940 resultados para L71 - Mining, Extraction, and Refining:


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Established firms tend to pursue incremental innovation by modifying and refining their existing products and processes rather than developing radical innovations. In the face of resistance to change and incumbent inertia, which prevent the generation of novelty, established firms have turned towards corporate entrepreneurship as a means of exploiting knowledge accumulated within its own boundaries and exploring external markets. This paper focuses on one mode of corporate entrepreneurship, corporate incubation, informed by a study of a Technology Incubator at Philips. An account of the history of the incubator traces its progress from its inception in 2002-2006 when further incubators were formed, building on this experience and focusing on lifestyle and healthcare technologies. We identify ways in which the Philips incubator represents an alternative selection environment that effectively simulated the venture capitalist model of entrepreneurial innovation. © 2009 Blackwell Publishing Ltd.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Cognitive neuroscience defines the sense of agency as the experience of controlling one's own actions and, through this control, affecting the external world. We believe that the sense of personal agency is a key factor in how people experience interactions with technology. This paper draws on theoretical perspectives in cognitive neuroscience and describes two implicit methods through which personal agency can be empirically investigated. We report two experiments applying these methods to HCI problems. One shows that a new input modality - skin-based interaction - can substantially increase users' sense of agency. The second demonstrates that variations in the parameters of assistance techniques such as predictive mouse acceleration can have a significant impact on users' sense of agency. The methods presented provide designers with new ways of evaluating and refining empowering interaction techniques and interfaces, in which users experience an instinctive sense of control and ownership over their actions. Copyright 2012 ACM.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The operating range of an axial compressor is often restricted by a safety imposed stall margin. One possible way of regaining operating range is with the application of casing treatment. Of particular interest here is the type of casing treatment which extracts air from a high pressure location in the compressor and re-injects it through discrete loops into the rotor tip region. Existing re-circulation systems have the disadvantage of reducing compressor efficiency at design conditions because worked flow is unnecessarily re-circulated at these operating conditions. Re-circulation is really only needed near stall. This paper proposes a self-regulating casing treatment in which the re-circulated flow is minimized at compressor design conditions and maximized near stall. The self-regulating capability is achieved by taking advantage of changes which occur in the tip clearance velocity and pressure fields as the compressor is throttled toward stall. In the proof-of-concept work reported here, flow is extracted from the high pressure region over the rotor tips and re-injected just upstream of the same blade row. Parametric studies are reported in which the flow extraction and re-injection ports are optimized for location, shape and orientation. The optimized design is shown to compare favorably with a circumferential groove tested in the same compressor. The relationship between stall inception type and casing treatment effectiveness is also investigated. The self-regulating aspect of the new design works well: stall margin improvements from 2.2 to 6.0% are achieved for just 0.25% total air re-circulated near stall and half that near design conditions. The self-regulating capability is achieved by the selective location and orientation of the extraction hole; a simple model is discussed which predicts the optimum axial location. Copyright © 2011 by ASME.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Today's fast-paced, dynamic environments mean that for organizations to keep "ahead of the game", engineering managers need to maximize current opportunities and avoid repeating past mistakes. This article describes the development study of a collaborative strategic management tool - the Experience Scan to capture past experience and apply learning from this to present and future situations. Experience Scan workshops were held in a number of different technology organizations, developing and refining the tool until its format stabilized. From participants' feedback, the workshop-based tool was judged to be a useful and efficient mechanism for communication and knowledge management, contributing to organizational learning.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In this paper, we proposed a method of classification for viruses' complete genomes based on graph geometrical theory in order to viruses classification. Firstly, a model of triangular geometrical graph was put forward, and then constructed feature-space-samples-graphs for classes of viruses' complete genomes in feature space after feature extraction and normalization. Finally, we studied an algorithm for classification of viruses' complete genomes based on feature-space-samples-graphs. Compared with the BLAST algorithm, experiments prove its efficiency.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The coupling of surface plasmons to the photonic modes in hexagonal textured metallic microcavity was studied. The modified photonic modes enable efficient coupling with the luminescence source in the microcavity. Hexagonal photonic crystal lattice has higher folding symmetry providing more channels for surface plasmon coupling in different in-plane directions, i.e., more isotropic light extraction profile than one-or two-dimensional gratings. Results show that strong coupling between surface plasmon modes and the waveguide mode in the microcavity has led to angle-selective enhanced light extraction and it was as much as 12 times more light extracted compare to planar microcavity. (c) 2006 American Institute of Physics.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In recognition-based user interface, users’ satisfaction is determined not only by recognition accuracy but also by effort to correct recognition errors. In this paper, we introduce a crossmodal error correction technique, which allows users to correct errors of Chinese handwriting recognition by speech. The focus of the paper is a multimodal fusion algorithm supporting the crossmodal error correction. By fusing handwriting and speech recognition, the algorithm can correct errors in both character extraction and recognition of handwriting. The experimental result indicates that the algorithm is effective and efficient. Moreover, the evaluation also shows the correction technique can help users to correct errors in handwriting recognition more efficiently than the other two error correction techniques.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

需求变更是需求工程中不可避免的问题,会持续发生并贯穿于整个软件开发的生命周期中,并且会对项目的成本、进度、质量等多方面造成影响。需求度量工作是一个开发组织成长和进步的必要手段,也是对项目经验进行学习和总结最佳途径。只有做好了需求变更度量工作,才能逐渐了解需求变更的规律,这对于改善需求管理的质量,提高需求的可信度,都有着重要的作用。需求变更过程会导致大量的需求文档的版本产生,但是这些变更信息往往没有得到很好的记录,这使得需求度量工作变得很困难。 一般来讲,由于使用了配置管理工具,大的需求版本变更一般都可以直接从配置管理工具得到。但是很多小的变更仅仅反映在文档上,没有纳入配置管理或者没有填写变更信息,并且很多公司都仅仅使用word文档进行需求管理。一个项目会产生大量这种word文档,而变更的信息往往得不到很好的记录,这部分信息丢失了。一个项目的需求会发生很多次或大或小的变更,产生文档版本的数量是非常多的,这部分文档的变更信息如果完全采用人工阅读获取,工作量是非常巨大的,实施起来非常不实际。 本文采用文本相似度比较的方法,对word文档中的变更信息进行还原。识别文档的中需求的相似程度,然后根据设定的阈值来恢复出需求变更的增、删、改等信息。并且本文设计和实现了需求文档变更信息挖掘工具,采用工具恢复变更信息的方法相对手工查看,解决了手工查看费时费力的缺点,并且由于需求文档演化的逻辑连续性,大部分比较都是在相邻的变更版本之间,文档变化幅度不会特别大,准确性也可以得到较好的保证。本文最后采用了实际的项目文档数据对方法进行验证,验证了方法的有效性和准确度。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

随着国家发展对能源的迫切需求,石油作为我国能源的主要构成之一,其开采和冶炼也在不断地增加。然而由于某些相关管理环节的不完善引发的污染事故日趋增多,其中原油的土壤污染问题尤为严重。为研究原油在土壤中的入渗过程,通过室内土柱模拟实验,测定了原油在土壤中入渗的湿润距离、湿润推进速率与时间的关系以及被原油污染的土壤中残留物的含量。结果表明:对于同一质地土壤,随着容重的增加,原油在土壤中入渗的湿润距离、湿润推进速率和残留物的含量均降低;容重相同而质地不同的土壤,随着粉粒含量的增加,原油在土壤中入渗的湿润距离、湿润推进速率和残留物的含量均表现为降低趋势;原油在土壤中入渗的湿润距离随时间的变化可以用对数函数拟合,湿润推进速率与时间的关系可以用幂函数拟合,均达到显著水平。研究原油在土壤中的入渗对于了解原油在土壤中的迁移有着重要的意义。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

黄土高原沟壑区王东沟流域从1986年至2006年的土地利用/覆被发生了较大变化,土地利用动态指数分别为:耕地3.21%,园地-36.11%,林地-4.05%,牧草地4.24%,居民点及独立工矿用地-0.62%,交通运输用地-12.27%,未利用地1.85%;变化趋势是:耕地逐年向园地流转,园地变化烈度较大,其他各类用地变化不太显著。引起这一变化的主要因素是自然、社会、经济、技术以及政策因素。结合这一变化,针对黄土高原沟壑区的实际情况,在黄土高原沟壑区土地利用经营与管理方面,应重视土地产出效益与粮食安全的关系,在保障区域粮食安全的基础上实现效益最大化。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本文对1-辛基-3-甲基咪唑六氟磷酸盐离子液体([C8mim]PF6)在包头稀土矿分离钍以及攀西矿分离铈工艺中的应用作了初步探索。论文首先研究了伯胺N1923溶于离子液体对硫酸体系钍的萃取分离行为,考察了酸度、盐析剂浓度、萃取剂浓度等对N1923/IL萃取钍的影响,并与庚烷体系的萃取规律作了对比。在此基础上对萃取机理进行了探讨,提出了不同于分子溶剂体系的萃取机理,认为N1923/IL在水相有硫酸钠作为盐析剂时对钍的萃取为“胶束增溶”萃取机理。此外,钍对稀土的分离考察结果认为,虽然N1923/IL对钍的萃取效率降低,但在一定条件下钍对稀土仍能保持较高的分离系数。由此本文对N1923/IL应用于钍的分离实践作了初步评估。 论文的另外一部分工作研究了纯[C8mim]PF6及其与2-乙基己基膦酸二(2-乙基己基)酯(DEHEHP)的混合体系对硝酸铈(IV)的萃取性能。研究发现纯[C8mim]PF6本身对硝酸铈(IV)有良好的萃取选择性,机理考察结果认为铈(IV)的萃取是由于Ce4+离子在富硝酸根溶液中形成络阴离子Ce(NO3)62-并与离子液体的阴离子PF6—发生交换的结果。一种新型含铈离子液体[C8mim]2Ce(NO3)6的合成进一步证实了这一机理。反萃考察发现被萃入离子液相的铈(IV)用水可完全反萃,且萃取和反萃过程中因离子交换机理导致的离子液体流失可以通过添加适量离子液体组分的方法予以抑制。此外,本文考察了DEHEHP溶于[C8mim]PF6对于含氟硝酸体系铈(IV)的萃取行为,发现在一定条件下DEHEHP对铈(IV)的萃取能获得与分子溶剂中等同的萃取机理。在此基础上,采用DEHEHP/IL从氟碳铈矿分解液中进行分离铈和氟的研究,获得纯度为99.9%以上的纳米CeF3产品。由此我们提出一个将离子液体应用于攀西氟碳铈矿铈钍稀土分离流程的模型,为离子液体在稀土清洁分离流程中实现溶剂绿色化的目标提供了一个范例。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

该论文围绕金属元素的溶剂萃取和树脂吸附进行了一系列研究.考察了几种萃取剂的混合体系对稀土元素及过渡金属元素的萃取效应,同时,研究了酸性有机磷(瞬)类萃淋树脂对二价过渡金属元素的吸附性能,并讨论了它们用于分离金属元素的可能性.1.研究了盐酸和硝酸介质中β-二酮类萃取剂HPMBP与硫代中性有机磷(膦)类萃取剂Cyanex471X单独及混合体系对稀土元素La(Ⅲ)的萃取机理.2.研究了Cyanex272与伯胺N1923的混合物对Zn(Ⅱ)的协同萃取效应,得出了协萃反应方程式和平衡常数.3.考察了伯胺N1923与中性有机磷(膦)类萃取剂DEH/EHP的混合体系在盐酸介质中对Zn(Ⅱ)和Cd(Ⅱ)的萃取效应,研究了萃取机理,并研究了此混合体系对Zn(Ⅱ)和Cd(Ⅱ)的分离.4.揭示了Cyanex923萃取硝酸过程中出现第三相的机理和三相的相行为,讨论了第三相形成的影响因素.5.考察了盐酸介质中HEOPPA萃淋树脂对二价过渡金属元素的吸附平衡,得出了吸附反应方程式.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

建立了一种基于图像处理的快速瞳孔直径检测算法,运用此算法提取了反映阿片类药物成瘾人员与正常人对瞳孔光反射变化差异的3个特征值:绝对收缩幅度(absolute amplitude of contraction,AAC)、相对收缩幅度(relative amplitude of contraction,RAC)和收缩斜率(SCV,slope of contraction velocity);分别研究了成瘾、性别、近视、年龄、睡眠剥夺等因素对于这3个特征值的影响。不同性别、近视人员、睡眠剥夺人员与正常人之间的3个特征值均无显著差异,成瘾人员与之对比均显著减小。老年人相对于正常青年人,3个特征值都明显减小;与成瘾人员相比,仅在RAC值上有显著差异。结果表明,阿片类药物成瘾人员除了与正常人外,也与其他具有潜在影响瞳孔变化因素的非阿片成瘾人员在瞳孔对光反射的特征值上具有显著差异。该研究的实验数据为进一步建立基于检测瞳孔对光反射其直径发生变化的方法来快速、非接触地鉴别出阿片类药物成瘾人员提供了可靠的依据。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

综合运用环境地球化学、土壤学、生态学和统计学的方法开展了矿山废弃物尾矿石的堆置对土壤造成的污染以及矿区土壤重金属污染对白菜(Brassica Chinensis)的卫生品质和营养品质的影响研究。静态培养试验和动力学淋溶试验证明:在环境因素(如降水)的作用下,尾矿石的堆置将对下伏土壤的重金属含量产生长久影响,随着降水量以及酸度的增加,土壤中Cu、Cd、Pb、Zn的全量和有效态含量都有所升高并且土层间的差异减小。有机酸能不同程度地促进土壤中的重金属转化为有效态,增强重金属的生物有效性;多元梭酸比一元梭酸的转化率高。另外,有机酸对重金属的转化作用随其浓度的增大而增强,在低温范围内,随温度的升高而增加。通过网室盆栽试验,研究了土壤受Cu、Cd、Pb,Zn单一重金属污染后对大白菜吸收Cu、Cd、Pb、Zn以及植物体内粗纤维和维生素C含量的影响;同时还进一步对Cd-P交互作用影响大白菜吸收Cd、P以及植物体内粗纤维和维生素C含量的情况进行了研究,结果表明大白菜从污染的土壤吸收重金属与土壤中目标元素的含量呈极显著正相关,对非目标重金属的吸收情况复杂,因不同元素间的相互作用机制而异;白菜体内粗纤维和抗坏血酸含量随土壤重金属浓度的增加而降低,它们之间呈极显著的负相关关系。在采用大白菜进行高等植物毒性试验的基础上,首次运用典型相关分析方法对Cu、Cd、Pb、Zn复合污染土壤的生态毒性进行了评价,分别建立了由4元素共同组成的复合污染土壤毒性的线性组合函数和由芽生物量抑制率和根伸长抑制率组成的植物学表征的线性组合函数,并计算了其第一典型变量Toxl(土壤毒性)和BloL(植物学表征)之间的相关系数为0.94(p<0.01)。典型相关分析是介质毒性评价的有效方法之一。

Relevância:

100.00% 100.00%

Publicador: