三种秸秆有机肥改良土壤次生盐渍化的效果及生物效应

通过盆栽实验的方法,研究了三种秸秆有机肥对次生盐渍化土壤的EC值、硝酸根离子含量和油菜生物量的影响。结果表明,M1有机肥显著增加油菜的生物量,但在一定程度上增加土壤盐分含量;M2有机肥的效果与M1有机肥效果趋势相似,但增加土壤中的盐分含量的程度要小的多;而施用秸秆肥料M3,在增加油菜生物量的同时显著降低土壤盐分含量,减轻了土壤的次生盐渍化程度。结果表明,三种秸秆有机肥均能提高油菜对盐渍化的耐受能力,增加其生物量。采用M3秸秆有机肥改良土壤盐渍化是一条有效途径,但其最佳施用量与土壤盐渍化程度有关,非盐渍化土壤施用过多M3肥料将降低生物量。     

焉耆盆地水资源开发与土壤次生盐碱化防控研究

焉耆盆地水土资源丰富,光热条件充分,是新疆农牧业生产的主要基地之一。但由于长期以来水土资源开发不当,导致本区土壤次生盐碱化日趋严重,严重影响了当地农业的持续发展,且其农业排水直接导致博斯腾湖的水质劣化。本文在分析区域土壤盐分分布的空间特征和土壤次生盐碱化产生的背景条件的基础上,提出了区域水土资源可持续开发的对策,并着重分析在该盆地细土平原带通过竖井灌排开发地下水以降低地下水位的必要性与可行性,从而推动该区农业的稳定发展和环境质量的逐步好转。     

A genetic algorithm with modified crossover operator and search area adaptation for the job-shop scheduling problem

The genetic algorithm with search area adaptation (GSA) has a capacity for adapting to the structure of solution space and controlling the tradeoff balance between global and local searches, even if we do not adjust the parameters of the genetic algorithm (GA), such as crossover and/or mutation rates. But, GSA needs the crossover operator that has ability for characteristic inheritance ratio control. In this paper, we propose the modified genetic algorithm with search area adaptation (mGSA) for solving the Job-shop scheduling problem (JSP). Unlike GSA, our proposed method does not need such a crossover operator. To show the effectiveness of the proposed method, we conduct numerical experiments by using two benchmark problems. It is shown that this method has better performance than existing GAs.     

山西太原污灌区农田土壤汞污染状况及其生态效应

本文测定了山西太原污灌区农田土壤中汞污染状况 ,并采用盆栽模拟的方法 ,研究了汞污染对土壤酶活性、土壤有效磷含量、小麦产量以及地下水质的影响 ,结果表明污水灌区土壤中汞的累积量明显高于清水灌区 ,随着汞污染程度的加重 ,对土壤酶活性及小麦生长的抑制作用也增强 ,长期利用污水灌溉 ,土壤中汞会下移 ,从而对浅层地下水造成污染     

Application of a genetic algorithm in solving the capacity allocation problem with machine dedication in the photolithography area

Wafer fabrication is a complicated manufacturing process with high process capability. Hence, maximizing machine capacity to meet customer deadlines is a very important issue in this field. This study proposes an integer programming model and a heuristic algorithm approach to solve the loading balance problem for the photolithography area in the semiconductor manufacturing industry. Considering process capability, machine dedication, and reticle constraints, we aim to minimize the difference in loading between machines. Process capability means that each product must be processed in machines that meet the process specification. Machine dedication means that if the first critical layer of a wafer is assigned to a certain machine, then the following critical layers of such wafer must be processed in this certain machine to ensure wafer quality. This research compares the results of two methods and finds the best parameter settings of the genetic algorithm (GA). The computational performance results of the GA shows that we can find the near-optimal solution within a reasonable amount of time. Finally, this research analyzes machine capability and reticle flexibility to determine the best percentage that can be used as reference for application in the semiconductor industry.     

Performance of multi-tasking and synchronization mechanisms in the programming language SR

High-level language primitives for concurrent programming exist in languages such as Ada and Modula-2. However, each of these languages provides only a single means for specifying multitasking and synchronization, essential in the implementation of concurrent systems. The SR language provides several mechanisms for specifying multi-tasking and synchronization, so it can be used to explore the performance of various communication techniques. This paper presents performance results for SR's multi-tasking and synchronization mechanisms and discusses the effects of the generated code, the run-time support and the hardware on these results. These results are compared with those for similar mechanisms in other languages, leading to some general conclusions about the performance of process communication primitives. These performance results can be used by programmers to make design choices that allow systems programs written in high-level languages to meet real-time performance specifications.     

遗传规划算法在化合物设计、筛选研究中的应用

采用计算机科学中新兴的遗传规划算法思想，结合化学物质的本质特点，运用进化操作来实现化合物的合成设计和筛选。文中针对算法运用讨论了函数集、终止集问题，通过计算元素组成的字符串的化合价的结果来确定适应度函数，既符合化学学科的本质规律，又满足了算法的要求。通过复制、交换和突变操作，经过多代次的进化终止，取得了满意的结果。文章还针对其实用性，从化学本质出发，提出了建议和研究方向。可以说本文是遗传规划在化学化合物合成筛选中运用的成功探索，同时也为进一步研究打下了坚实的基础。     

熔焊快速成型的截面填充与扫描算法研究

本文针对熔焊快速成型技术的特点,在对其截面填充的过程与轨迹规划详细研究的基础上,提出了一整套适合熔焊快速成型的截面填充算法。该算法首先用双向循环链表表示模型截面轮廓的边界,然后对这些截面轮廓进行内外轮廓的判定、复连通区域和单连通区域的判定、以及复连通区域剖分和单连通区域的单调划分,最终生成有限个单调区域。最后对这些单调区域进行填充扫描,并生成可用于熔焊快速成型的数控指令。     

Gender differences in computer attitudes and the choice of technology-related occupations in a sample of secondary students in Spain

The dearth of women in technology and ICT-related fields continues to be a topic of interest for both the scientific community and decision-makers. Research on attitudes towards computers proves that women display more negative computer attitudes than men and also make less intense use of technology and computers than their male counterparts. For this reason, the main aims of this study are threefold. Firstly, to analyze the existence of gender differences in three dimensions of computer attitudes in a group of 550 secondary students in Spain (mean of age = 15 years old; SD = 1.73). Secondly, to study the moderating influence of a group of contextual variables on those gender differences in computer attitudes. And thirdly, to examine the predictive role of computer attitudes on the intention to pursue technology-related occupations. Some of the analyses of variance carried out show more positive computer attitudes in boys than in girls. These differences are more salient among students coming from rural areas and the upper social class, who are also enrolled in the domain of technology in secondary education, and whose mothers have no occupation outside the home. Finally, simple logistic regressions were carried out in order to prove that all dimensions of computer attitudes predict the enrollment intentions to pursue technology-related occupations. Nonetheless, gender only moderates the relationship between the cognitive dimension of computer attitudes and the enrollment intentions to pursue technology-related occupations.     

甘肃高等教育信息资源建设的现状与问题分析

本文首先介绍了甘肃高等教育信息资源建设的现状,然后深入分析了甘肃高等教育信息资源建设中存在的主要问题,如观念问题、人才问题等,并在此基础上提出了相应的解决办法。     

可可西里湖泊水面面积与雪冰覆盖率相关分析

气候变化对青藏高原湖泊水面面积会产生很大的影响,雪冰覆盖作为气候变化的一个重要因素,也对青藏高原湖泊水面面积有一定的影响。利用遥感影像提取2009—2017年可可西里地区库塞湖及周边四湖(简称为四湖)的年水面面积,同时,利用2005—2016年的MODIS积雪产品,提取四湖集水区雪冰覆盖率,结合同期五道梁气象站点的逐月平均气温数据和降水量,对四湖水面面积变化与集水区雪冰覆盖变化规律及其与五道梁站气温与降水量之间的关系进行探讨。分析表明:1)卓乃湖2011年9月溃决后,4个湖泊的水面面积都发生较大的改变;2)2005—2014年期间,四湖集水区雪冰覆盖率总体呈小幅度增加趋势;3)卓乃湖溃决后,库塞湖及卓乃湖的水面面积与五道梁站年均气温的相关性显著提高,而库塞湖及卓乃湖的水面面积与四湖集水区雪冰覆盖率的相关性显著降低。