A study of time over threshold (TOT) technique for plastic scintillator counter

A new charge measurement method, time over threshold (TOT), has been used in some gas detectors lately. Here TOT is studied for TOF system, made of plastic scintillator counter, which can simplify the electronics of the system. The signal characteristics are measured and analyzed with a high quality oscilloscope, including noise, pedestal, signal amplitude, total charge, rise time and the correlation between them. The TOT and charge are related and can be fitted by some empirical formula. The charge measurement resolution by TOT is given and this will help the design of TOF electronics.     

非磁性微球掺杂对纳米磁流体场诱导双折射特性的影响

利用二氧化硅和聚苯乙烯非磁性微球掺入铁氧体纯磁流体中,制得了复合磁流体.定性地研究了复合磁流体在外磁场作用下的双折射与非磁性微球的种类、掺杂浓度以及纯磁流体自身浓度的关系.研究表明,不同浓度的纯磁流体掺杂等量的聚苯乙烯微球对其双折射随磁场的变化趋势影响不同;同一浓度的纯磁流体掺杂不同种类的非磁性微球,对其双折射的影响也...     

Growth and micromagnetic simulation of magnetite nanoparticles

Magnetite nanoparticles with different sizes and different assemblies were synthesized via hydrothermal method.Micromagnetic simulation shows the magnetite nanocubes with different sizes have different energy states,which determines the assembly mode.Magnetite nanocubes with the side length of 30-60 nm tended to be dispersed while both nanochains and dispersed nanoparticles were found to grow for the nanocubes with the side length less than 30 nm,which can be explained in the fact that the above two assembl...     

Measurements on diproton emission from the break-up channels of ~(23)Al and ~(22)Mg

Two-proton relative momentum distributions from the break-up channels 23Al→p+p+21Na and 22Mg→p+p+20Ne at an energy of 60-70 A MeV have been measured together with two-proton opening angles at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility. The results demonstrate the existence of diproton emission component from single-step 2He for highly excited 23Al and 22Mg.     

Nonsteady sink and source in a rotating fluid

The effect of the Coriolis force on the nonsteady two-dimensional sink or source flow has been studied theoretically. With the assumptions of incompressibility and invisddity of fluid, the equations governing the flow are still non-linear. However, a set of analytical and exact solutions is obtained for the velocity and pressure distributions. The result shows that no significant vortex flow can be induced by a source flow, the circulation produced there mainly is because the observer is moving with the rotating system; however, a sink will always induce a vortex, the strength of circulation in the sink flow is simply in proportion to the rotating speed of the system and the time integrated sink strength. As the system is under a constant rotating speed, the circulation will vanish only when the time integrated sink strength vanishes. Several special cases of sink strength are examined and their results are presented in this paper. The purpose of this study is mainly to relate the strength of circulation with the strength of sink and source. Consequently, it- can be applied to the weather forecast for hurricanes or tornadoes.     

黑鱾（Girellaleonina）淀粉酶与蛋白酶的活力研究

通过测定1＋龄黑鱾的胃、盲囊、肝脏和肠道4个消化组织中蛋白酶和淀粉酶活性,并研究其与温度及pH值的关系,可以为黑纪的合理投饵提供理论依据．实验设9个温度梯度（10～50℃）和14个pH缓冲液梯度（pH2．0～9．0）,用淀粉-碘显色法测淀粉酶活力,用福林-酚试剂法测蛋白酶活力．结果表明：黑纪盲囊、肠道中淀粉酶和蛋白酶活力均较高,最适温度为35℃,淀粉酶最高活力为每克鲜组织46．02U和42．61U蛋白酶最高活力为每克鲜组织156．52u和147．79U;胃中酶的最适温度为40℃,肝脏中淀粉酶温度要求稍低,最适温度为30℃,酶活力值也最低;胃淀粉酶和胃蛋白酶最适pH值分别为6．5和3．5,盲囊、肠道和肝脏组织中的最适pH值相近,为7．0-8．0．可以认为黑鲍胃中主要存在着酸性蛋白酶,胃是食物蛋白质初步分解消化的场所;Q10值充分反映了温度对消化酶活力的影响,当温度从10℃上升至20℃时。2种消化酶活力增幅显著,可作为开始投饵的温度指标．     

气候变化对浙江沿海风暴潮的影响

基于浙江沿海多个气象观测站和潮位观测站近50年的气温、潮位及风暴潮的资料,研究了气候变化背景下浙江沿海台风暴潮变化特征.分析表明,随着沿海地区年平均气温的上升,浙江沿海相对海平面、登陆台风、超警戒风暴潮、较大风暴增水、年极值高潮位等都呈现出上升或增多趋势;在此背景下,浙江沿海风暴潮灾害风险也随之增大,特别是2000年以来,登陆浙江沿海的台风个数和最大增水超过300cm的风暴潮次数都显著增多.对气候变化背景下浙江沿海风暴潮灾害的影响分析,将为今后风暴潮预警及防灾、减灾的应对提供重要的启示和参考.     

基于SWOT分析的宁波市高校图书馆信息服务社会化的发展策略研究

宁波市高校图书馆文献资源丰富、具有专业及资质优势, 但也存在缺乏社会化服务经验等问题. 据此, 采用SWOT分析法进行分析后得出的如下观点: 宁波市高校图书馆必须建立切实可行的战略决策, 利用自身优势, 为高校教学科研做好服务的同时, 积极为地方社会服务; 完善激励机制, 激发潜在需求; 重视宣传推广, 打造服务品牌; 善于合作, 实现共赢.     

提高综合滤波器鉴别率的一种有效方法

提出一种提高综合滤波器鉴别率的有效方法，其做法是：对样本集在等相关峰条件下求解综合滤波器的同时，使样本集的互补样本满足零件相关峰条件，此方法把训练模式类同所有其它模式类在映射空间的距离拉大，有效地提高了综合滤波器的鉴别率，以取自同一手指纹为样本集，求解综合鉴别函数后，建立了指纹的实时模式识别系统，实验结果表明本文提出的改进方法对提高综合滤波器的鉴别率是非常有效的。