A survey of nitrate and nitrite content of fruit and vegetables grown in Slovenia during 1996-2002

Monitoring of nitrate (NO₃^-) and nitrite (NO₂^-) content in agricultural products in Slovenia has been carried out since 1996. The results of monitoring over the period 1996-2002 are presented. During this time 924 samples of 14 different agricultural products (potato, lettuce, apples, carrot, silage maize, cabbage, grapes, peaches, string beans, cereals, pears, cucumbers, strawberries and tomato) were analysed. The samples were taken at the time of maturity directly from growing sites and they were analysed using segmented flow analysis. The average nitrate contents were the highest in lettuce (1074 mg kg^-1), cabbage (881 mg kg^-1), string beans (298 mg kg^-1) and carrot (264 mg kg^-1), and they were moderately high in potato (158 mg kg^-1), silage maize (122 mg kg^-1), strawberries (94 mg kg^-1), cucumbers (93 mg kg^-1) and cereals (49 mg kg^-1). Low nitrate contents (below 6 mg kg^-1) were found in fruit (grapes, peaches, apples and pears) and tomato. With the exception of cereals (8.9 mg kg^-1), apples (1.5 mg kg^-1), potato (1.2 mg kg^-1) and pears (1.0 mg kg^-1) the content of nitrites did not exceed 0.5 mg kg^-1. It may be concluded that the results of the monitoring were in most cases similar to the results of investigations obtained in other countries.     

地域通信网的干扰技术研究

本文在分析地域通信网结构及组成的基础上,研究了对地域通信网实施的节点破坏、末端信息封锁、局部阻塞瘫痪等对抗方法,并使用干扰地域通信网的程度、节点干扰率、末端节点封锁率和传递信息误差率等指标对干扰效果进行评估。     

榆林气田气井废弃条件的确定

榆林气田是典型的低渗透气田，要准确计算其采收率和可采储量，必需确定气井的废弃条件。传统方法对气井的废弃地层压力进行计算时，由于忽视了开发过程中产能方程的变化，造成计算结果存在一定的误差。根据气井废弃地层压力的相关理论和计算方法，考虑了对气井产能方程影响较大的参数的变化，结合榆林气田气井矿场实际，推导出了适合榆林气田计算气井任意时刻二项式方程系数的公式，进而得到气井废弃时的稳定二项式方程。根据垂直管流法计算得到废弃井底流压，从而得到可靠的气井废弃地层压力，再结合经济评价即可确定气井的废弃产量。实例计算表明，新方法实用、有效，更切合气田实际。     

An algebraic method for processing colored images

An 8-valued commutative ring is developed to process colored images. Algebraic operators are defined to perform a number of operations such as the extraction of the primary colors and contours of different colors.     

An implementation for a fast public-key cryptosystem

In this paper we examine the development of a high-speed implementation of a system to perform exponentiation in fields of the form GF(2 ⁿ ). For sufficiently large n, this device has applications in public-key cryptography. The selection of representation and observations on the structure of multiplication have led to the development of an architecture which is of low complexity and high speed. A VLSI implementation has being fabricated with measured throughput for exponentiation for cryptographic purposes of approximately 300 kilobits per second.     

��Ȼ����Һ���÷����̽

求文针对我国天然气凝液如何利用问题,结合新技术进展,进行了初步探讨,认为原料较多的场合,应以催化脱氢或芳构化作为当前的主要加工方向。对原料较少的场合,也提出一些看法。     

Internal drift effects on the diffusion of Ag in CdTe

Anomalous diffusion profiles of Ag in single crystalline CdTe were observed using the radiotracer ¹¹¹Ag. The diffusion anneals were performed at 800 K under Cd or Te vapor and in vacuum with low Ag concentrations. The measured Ag profiles directly reflect the distribution of the self-interstitials and vacancies of the Cd sublattice and are the result of chemical self-diffusion which describes the variation of the deviation from stoichiometry of the binary crystal as a function of depth and time. It turned out that the spread of the Ag dopant essentially is determined by the drift of the charged defects within the electric field caused by the distribution of the extrinsic and intrinsic defects.     

3DFD Simulation of Asymmetric Wave Field by Side-wall Acoustic Tool in Open and Cased Wells

1. Introduction Side-wall acoustic logging tools, such as the Segmented Bond Tool (SBT) from Baker Atlas and the tools for open hole measurements, utilize acoustic transducers mounted on six pads to make compensated acoustic velocity and attenuation measurements which are not affected by mud weight, gas cut, fast formation effects, casing surface conditions or reasonable tool de- centralizing. Studies on the wave fields generated by these tools are very important to tool design and data int…     

锥形凸台成形的一种叠加滑移线场力学模型

分析了锥形凸台在不同体积成形工艺中的成形机理，基于模块化思想将锥形凸台的成形过程划分为挤压成形与角部充满两个特征时段；将上述两个特征时段的滑移线场力学模型有机联结，构建了锥形凸台成形过程的一种叠加滑移线场力学模型；介绍了叠加滑移线场力学模型的应力场与变形力的求解方法。该模型丰富了金属体积成形过程的特征单元库，可套用于局部成形的应力场与变形力求解，实现局部成形的模具优化设计。     

基于遗传算法的工作辊温度场参数优化模型

针对热连轧机工作辊热辊形计算中温度场模型的热交换等参数难以确定的问题 ,建立了基于遗传算法的参数优化模型 ,可以解决复杂条件下的热参数的求解问题。利用优化参数计算的轧辊温度场与实际测量结果一致。