ensure the correct pointing of the telescope and a computerized control unit. Since January 1999 OPTIMA proves its scientific potential by measuring a very detailed light-curve of the Crab Pulsar as well as by observing cataclysmic variable stars on very short timescales. In this article we describe the design of the detector system focussing on the photon counting units and the software control which correlates the detected photons with the GPS timing signal. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

多能谱X射线成像技术及其在CT中的应用   总被引：1，自引：0，他引：1  

郝佳  张丽  陈志强  邢宇翔  康克军 《CT理论与应用研究》2011,20(1):141-150

随着探测器技术的不断发展,具有能谱分辨能力的光子计数探测器成为人们研究的焦点,并在X射线成像领域开始得到应用.使用该种探测器,可以将具有较宽能谱分布的X射线分为不同的能区分别进行计数,获得详细的能谱信息及不同能量射线的衰减信息,由此引出了"多能谱成像"的概念.本义介绍了近些年来光子计数探测器技术的发展及其在X射线成像中...  相似文献   

Effect of size grading on the growth performance of shortfin eel (Anguilla australis) during its yellow stage     

JA Hirt-Chabbert  A Sabetian  OA Young 《新西兰海洋与淡水研究杂志》2014,48(3):385-393

It is generally believed that size grading in a fish farm improves the total biomass output, because it will minimise the stress imposed by larger individuals over small individuals, resulting in higher feed intake and growth rate. The objective of this study was to evaluate the effect of size grading on individual growth performance of yellow New Zealand shortfin eel (Anguilla australis). A 109 day trial was conducted in a recirculation aquaculture system (RAS) with 103 eels of similar initial weight (101 ± 12 g). All eels were individually marked by PIT (passive integrated transponder) tags. On day 42, eels were graded to establish the following groups: only small eels (S-graded ≤ 135 g), only large eels (L-graded > 135 g), and small and large eels together (S-ungraded and L-ungraded). The large eels showed better specific growth rate (SGR), feed intake (FI) and feed conversion ratio (FCR) than the small eels. Nevertheless, no significant differences were found either between L-graded and L-ungraded or between S-graded and S-ungraded. The age of eels was not significantly different between groups. These findings suggest that the individual growth rate performance of the eels is not primarily a consequence of social interaction among tank-mates.  相似文献