Comparative Experiments on the Effect of Radar Data Assimilation and Increasing Horizontal Resolution on Short-term Numerical Weather Prediction

To examine the effect of radar data assimilation and increasing horizontal resolution on the short-term numerical weather prediction, comparative numerical experiments are conducted for a Huabei （North China） torrential rainfall event by using the Advanced Regional Prediction System （ARPS） and ARPS Data Anal- ysis System （ADAS）. The experiments use five different horizontal grid spacings, i.e., 18, 15, 9, 6, and 3 km,respectively, under the two different types of analyses： one with radar data, the other without. Results show that, when radar data are not used in the analysis （i.e., only using the conventional observation data）, increasing horizontal resolution can improve the short-term prediction of 6 h with better representation of the frontal structure and higher scores of the rainfall prediction, particularly for heavy rain situations. When radar data are assimilated, it significantly improves the rainfall prediction for the first 6 h, especially the locality and intensity of precipitation. Moreover, using radar data in the analysis is more effective in improving the short-term prediction than increasing horizontal resolution of the model alone, which is demonstrated by the fact that by using radar data in the analysis and a coarser resolution of the 18-km grid spacing, the predicted results are as good as that by using a higher resolution of the 3-km grid spacing without radar data. Further study of the results under the radar data assimilation with grid spacing of 18-3 km reveals that the rainfall prediction is more sensitive to the grid spacing in heavy rain situations （more than 40 mm） than in ordinary rain situations （less than 40 mm）. When the horizontal grid spacing reduces from 6 to 3 km, there is no obvious improvement to the prediction results. This suggests that there is a limit to how far increasing horizontal resolution can do for the improvement of the prediction. Therefore, an effective approach to improve the short-term numerical prediction is to combine the radar data assimilation with an optimal horizontal resolution.

Comparative Study of Micro and Nano Size WO3/E44 Epoxy Composite as Gamma Radiation Shielding Using MCNP and Experiment

The radiation shielding characteristics of 50wt% WO3/E44 epoxy composite in various gamma energies from 80 keV to 1.33 MeV are investigated via the MCNP code. Thus two scales are considered for WOa filler particles： micro and nano with sizes of i #m and 5Onto, respectively. The simulation results show that W03 nano particles exhibit a larger increase in linear attenuation coefficient in comparison with micro size particles. Finally, validation of simulation results with the published experimental data shows a good agreement.

A Comparative Experimental Study on the Blast-Resistant Performances of Single and Multi-Layered Thin Plates Under Close-Range Airblast Loading

The performance of multilayered thin steel plates subjected to close-range air blasts has been experimentally studied and compared with that of monolithic plates made of the same material and having equal mass. In present experiments, multilayered plates are in-contact four-layered thin steel plates and two types of deformation/failure modes were observed for them. Comparisons concerning deformation/failure modes, strain distributions and energy absorptions between the multilayered plate and its monolithic counterpart were conducted. It is found that the multilayered plate is much superior to its monolithic counterpart in the ability to deform against blast loading. Furthermore, under intense airblast loading, the multilayered plate can not only absorb much more energy but also effectively reduce the secondary destruction ability of structural fragments in comparison with its monolithic counterpart.

Squat,Stoop,or Semi-squat:A Comparative Experiment on Lifting Technique

There are actually no sufficient data for lifting technique assessment.A laboratory study was undertaken to determine the effect of 3 regular lifting techniques on erector muscle activation,cardiovascular strain and subjective response.Thirty student volunteers participated in the study,and were required to lift a weight with different techniques.Stoop-,squat-,semi-squat-lifting resulted in 3,2 and 1 time of the highest percentage of the maximum voluntary electrical activation(MVE%) respectively.In the same order,the lowest median frequency(MF) existed 1,1 and 2 times.Muscle fatigue was 4 times in squat,36 in semi-squat and 43 in stoop lifting.Heart rate was the highest in squat and lowest in stoop respectively,with a middle level in semi-squat lifting.It may be recommended to adopt mainly the semi-squat technique for daily lifting works.For heavy lifting,it should use the squat technique.Stoop lifting may also be used alternatively but for light things.

Comparative Experiment of Ground Cucumber Varieties for Open Field Cultivation

Seven ground cucumber varieties were cultivated in open field for the comparative experiment. The results showed that Texuan cucumber and Yantai ground cucumber had good commodity characters,good taste and high yield,and their output value exceeded 16 000 yuan/666. 7 m2,so they are more suitable for open cultivation in Yantai region. The next ones are Meiyu Diguawang and Aweishi ground cucumber.

A Comparative Study on Two Techniques of Reducing the Dimension of Text Feature Space

With the development of large scale text processing, the dimension of text feature space has become larger and larger, which has added a lot of difficulties to natural language processing. How to reduce the dimension has become a practical problem in the field. Here we present two clustering methods, i.e. concept association and concept abstract, to achieve the goal. The first refers to the keyword clustering based on the co occurrence of

不同液化判别方法在下辽河地区的对比分析

结合海城地震液化资料,选取四种具有代表性的液化判别方法,通过判别结果与地震液化资料的对比分析,得出各种判别方法的优劣。四种方法可归纳为利用规范和室内实验两大类。结果表明:规范方法,判定结果的准确率为42.8%;调整的规范方法,准确率为88%;室内实验的输入正弦波方法,准确率为88%;室内实验的地震波法,准确率为77%。规范方法优点方便快捷,缺点是利用规范提供参数准确率有限;室内实验方法优点是物理原理清楚,缺点是需要进行土层地震反应计算。由此说明,利用规范方法,并适当调整参数,可以有效提高液化判定准确率。

比较教学法在仪器分析实验教学中的应用

仪器分析实验是医学预防及医学检验等专业的重要实验课程之一。为提升本科生的创新实践能力,设计了分别利用高效液相色谱仪(HPLC)和超高效合相色谱仪(UPC2)测定复方阿司匹林片中乙酰水杨酸和咖啡因含量的实验,并将思政元素有机地融入其中。教学实践表明,通过对不同仪器原理、功能特点的比较学习,可以激发学生的实验兴趣和探索精神,增强学生解决问题的能力,进而提升学生的科学素养。

大管径Y型过滤器流动阻力特性数值模拟及实验研究

大管径Y型过滤器是区域供冷和供热领域常用的过滤装置,设计师在选型时往往仅关注滤网目数,而忽略对过滤器阻力损失的关注.为了探究大管径Y型过滤器阻力损失的影响因素,首先,采用数值仿真计算的方法,分别建立不同特征尺寸的三维Y型过滤器模型,并利用深圳市前海区域供冷系统中的过滤器实验平台验证模拟的准确性;其次,研究了不同特征尺寸对于改善大管径Y型过滤器阻力损失的影响情况,并针对特征尺寸进行灰关联度排序,结果表明,影响程度由大到小依次为:腔体出口尺寸>滤网透过率>腔体入口尺寸>腔体与管道轴线夹角>腔体中心筒径>腔体长度;最后,根据灰关联度排序,通过将过滤腔体筒径扩大至管道直径的1.25倍,将过滤腔体的长度延长至管道直径的1.20倍,将腔体出口尺寸扩大至管道直径的1.125倍,将腔体与管道轴线夹角扩大至55°,滤网透过率提高至43.83%,新设计了流动阻力特性更优的大管径Y型过滤器,CFD计算结果显示,新设计的过滤器与原过滤器相比,阻力损失下降了73.23%,可大幅降低流体输配能耗.针对CFD优化设计方法,利用尺寸相近的Y型过滤器开展了阻力特性对比实验验证.本研究为大管径Y型过滤器的优化设计及技术改造提供了理论依据.

超声波衍射时差法在海洋平台卷管焊缝检测上的应用

海洋石油平台钢桩、立柱、导管、隔水套管、拉筋等卷管结构的无损检测主要采用手工超声波检测(UT)或射线检测(RT),检测效率低下,存在辐射风险。为解决海洋平台卷管焊缝手工超声波检测效率低下及射线检测辐射安全的问题,提出将超声波衍射时差法(TOFD)应用到卷管焊缝检测上,根据标准规范设计加工TOFD对比试块,对已知人工缺陷进行TOFD与UT对比实验,对现场存在自然缺陷的卷管焊缝进行TOFD与RT对比实验,通过多次对比实验确定了TOFD扫查方式和工艺参数,验证了TOFD技术的可靠性以及高效性,最终将TOFD技术应用于海洋平台卷管焊缝检测,明显提高此类焊缝的检测准确度和检测效率,并且避免了射线检测的辐射风险。

基于不同功率的非能动安全壳热量导出系统实验研究

“华龙一号”非能动安全壳热量导出系统(passive containment heat removal system,PCS)和“玲龙一号”非能动安全壳热量导出系统设计原理相同,但系统功能和设计准则不尽相同。为了掌握影响系统换热能力和运行的关键因素,本文结合不同项目的特点,从综合性能实验需求和实验结果等方面,研究、分析“华龙一号”非能动安全壳热量导出系统与“玲龙一号”非能动安全壳热量导出系统设计中的典型现象,发现降低冷却水箱水位可以提升系统的换热能力、改变冷管段阻力对系统的换热能力更敏感和冷管段隔离阀关闭方案在开启时可能会有一定的风险,从而提出后续优化研究和设计中需要重点关注的影响因素。文中结论可用于指导相关系统设计工作。

Z比分数不同统计方法在实验室间比对试验结果评价中的比较

Z比分数是评定实验室间比对试验结果的重要方法。系统介绍了计算Z比分数的经典统计法、四分位数稳健统计法、迭代稳健统计法(算法A)和Q/Hampel稳健统计法。并以中国石化销售企业组织的某次实验室间比对试验92号车用汽油(VIB)硫含量数据为统计对象,比较了四种统计方法Z比分数评价结果的差异性。为实验室间比对试验选择合理有效的统计分析方法,提高实验室的检测能力和管理水平提供了参考。

蚕豆新品种引种比较试验初报

筛选出适宜种植的蚕豆新品种,对助推蚕豆产业高质量发展具有重要意义。以临潭当地常年种植的马牙蚕豆为对照,对引进的5个蚕豆新品种进行了引种比较试验和主要营养成分分析。结果表明,临蚕10号和青海13号产量均高于对照品种马牙蚕豆,折合产量分别为5962.98、5437.62 kg/hm2,分别较对照品种马牙蚕豆增产13.85%、3.82%,可在临潭县进一步种植。而青蚕14号由于蛋白质、粗纤维、碳水化合物、能量总体含量较高,可作为专用型品种在临潭县应用。

务川县辣椒引种比较试验

辣椒是贵州省务川县重要的经济作物,也是当地农业产业的重要组成部分。为筛选出适合务川县推广种植的优质高产辣椒新品种,对引种的12个辣椒品种的生育期、品种特性、产量及抗病性进行比较试验。试验结果显示,骄阳1号、骄阳2号和骄阳6号的全生育期分别为184 d、186 d和183 d,单果鲜质量分别为6.7 g、7.6 g和6.8 g,平均每667 m^(2)鲜椒产量分别为1305.67 kg、1368.42 kg和1418.44 kg。结果表明,此3个品种综合表现优异,抗病性强,属于大果型朝天椒,可在进一步试验示范的基础上进行大面积推广种植,但在生产过程中应注意青枯病、疫病、病毒病和炭疽病的防治。

德州地区小型西瓜品种露地种植比较

为了筛选适宜德州地区露地种植的小型西瓜品种,从出苗率、定植成活率、生长势、抗病性、果实性状及品质、产量等方面对参试西瓜品种进行比较。结果显示,ZXH出苗率和定植成活率较高,都在90%以上,果实发育期短为28 d,生长势最强,发病率最低为3.3%,中心糖和边糖含量梯度差最小,整体糖含量较高,单瓜重、小区产量、折合667 m^(2)产量最高。ZT2693-11出苗率稍低,但定植成活率高,生长势较强,发病率较低,果实发育期最短,只有26 d,果皮薄,果实为短椭圆形,中心糖含量10.20%,边糖含量9.00%,品质好,产量高,ZXH和ZT2693-11适合在德州地区推广种植。

设施内草莓品种在富阳地区引种对比

本研究通过对设施内草莓品种章姬、越丰、越秀、红玉、浙莓17进行农艺性状、果实性状、生育期与结果性状以及抗病虫特性的比较,为草莓在当地推广提供理论依据。结果表明,在杭州富阳地区草莓品种浙莓17采摘时间最早,同时兼具品质佳、连续结果能力强、单株产量较高、耐贮运的特点。红玉和章姬采收时间次之,其中章姬生长势最强,果实品质佳,但不耐贮运,而红玉每株产量较章姬和浙莓17高;越秀和越丰采收时间最迟,其中越丰果实品质佳,采收第一批果可溶性固形物含量最高,但不抗灰霉病,越秀采收时间最迟,单株产量最高的。5个草莓品种均有自己的优势和劣势,建议草莓生产中可根据物候期搭配合理种植,满足不同时期对草莓的需求。

将乐县优质稻新品种比较试验

为筛选适宜将乐县种植的优质稻新品种,2023年将乐县农业技术推广中心引进11个优质杂交稻新品种在古镛镇和平村进行比较试验。结果表明:浙大荃优1610、野香优6866、青香优261、爽两优138、泰两优27占等5个品种丰产性好、米质优、综合表现良好,可扩大试验示范;华浙优210生育期短、分蘖力强、结实率高、米质优,可作为双季晚稻试种观察。总结了参试品种的特征特性及产量表现。

碳/碳材料作为单晶炉发热体的研究

发热体作为单晶炉的唯一热源,是影响拉晶质量的重要部件。通过与传统石墨发热体材料进行对比实验,分别针对电阻率、电阻温度稳定系数、导热系数、力学性能、抗腐蚀性5个重要因素,结合自身的工艺进行比较,探究碳/碳材料作为单晶炉发热体的优劣势。

注意力分配、重大事故经历与政府安全生产治理——基于NCA与QCA混合研究

为探究政府安全生产治理绩效提升路径,基于前景理论和“技术—组织—环境”框架构建复合分析模型,对我国31个省(自治区、直辖市,不含港澳台)2005—2019年安全生产领域相关数据进行分析,借助必要条件分析与定性比较分析探究要素间的复杂因果效应。研究结果表明:数字治理能力和社会数字环境是政府安全生产治理绩效提升的关键瓶颈,符合“数字赋能治理”预期;注意力分配和重大事故经历起核心作用,结果支持注意力分配理论和概率赋权假说;“综合发力型”“领导重视型”和“组织推动型”是产生高绩效的3条等效路径,“镣铐起舞型”是低绩效路径。研究结果有助于揭示技术、组织、环境等多重条件对于政府安全生产治理的影响,可为安全生产领域内相关政策调整提供参考依据。