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81.
Fuel injection rate shaping is a strategy to improve fuel efficiency and reduce harmful emissions in diesel engines. Due to their fast response, piezoelectric fuel injectors are capable of rate shaping operation. This paper describes a model-based closed-loop controller of injection flow rate for a piezoelectric fuel injector. This within-an-engine-cycle control strategy utilizes a dynamic surface control scheme and shows an injection flow rate tracking capability. Practical issues with LabVIEW FPGA control implementation are also addressed. The performance of the controller is verified with simulation and experimental results at different rail pressures and desired injection rates. The experiments show a maximum error of total fuel per one injection event of 2.5%. A stability analysis is also included. 相似文献
82.
多类别目标覆盖问题是目前无线传感器网络中的研究热点。针对现有目标覆盖算法在时间效率、网络生命周期等方面的不足,将多类别目标覆盖问题建模为基于线性规划的网络生命周期最大化问题,提出一种基于分簇的目标覆盖算法。该算法依据节点的剩余能量和感应能力,在每个簇结构内求解最优覆盖集的基础上得到接近于最优解的全局覆盖集,进而调度节点相应的感应模块去覆盖其感知范围内同属性的目标。实验结果表明,该算法是有效的,在网络生命周期和时间效率等方面均优于CWGC方案,接近于线性规划最优值。 相似文献
83.
基于糖尿病性视网膜病变中最早出现的微小动脉瘤病症进行了研究,提出一种有效的微小动脉瘤检测算法。首先在传统模板匹配算法的基础上提出了一种动态多参数模板匹配算法,并且使用相对误差和与相关系数来共同制约匹配度,从而实现了更为精确的匹配提取;其次提出了基于分布特性的计分策略和自适应加权的汇总策略,避免了单纯采用各个特征量作为独立约束指标进行筛选时忽视各个特征量的约束力大小的弊端。实验结果表明,该检测算法能够有效地提高微小动脉瘤的检测真阳性率。 相似文献
84.
J.A. DelgadoT.A. Nijhuis F. Kapteijn J.A. Moulijn 《Chemical engineering science》2002,57(11):1835-1847
A detailed transport model for the Multitrack setup, a TAP-like system, has been developed, which allows further analysis of adsorption, diffusion and catalysis phenomena. This includes the transport in the void part between the pulse valve and the reactor inlet. The effects of viscous flow and thermal transpiration, aspects that have not been studied in detail before for this type of setup, have been analyzed. A new expression for the modeling of the output signal is proposed depending on the positioning of the MS detector used in the study. The transport parameters of the model have been estimated by the analysis of the experimental pulse responses of the empty reactor system and the reactor charged with an inert packed bed. The proposed model reproduces the experimental pulse responses very well, and therefore can be extended to study systems with reacting or adsorbing beds by including the corresponding rate equations for the processes occurring in the bed of particles. 相似文献
85.
86.
在使用无底柱分段崩落法的矿山,大都存在着地压现象。其主要表现是采矿进路和联络道的变形破坏。对采矿进路在开挖和回采过程中各阶段受力情况的分析表明,进路的变形、破坏主要是受到岩体初始静应力、爆破动应力和矿柱支撑应力的综合作用的结果。 相似文献
87.
本文综合研究了螺带式搅拌器在假塑性液体中的混合特性及动力特性,测定了双螺带,内外螺带及螺带螺旋3种类型搅拌器的功率常数Kp和Metaner常数Ks,并得出混匀操作和传质工艺过程的放大准则。 相似文献
88.
Java作为计算机专业的核心专业课程,引入双语教学是发展的必然趋势.本文论述了开展双语教学的必要性,以及开展双语教学需要做的准备.在教学开展过程中,针对教材选择,教学实施和考核方式进行了论述. 相似文献
89.
《Journal of Visual Languages and Computing》2014,25(4):414-432
Context: The emergence of the long-tail in the market of software applications is shifting the role of end-users from mere consumers to becoming developers of applications addressing their unique, personal, and transient needs. On the Web, a popular form of such applications is called mashup, built out of the lightweight composition of Web APIs (reusable software components delivered as a service through the Web). To enable end-users to build mashups, there is a key problem that must be overcome: End-users lack programming knowledge as well as the interest to learn how to master the complex set of Web technologies required to develop mashups. End-User Development (EUD) is an emerging research field dealing with this type of problems. Its main goal is to design tools and techniques facilitating the development of software applications by non-programmers.Objective: The paper describes the design and evaluation of NaturalMash, an innovative EUD tool for mashups (a mashup tool). NaturalMash aims at enabling non-professional users without any knowledge of programming languages and skills to create feature-rich, interactive, and useful mashups.Methods: The design of NaturalMash adopts a formative evaluation approach, and has completed three design and evaluation iterations. The formative evaluations utilize usability testing, think aloud protocol, questionnaires, observation, and unstructured interviews. Additionally, we compare the expressive power of naturalmash with the state-of-the-art mashup tools.Results: The results from the formative evaluations helped us identify important usability problems. From an assessment point of view, the results were promising and sggested that the proposed tool has a short and gentle learning curve in a way that even non-programmers are able to rapidly build useful mashups. Also, the comparative evaluation results showed that NaturalMash offers a competitive level of expressive power compared with existing mashup tools targeting non-programmers.Conclusion: As the evaluation results indicate, NaturalMash provides a high level of expressive power while it is still highly usable by non-programmers. These suggest that we have successfully achieved the objective of the proposed tool, distinguishing it from existing mashup tools that are either too limited or highly specialized for non-professional users. 相似文献
90.
《Journal of Visual Languages and Computing》2014,25(4):481-493
Objective: We present a new non-photorealistic rendering method to render 3D scenes in the form of pencil-like sketches.Methods: This work is based on the observation that the dynamic feedback mechanism involving the human visual system and the motor control of the hand collectively generates the visual characteristics unique to hand-drawn sketches. At the heart of our approach is a trajectory planning and tracking algorithm that generate the sketch in multiple layers using a dynamic pen model. On each layer, a set of target strokes are generated from the silhouette lines, edges, and shaded regions which serve as the target trajectory for a closed-loop dynamic pen model. The pen model then produces the rendered sketch, whose characteristics can be adjusted with a set of trajectory and tracking parameters. This process continues in several layers until the tonal difference between the sketch and the original 3D render is minimized.Results: We demonstrate our approach with examples that are created by controlling the parameters of our sketch rendering algorithms.Conclusion: The examples not only show typical sketching artifacts that are common to human-drawn sketches but also demonstrate that it is capable of producing multiple sketching styles. 相似文献