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1.
This study presents packaged microscale liquid lenses actuated with liquid droplets of 300-700 μm in diameter using the dielectric force manipulation. The liquid microlens demonstrated function focal length tunability in a plastic package. The focal length of the liquid lens with a lens droplet of 500 μm in diameter is shortened from 4.4 to 2.2 mm when voltages applied change from 0 to 79 V(rms). Dynamic responses that are analyzed using 2000 frames∕s high speed motion cameras show that the advancing and receding times are measured to be 90 and 60 ms, respectively. The size effect of dielectric liquid microlens is characterized for a lens droplet of 300-700 μm in diameter in an aspect of focal length. 相似文献
2.
RUDENBERG R 《Journal of The Franklin Institute》1948,246(5):377-408
Increasing lens voltage, higher than the incident electron voltage, at first blocks the beam and then converts the electron lens into a curved mirror, the focal properties of which are analyzed.The embodiment of hyperbolic lenses is discussed by means of the boundary conditions which may be rigorously or approximately satisfied in actual designs. The effects of lateral apertures and windows on the imaging qualities of the field are considered in detail.Expressions are derived for velocity-, angular- and aperture-defects, the latter being merely a surface effect of the hyperbolic field. They all depend on a few parameters only of the lens field and are relatively small in magnitude. An experi- mental verification of the field structure with partial compensation of the defects shows favorable imaging qualities.Two-dimensional fields, constituting electron cylinder lenses, are considered in a similar way, leading to analogous formulations for the cardinal properties. 相似文献
3.
Hydrogels—natural or synthetic polymer networks that swell in water—can be made mechanically, chemically and electrically compatible with living tissues. There has been intense research and development of hydrogels for medical applications since the invention of hydrogel contact lenses in 1960. More recently, functional hydrogel coatings with controlled thickness and tough adhesion have been achieved on various substrates. Hydrogel-coated substrates combine the advantages of hydrogels, such as lubricity, biocompatibility and anti-biofouling properties, with the advantages of substrates, such as stiffness, toughness and strength. In this review, we focus on three aspects of functional hydrogel coatings: (i) applications and functions enabled by hydrogel coatings, (ii) methods of coating various substrates with different functional hydrogels with tough adhesion, and (iii) tests to evaluate the adhesion between functional hydrogel coatings and substrates. Conclusions and outlook are given at the end of this review. 相似文献
4.
国际河流水资源公平和合理利用的模式与新发展:实证分析、比较与借鉴 总被引：1，自引：0，他引：1
作为国际水资源法的基本原则,公平和合理利用原则在跨界水资源的分配和利用实践中得到了较广泛的运用。这种运用大致可以分为水量分配和合作开发两种模式,可分别称为公平和合理利用的“初级阶段”和“中级阶段”。受到可持续发展理念和国际环境法的影响,公平和合理利用原则也获得了新的发展。在这种新的发展形势下,基于国际河流流域的整体性,为使流域水资源开发利用获得最佳和可持续的效益,流域开发应贯彻全局思路,创立流域一体化管理模式。我国对境内国际河流的开发利用,应当循序渐进地开展一体化管理,流域水电开发应当进行环境和社会影响评价和后评价。我国作为上游国,如果因为需要维护河流流域的生态系统平衡而影响我国的开发利用,损失经济发展机会,应当积极寻求中下游国家给予生态补偿;同时关注下游国开发利用动态,积极维护我国与国际河流流域的整体利益。 相似文献
5.
对渐变折射率棒透镜和衍射光栅构成的单模光纤分波器的近轴分析,得到了分波方程.对确定的工作波长,根据分波方程选择渐变折射率棒透镜和衍射光栅参数,已制成了二波长和四波长分波器.实验与计算结果符合得很好.同理,也可以分析合波器. 相似文献
6.
Liu AQ 《Biomicrofluidics》2010,4(4):42901
This Special Topic section of Biomicrofluidics is on optofluidics or micro-optofluidic systems (MOFS), a burgeoning technology that aims to manipulate light and fluid at microscale and exploits their interaction to create highly versatile devices and integrated systems. This special issue puts together various contributed articles focusing on optofluidics or MOFS, which help inspire new research ideas and innovation in the microfluidics and nanofluidics community. 相似文献
7.
Communication is at the heart of knowledge transfer (KT). But studies of KT barriers do not explicitly consider the relationship and impact of specific communication modalities on KT. The modalities of computer-mediated communication (CMC), namely email, Voice Over Internet Protocol, Instant Messaging (IM) and the like are generally viewed as a group ‘CMC’. In this paper, we analyze the KT literature to distill 21 key barriers to successful KT. These barriers are then categorized according to basic communication theory. We then examine leading theories of CMC and discuss how based on these theories individual CMC modalities can be applied to KT barriers. We conclude with a model that presents the categorized KT barriers in a communication channel model that can be addressed by CMC modalities and that can potentially break down those barriers. 相似文献
8.
Proteins and glutathione (GSH) levels were estimated in the experimental groups. Levels of both proteins and glutathione in
the control and the treated groups were found to be significantly decreased compared to the normal group. The results show
that supplementation of riboflavin has beneficial effect by alleviating the oxidant injuries to GSH and proteins, which are
involved in the maintenance of transparency and protection of thiol groups of the lens. Thus, riboflavin has an active role
in the lens metabolism and has a potential to improve the metabolic activity of the cataractous lenses. 相似文献
9.
《Information processing & management》2022,59(2):102811
Open data is becoming ubiquitous as governments, companies, and even individuals have the option to offer more or less unrestricted access to their non-sensitive data. The benefits of open data, such as accessibility and transparency, have motivated and enabled a large number of research studies and applications in both academia and industry. However, each open data only offers a single perspective, and its potential inherent limitations (e.g., demographic biases) may lead to poor decisions and misjudgments. This paper discusses how to create and use multiple digital lenses empowered by open data, including census data (macro lens), search logs (meso lens), and social data (micro lens), to investigate general real-world events. To reveal the unique angles and perspectives brought by each open lens, we summarize and compare the underpinning open data from eleven dimensions, such as utility, data volume, dynamic variability, and demographic fairness. Then, we propose an easy-to-use and generalized open data driven framework, which automatically retrieves multi-source data, extracts features, and trains machine learning models for the event specified by answering what, when, and where questions. With low labor efforts, the framework’s generalization and automation capabilities guarantee an instant investigation of general events and phenomena, such as disasters, sports events, and political activities. We also conduct two case studies, i.e., the COVID-19 pandemic and Great American Eclipse (see Appendix), to demonstrate its feasibility and effectiveness at different time granularities. 相似文献
10.
A photometric method for the determination of camera exposures in motion picture work is described. The relation of exposure, object brightness and lens stop number is derived, and the proportionality constant empirically determined for “Pan Astro” lenses of two- and three-inch focal length. A nomographic chart of the exposure relation is given to simplify the determination of the lens stop number to be used for a given object brightness. 相似文献
11.
Y. J. Fan Y. C. Wu Y. Chen Y. C. Kung T. H. Wu K. W. Huang H. J. Sheen P. Y. Chiou 《Biomicrofluidics》2013,7(4)
We report a 3D microfluidic device with 32 detection channels and 64 sheath flow channels and embedded microball lens array for high throughput multicolor fluorescence detection. A throughput of 358 400 cells/s has been accomplished. This device is realized by utilizing solid immersion micro ball lens arrays for high sensitivity and parallel fluorescence detection. High refractive index micro ball lenses (n = 2.1) are embedded underneath PDMS channels close to cell detection zones in channels. This design permits patterning high N.A. micro ball lenses in a compact fashion for parallel fluorescence detection on a small footprint device. This device also utilizes 3D microfluidic fabrication to address fluid routing issues in two-dimensional parallel sheath focusing and allows simultaneous pumping of 32 sample channels and 64 sheath flow channels with only two inlets. 相似文献
12.
Cataract is one of the leading causes of visual disability often leading to blindness in the elderly population. One of the
causes is oxidation of proteins present in lens, by hydrogen peroxide (H2O2). In the present study 100 goat lenses were analyzed to determine the protective efficacy of ketoacids, against the oxidative
insult by H2O2. The ketoacids used were (pyruvate, alpha ketoglutarate and oxaloacetate), that are constantly produced endogenously. The
lenses were incubated as control and experimental groups in TC-199 media for 72 hrs. H2O2 concentration of 10mM was used to induce cataract. The biochemical parameters measured were levels of malondialdehyde (MDA),
a lipid peroxidation product and activity of glutathione peroxidase (G-Px), an enzymatic antioxidant. The results showed a
significant increase in the levels of MDA and significant decrease in the activity of G-Px in the cataractous lenses as compared
to control. After addition of ketoacids (pyruvate (10mM), alpha ketoglutarate (20mM) and oxaloacetate (20mM)) separately,
the levels of MDA decreased significantly and the activity of G-Px increased significantly. The results suggest that the ketoacids
can be very promising antioxidants for the treatment of cataract. They may also be useful in treating other disabilities related
to acute and chronic oxidative stress. 相似文献
13.
We apply a cognitive lens to understanding technology trajectories across the life cycle by developing a co-evolutionary model of technological frames and technology. Applying that model to each stage of the technology life cycle, we identify conditions under which a cognitive lens might change the expected technological outcome predicted by purely economic or organizational models. We also show that interactions of producers, users and institutions shape the development of collective frames around the meaning of new technologies. We thus deepen our understanding of sources of variation in the era of ferment, conditions under which a dominant design may be achieved, the underlying architecture of the era of incremental change and the dynamics associated with discontinuities. 相似文献
14.
Roberto R. Kampfner 《Information processing & management》1985,21(5):401-414
An organizational information system can be viewed, in a broad sense, as a computational model of organizational activity and function. Logical requirements of information systems are defined, according to this view, as constraints imposed by the logical structure of such a computational model on the design, implementation and operation of information systems. In this study a formal model for the specification of logical requirements is presented in detail and its role as a tool for systems development is discussed. Three main advantages of the specification of logical requirements that can be capitalized through the use of this formalism are: (1) logical requirements are invariant with respect to specific means in which information processing is actually accomplished; (2) they can be easily related to relevant aspects of organizational activity and function; and (3) they can be related to basic components of the corresponding software systems, either existing or being developed. 相似文献
15.
In this work, tuning rules of the PID controller have been developed by categorizing a system's response into distinct classes. The classes are formed using the shapes of the test oscillations induced by the system under the Modified Relay Feedback Test (MRFT) produced by specific system models. It is proposed that a physical system can be categorized into one of the proposed classes and thus the tuning rules for a particular class can apply to any kind of system from this class. The idea of producing tuning rules that are based on the shape of the oscillations induced in the loop containing the process comes from the observations that oscillatory responses of physical systems reveal just a few different shapes depending on system dynamics. For applying the developed optimal tuning rules for an arbitrary system, first, certain system characteristics are determined using a priori knowledge of the class model. Then the system's response with the application of the MRFT is examined to classify the oscillation waveform/shape. In this work, such classification is carried out using a cross-correlation algorithm. Finally, a class tuning rules are applied. 相似文献
16.
快速城市化背景下深圳土地利用时空变化的人文因素分析 总被引：3，自引：0，他引：3
本文以深圳为研究案例,在评述国内外相关研究的基础上,利用遥感土地利用数据、土地利用详查数据、政府部门资料和实地调查资料等多种数据源,应用定量分析和GIS空间分析技术从定性与定量的角度系统全面地开展了快速城市化背景下城市土地利用变化的人文因素研究。研究结果表明：应用因子分析方法可将影响深圳土地利用变化的因子可归纳为经济发展水平因子、城市化和工业化因子、人口因子和产业结构调整等四个因子;应用线性回归和指数回归等分析方法可将土地利用面积变化率和土地利用变化强度表达为影响因子的函数关系,从函数关系可知各影响因子对深圳土地利用变化的影响作用大小不同,人口、城市化与工业化因子的影响作用较大,经济发展水平和产业结构调整因子其次。 相似文献
17.
Information and communication technology is regarded as a critical means of addressing rural problems of information deficiency, ineffective communication and emotional disconnection. Most studies on information and communication technology for development (ICT4D) can be categorized as a top-down development approach and are often theoretical research or case studies conducted using qualitative methods. In this study, we discuss a new phenomenon of citizen-led information practices in rural areas driven by the rural community and its citizens. By employing a mixed-method approach combining case studies and social network analysis (SNA), we explore how ICT4D can be achieved through citizen-led information practices. This study makes theoretical contributions to the study of ICT4D and information practices as well as the mixed-method approach, which deepen our understanding of the citizen-led information practices of ICT4D. This study also provides practical suggestions to the governments, enterprises, social organizations and rural communities in ICT4D practices and ICT function design. 相似文献
18.
Assuring the quality control of publications in the scientific literature is one of the main challenges of the peer review process. Consequently, there has been an increasing demand for computing solutions that will help to maintain the quality of this process. Recently, the use of Artificial Intelligence techniques has been highlighted, applied in the detection of plagiarism, bias, among other functions. The assessment of the reviewer’s review has also been considered as important in the process, but, little is known about it, for instance, which techniques have been applied in this assessment or which criteria have been assessed. Therefore, this systematic literature review aims to find evidence regarding the computational approaches that have been used to evaluate reviewers' reports. In order to achieve this, five online databases were selected, from which 72 articles were identified that met the inclusion criteria of this review, all of which have been published since 2000. The result returned 10 relevant studies meeting the evaluation requirements of scientific article reviews. The review revealed that mechanisms to rank review reports according to a score, as well as the word analysis, are the most common tools, and that there is no consensus on quality criteria. The systematic literature review has shown that reviewers’ report assessment is a valid tool for maintaining quality throughout the process. However, it still needs to be further developed if it is to be used as a resource which surpass a single conference or journal, making the peer review process more rigorous and less based on random choice. 相似文献
19.
Consumers evaluate products through online reviews, in addition to sharing their product experiences. Online reviews affect product marketing, and companies use online reviews to investigate consumer attitudes and perceptions of their products. However, when analyzing a review, it is often the case that specific contexts are not taken into consideration and meaningful information is not obtained from the analysis results. This study suggests a methodology for analyzing reviews in the context of comparing two competing products. In addition, by analyzing the discriminative attributes of competing products, we were able to derive more specific information than an overall product analysis. Analyzing the discriminative attributes in the context of comparing competing products provides clarity on analyzing the strengths and weaknesses of competitive products and provides realistic information that can help the company's management activities. Considering this purpose, this study collected a review of the BB Cream product line in the cosmetics field. The analysis was sequentially carried out in three stages. First, we extracted words that represent discriminative attributes by analyzing the percentage difference of words. Second, different attribute words were classified according to the meaning used in the review by using latent semantic analysis. Finally, the polarity of discriminative attribute words was analyzed using Labeled-LDA. This analysis method can be used as a market research method as it can extract more information than a traditional survey or interview method, and can save cost and time through the automation of the program. 相似文献
20.
Madhur M. Goyal Devarshi U. Gajjar Dhara B. Patel Pradeep Sune Abhay R. Vasavda 《Indian journal of clinical biochemistry : IJCB》2009,24(4):375-380
Oxidative stress has been proposed as a common underlying mechanism of cataractogenesis. Experimental and observational data
suggest that micronutrients like vitamin C and vitamin E with antioxidant capabilities may retard the development of age-related
cataract. Effect of these factors on lens epithelium cells, center of lens metabolic activities, is not completely elucidated.
The aim of present study was to examine the effect of vitamin C and E on surgically removed lens epithelium cells of patients
with cataract. Capsulorhexis samples were collected from 170 patients, admitted for cataract surgery. Catalase specific activity
was estimated in lens epithelium cells with and without vitamin (C or E) treatment at different concentration for different
time duration. Student’s t-test was employed for data analysis. We observed that in ex-vivo condition, a) both vitamin C and
E bring about a decrease in catalase activity in lens epithelial cells. b) vitamin C showed toxic effect at high concentration.
c) 100μM was the optimum concentration at which both vitamins showed maximum antioxidant activity. It was concluded that both
vitamin C and E has direct effect on lens epithelium cells. At optimum concentration, they can reduce oxidative stress in
these cells thus can support to prevent or delay cataract development. 相似文献