一座双板源钴源辐照装置的技术改造实例

根据对一座设计装源能力为2.96×1016Bq （80万Ci）的双板源钴源辐照装置的改造实例,阐述了改造的具体内容和特点,并通过改造前后的性能对比,对改造进行了利益代价分析。通过此次改造,辐照装置的产量提高了50％以上,给用户带来了可观的直接经济效益和长远的间接经济效益,表明本次改造是成功的,也具有一定的示范作用和推广价值。     

辐照装置剂量场最佳分布对源棒排布要求初探

辐照装置剂量场不均匀度的好坏直接影响到产品质量与照射成本 ,而空场不均匀度主要是由辐照装置源棒排布决定的。本文结合江苏里下河地区农科所 1 989年、1 993年、1 995年和 1 998年 4次增源情况 ,对环状辐射源、栅板状辐射源源棒排布方案的确定进行了探讨     

单板源静态堆码辐照工艺研究

本文从提高单板源静态辐照的剂量均匀性和源利用率的观点出发,通过对辐射场剂量率分布数据和常用堆码方式的分析,提出了象限对角位移法和复合象限位移法等堆码工艺,从而改善了辐照剂量不均匀度,并提高了源的利用率。     

不同排源方式对辐照产率的影响

利用自行设计的程序,计算了１６根源棒８种不同物源方式对辐照产率的影响。结果表明：在静态均匀场内辐照产品时,分散排源方式的辐照产率的高于集中排源。     

反馈系统在优化钴辐照装置安全性能方面的应用研究

为保证钴辐照装置的安全运行 ,运用控制论的一些基本原理在优化本单位辐照装置的安全性能方面进行了应用研究。实践证明 :该辐照装置的控制系统是安全有效的。本文较全面地对各种反馈系统的作用进行了分析 ,可对中、小型钴辐照装置控制系统的改造、优化钴辐照装置的安全性能方面作为借鉴     

单板源堆码辐照工艺研究

本研究结果表明：在货物静态堆码辐照过程中,采用单板源进行４ 工位辐照能有效降低立面剂量场的不均匀度,提高辐照质量,射线利用率达２２２７ ％ 。     

~(60)Co辐照装置自控系统的设计概述

60 Coγ辐照装置控制系统设计中PLC装置的应用及系统中的源架提升、安全联锁和悬链运行等控制模式进行了论述。与旧的控制方式比 ,提高了系统的精度和控制范围 ,引入了以辐照剂量控制为核心的运行程序。     

对旧有中小型γ源辐照装置控制系统的改造

本文提出了一种对旧有γ辐照装置控制系统进行改造、实现高度自动化的设计方案。     

提高60 Co辐照装置的经济效益探讨

本文用经济效益系数(Ε)评价60CO辐照装置的经济效益,影响因子有射线能量利用率(E)、辐照装置活度(CI)、时间利用率(T)、空间利用率(P)、最低有效吸收剂量(DMIN)、吸收剂量不均匀度(U)、单价(S)、运转成本(C)和收入I。分析结果为最重要的因素是收入,并举例说明了如何通过不断地开拓应用领域,创新辐照工艺提高收入。     

60Co辐照室增源后剂量场的剂量测定

在＾６０Ｃｏ辐照室增源１．８５ＰＢｑ后，启用前用Ａｇ２Ｃｒ２Ｏ７剂量计准确测量了源到辐照位置的重复性和辐照场的剂量率分布，以及辐照产品中吸收剂量的不均匀度，测量了ＵＶ－７５４分光光度计的摩尔消系数，结果表明，辐射场的剂量分布比较均匀，可以满足科研和辐照加工的需要。     

WHEAT RESPONSE TO NITROGEN SOURCE UNDER SALINE CONDITIONS

ABSTRACT

The influence of nitrogen (N) sources on biomass yield and nutrient uptake of wheat (Triticum aestivum L.) under saline conditions was studied in a greenhouse experiment. Six different forms of N {nitrate-N as Ca(NO₃)₂, urea-N [CO(NH₂)₂], ammonium-N as (NH₄)₂SO₄, nitrate-N+urea-N, nitrate-N+ammonium-N and a control (no N fertilizer)} were factorially combined with three levels of salinity to give a total of 18 treatments that were replicated three times. Each of the five levels of applied N was at the rate of 100?kg?ha^?1. The salinity levels (ECe) were 6.2 and 12.1?dSm^?1, denoted as S ₁ and S ₂ and untreated soil (S ₀), respectively. A basal dose of phosphorus (P) and potassium (K) was also applied. Five wheat plants were grown in each pot for six weeks. Data were collected for shoot and root biomass and shoot samples were analyzed for N, P, K, calcium (Ca), magnesium (Mg), sodium (Na), chloride (Cl), and micronutrients contents. Plant growth and nutrient uptake were influenced by both salinity and source of N. As expected, increasing salinity decreased dry matter production of shoot and root, whereas N application increased plant growth across all levels of salinity. The total dry biomass (shoot and root) of wheat was significantly higher in combined N treatments than in single sources. Irrespective of N forms most of the nutrient concentrations in the shoot was increased with increasing level of salinity. Among the fertilizers the concentration of cation was higher in nitrate-treated plants than in other forms of N. Ammonium-N and urea-N tended to inhibit the uptake of cations compared to nitrate-N under saline conditions. The trend for P and Cl concentration was almost opposite to that of cations concentration in the shoot. The uptake of nutrients seemed to be influenced by cation–anion balance in soil-plant system. Nitrogen concentration of shoot was greatly enhanced by all forms of N in the following order: Ni>NiAm>Am>NiUr>Ur>control. The interactive effect of salinity and fertilizer on iron (Fe), manganese (Mn), and zinc (Zn) contents was not consistent. Among the fertilizers the concentration of trace elements in the shoot was also not significantly different. It was concluded that the plant growth and nutrient concentration of shoot could depend upon N source and level of salinity. The mixed application of both ammoniacal and nitrate forms of N could possibly be conducive to plant growth in salt affected soils.     

NITROGEN SOURCE AFFECTS CRUNCHINESS,BUT NOT LETTUCE YIELD

While nitrogen (N) form affects growth and yield of many vegetables crops, previous studies suggested that N-form may affect lettuce (Lactuca sativa L.) quality more than growth and yield. The objectives of this research were to evaluate the effect of the N-source used as injection material on the field performance and sensory attributes of three lettuce types. Three lettuce types (Romaine, butterhead and looseleaf) where grown with plasticulture and sidedressed with weekly injections of calcium nitrate, potassium nitrate, or ammonium nitrate, each at a rate of 7 kg N ha^?1 week^?1. All lettuce type reached marketable size 49 days after transplanting. N-source effect on marketable yield and head number was not significant (P>0.05). After harvest, lettuce samples were prepared for sensory evaluation. In a quiet session, panelists (n=36) were instructed to rate each sample for bitterness, sweetness, crunchiness, and overall preference on a 9-cm Hedonic scale. Sensory ratings were similar for all three lettuce types. Panelist found that crunchiness of calcium nitrate-fed plants (4.8 cm) was significantly (P=0.05) higher than that of plants receiving potassium nitrate (4.4 cm) or ammonium nitrate (4.2 cm). These results suggest that while growers may use ammonium nitrate because of its cost, they should consider using calcium nitrate to enhance lettuce crunchiness.     

小型钴源扩容屏蔽防护技术与环境评价

总结了宁夏农林科学院6 0 Co辐照室 1 997年成功进行了扩容倒装源的经过 ,论述了扩容方案、防护屏蔽、安全操作程序、剂量监检及注意事项     

一种安全可靠易制作的60Co源迫降装置

笔设计的一种^60Co放射源迫降装置，在本所辐照室技术改造和多年应用实践中，证明其安全、可靠、易制作，避免了几次因电源倒相或定位器失灵而造成的事故。     

VERMICOMPOSTING AS A NITROGEN SOURCE IN GERMINATING KIDNEY BEAN IN TRAYS

This study assessed the effectiveness of vermicompost as a germination media and nitrogen source for kidney bean Phaseolus vulgaris L. Five treatments were tested, based on the addition of increasing quantities of barren soil to vermicompost, and irrigated with four treatments of increasing urea-water solution. Chemical analysis of the different mixtures of vermicompost and barren soil were made. Percentage germination, plant growth, and foliar nitrogen assimilation were measured. Bean seeds in vermicompost germinated earlier than those planted in barren soil, but germination was less than 60% in trays with 85% and 100% vermicompost. Plants in vermicompost were taller and appeared to be healthier-looking. Plants with 0%, 50% and 85% vermicompost concentrations assimilated about 4 mg·L^?1 more nitrogen than other treatments (25% and 100%). Plants in the 85% vermicompost mixture had the best response to nitrogen assimilation.     

太湖上游地区面源污染氮素入湖量模拟研究

以太湖上游地区为研究对象,通过TM/ETM解译获取土地利用信息,应用IDRISI软件的水文分析模块,对太湖上游地区进行流域划分,选择代表性小流域进行野外监测,分析流域土地利用与河流水质的联系,估算林地、耕地产出径流的面源污染总氮浓度特征;在此基础上采用代表性流域实测参数与分布式水文模型相结合的思路,开发基于单元格网的面源污染模拟模型,应用1980~2000年水文站实测序列对模型进行率定和校验,模拟太湖上游地区面源污染总氮的空间分布及入湖量。研究结果显示,太湖上游地区林地产出径流的总氮浓度参数为0.778 mg L-1,耕地产出径流的总氮浓度参数为2.518 mg L-1。模型及参数在太湖上游地区具有较好的应用效果,验证区径流模拟的平均误差为13%,总氮输出量模拟的平均误差为11.6%。应用模型估算太湖上游面源污染总氮入湖量为7 632 t a-1,约占总入湖量的40.8%。研究区内不同土地利用类型的面源污染总氮输出差异较大,其中耕地面源污染总氮输出量为4 289 t a-1,占面源污染输出总量的56.20%;林地和城镇用地面源污染总氮输出量分别为1 849 t a-1和1 270 t a-1,占面源污染输出总量的24.22%和16.64%。