The role of domain knowledge in requirements elicitation via interviews: an exploratory study

Requirements elicitation is the first activity in the requirements engineering process. It includes learning, surfacing, and discovering the requirements of the stakeholders of the developed system. Various elicitation techniques exist to help analysts elicit the requirements from the different stakeholders; the most commonly used technique is the interview. Analysts may have domain knowledge prior to the elicitation process. Such knowledge is commonly assumed to have positive effects on requirements engineering processes, in that it fosters communication, and a mutual understanding of the needs. However, to a minor extent, some negative effects have also been reported. This paper presents an empirical study in which the perceived and actual effects of prior domain knowledge on requirements elicitation via interviews were examined. The results indicate that domain knowledge affects elicitation via interview in two main aspects: communication with the customers and understanding their needs. The findings provide insights as to both the positive and negative effects of domain knowledge on requirements elicitation via interview, as perceived by participants with and without domain knowledge, and show the existence of an actual effect on the course of the interviews. Furthermore, these insights can be utilized in practice to support analysts in the elicitation process and to form requirements analysis teams. They highlight the different contributions that can be provided by analysts with different levels of domain knowledge in requirements analysis teams and the synergy that can be gained by forming heterogeneous teams of analysts.     

Formulating Portland cement–reactive alumina blend through thermodynamic modeling to prevent the alkali–silica reaction

This study aims to formulate solid and aqueous compositions of hydrated Portland cement incorporated with reactive alumina (RA) via thermodynamic modeling, with the goal to prevent alkali–silica reaction (ASR). Based on SEM/EDS point analysis, the uptake of Al into C–S–H was corrected in the thermodynamic modeling to improve the accuracy. The predicted solid and aqueous compositions were validated by means of XRD, TGA, and ICP. An accelerated mortar bar test was also carried out to confirm the ASR mitigating efficiency, and a preliminary relationship among the ASR expansion, solid assemblage, and aqueous species was established. The critical content for RA is around 5.75% in the studied systems, above which katoite precipitates, resulting in increased Al concentration in the pore solution (∼0.8 mmol/L); hence, ASR can be effectively inhibited.     

Linearization of logical functions defined by a set of orthogonal terms. I. Theoretical aspects

Consideration was given to the linearization of logical functions defined by a set of pairwise orthogonal terms. The linearization is carried out by computing the autocorrelation functions. Proposed was a method consisting of (i) calculation of the autocorrelation function in the space of orthogonal terms, (ii) generation of the corresponding matrix of linear transformation, and (iii) the linear transformation proper of the variables in the space of orthogonal terms. Complexity of the proposed method and its effectiveness were estimated. Effectiveness was verified by a series of experiments with standard benchmarks. The distinctions of the proposed method from other existing methods of linearization were examined.     

事故工况限额供热环状热网水力工况研究

结合工程实例,建立管网水力工况模型并进行水力工况分析。对处于不同位置的管段发生事故时管网流量变化规律进行预测研究,经计算获得管网限额供热时最大限额流量系数,以及各事故工况下热力站入口阀门相对开度。     

Legume,cropping intensity,and N-fertilization effects on soil attributes and processes from an eight-year-old semiarid wheat system

In the North American northern Great Plains (NGP), legumes are promising summer fallow replacement/cropping intensification options that may decrease dependence on nitrogen (N) fertilizer in small grain systems and mitigate effects of soil organic matter (SOM) losses from summer fallow. Benefits may not be realized immediately in semiarid conditions though, and longer-term effects of legumes and intensified cropping in this region are unclear, particularly in no-till systems. We compared effects of four no-till wheat (Triticum aestivum L.) cropping systems–summer fallow–wheat (F–W), continuous wheat (CW), legume green manure (pea, Pisum sativum L.)—wheat (LGM–W), and pea–wheat (P–W)—on select soil attributes in an 8-year-old rotation study, and N fertilizer effects on C and N mineralization on a duplicate soil set in a laboratory experiment. We analyzed potentially mineralizable carbon and nitrogen (PMC and PMN) and mineralization trends with a nonlinear model, microbial biomass carbon (MB-C), and wet aggregate stability (WAS). Legume-containing systems generally resulted in higher PMC, PMN, and MB-C, while intensified systems (CW and P–W) had higher WAS. Half-lives of PMC were shortest in intensified systems, and were longest in legume systems (LGM–W and P–W) for PMN. Nitrogen addition depressed C and N mineralization, particularly in CW, and generally shortened the half-life of mineralizable C. Legumes may increase long-term, no-till NGP agroecosystem resilience and sustainability by (1) increasing the available N-supply (~26–50 %) compared to wheat-only systems, thereby reducing the need for N fertilizer for subsequent crops, and (2) by potentially mitigating negative effects of SOM loss from summer fallow.     

工程机械大型结构件生产工艺探讨

大型结构件是工程机械的重要组成部分,关系着工程机械的外观质量和整机性能,由于体积庞大、加工精度要求高,大型结构件的生产一直是企业面临的难题。详细分析了工程机械上大型结构件的结构特点,深入探讨了大型结构件的生产工艺性,并具体介绍了一种合理的生产工艺过程,对提高大型结构件的质量和生产效率具有重要意义。     

非协作通信中的3G ALE信号识别研究

3G ALE(Third Generation HF Automatic Link Establishment)通信由于其特有的抗截获和抗干扰性,受到了各国军方的广泛关注,同时也是非协作通信中的一个重要研究课题.为达到识别3G ALE信号的目的,本文首先分析了该信号的音响、载波、持续时间和带宽等基本特性,其次从3G A...     

Antifungal activity of ZnO nanoparticles--the role of ROS mediated cell injury

Metal oxide nanoparticles have marked antibacterial activity. The toxic effect of these nanoparticles, such as those comprised of ZnO, has been found to occur due to an interaction of the nanoparticle surface with water, and to increase with a decrease in particle size. In the present study, we tested the ability of ZnO nanoparticles to affect the viability of the pathogenic yeast, Candida albicans (C. albicans). A concentration-dependent effect of ZnO on the viability of C. albicans was observed. The minimal fungicidal concentration of ZnO was found to be 0.1 mg ml(-1) ZnO; this concentration caused an inhibition of over 95% in the growth of C. albicans. ZnO nanoparticles also inhibited the growth of C. albicans when it was added at the logarithmic phase of growth. Addition of histidine (a quencher of hydroxyl radicals and singlet oxygen) caused reduction in the effect of ZnO on C. albicans depending on its concentration. An almost complete elimination of the antimycotic effect was achieved following addition of 5 mM of histidine. Exciting the ZnO by visible light increased the yeast cell death. The effects of histidine suggest the involvement of reactive oxygen species, including hydroxyl radicals and singlet oxygen, in cell death. In light of the above results it appears that metal oxide nanoparticles may provide a novel family of fungicidal compounds.     

Highly directional emission and photon beaming from nanocrystal quantum dots embedded in metallic nanoslit arrays

We demonstrate a directional beaming of photons emitted from nanocrystal quantum dots that are embedded in a subwavelength metallic nanoslit array with a divergence angle of less than 4°. We show that the eigenmodes of the structure result in localized electromagnetic field enhancements at the Bragg cavity resonances, which could be controlled and engineered in both real and momentum space. The photon beaming is achieved using the enhanced resonant coupling of the quantum dots to these Bragg cavity modes, which dominates the emission properties of the quantum dots. We show that the emission probability of a quantum dot into the narrow angular mode is 20 times larger than the emission probability to all other modes. Engineering nanocrystal quantum dots with subwavelength metallic nanostructures is a promising way for a range of new types of active optical devices, where spatial control of the optical properties of nanoemitters is essential, on both the single and many photons level.