WorldWideScience

Sample records for high aspheric departure

  1. High precision optical finishing of lightweight silicon carbide aspheric mirror

    Science.gov (United States)

    Kong, John; Young, Kevin

    2010-10-01

    Critical to the deployment of large surveillance optics into the space environment is the generation of high quality optics. Traditionally, aluminum, glass and beryllium have been used; however, silicon carbide becomes of increasing interest and availability due to its high strength. With the hardness of silicon carbide being similar to diamond, traditional polishing methods suffer from slow material removal rates, difficulty in achieving the desired figure and inherent risk of causing catastrophic damage to the lightweight structure. Rather than increasing structural capacity and mass of the substrate, our proprietary sub-aperture aspheric surface forming technology offers higher material removal rates (comparable to that of Zerodur or Fused Silica), a deterministic approach to achieving the desired figure while minimizing contact area and the resulting load on the optical structure. The technology performed on computer-controlled machines with motion control software providing precise and quick convergence of surface figure, as demonstrated by optically finishing lightweight silicon carbide aspheres. At the same time, it also offers the advantage of ideal pitch finish of low surface micro-roughness and low mid-spatial frequency error. This method provides a solution applicable to all common silicon carbide substrate materials, including substrates with CVD silicon carbide cladding, offered by major silicon carbide material suppliers. This paper discusses a demonstration mirror we polished using this novel technology. The mirror is a lightweight silicon carbide substrate with CVD silicon carbide cladding. It is a convex hyperbolic secondary mirror with 104mm diameter and approximately 20 microns aspheric departure from best-fit sphere. The mirror has been finished with surface irregularity of better than 1/50 wave RMS @632.8 nm and surface micro-roughness of under 2 angstroms RMS. The technology has the potential to be scaled up for manufacturing capabilities of

  2. Fabrication of Aspheric Micro-Lens Mold with High Aspect Ratio

    Science.gov (United States)

    Naniwa, Irizo; Kanamaru, Masatoshi; Nakamura, Shigeo; Shimano, Takeshi; Horino, Masaya

    The optical pickup of our Small-Form-Factor Optical Disc Drives (SFFODDs) requires a micro-objective whose profile is composed of two aspheric surfaces. However, it is difficult to fabricate a micro-objective with an arbitrary aspheric surface and high aspect ratio using conventional techniques. We propose here a new method to fabricate an aspheric micro-lens mold with high aspect ratio. This method uses the micro-loading effect in Deep Reactive Ion Etching (DRIE) and isotropic Reactive Ion Etching (RIE). The micro-loading effect is a phenomenon that leads to different etching depths depending on the aperture size of the mask layer used in etching. We fabricated an aspheric micro-lens mold for the prototype by using the proposed method after experimental evaluations of the micro-loading effect for a feasibility study. The profile of the first prototype was slightly different from the designed one according as the distance from the lens center increase. The profile error of the second prototype was reduced by using a mask that had multiple apertures with the smallest aperture located outside the area where the crater was formed. Our proposed method was found to be effective for fabricating a micro-lens mold with an arbitrary aspheric surface and high aspect ratio.

  3. High-efficiency fabrication of aspheric microlens arrays by holographic femtosecond laser-induced photopolymerization

    Science.gov (United States)

    Hu, Yanlei; Chen, Yuhang; Ma, Jianqiang; Li, Jiawen; Huang, Wenhao; Chu, Jiaru

    2013-09-01

    Manufacture of aspheric microlens has always been technically challenging for conventional approaches due to their complex curved profile and tiny sizes. Two-photon polymerization is capable of producing arbitrary shape with high spatial resolution, apart from the disadvantage of ultra-low rate of yield resulting from point-by-point writing strategy. Here, we report parallel fabrication of aspheric microlens arrays (AMLAs) by taking advantage of holographic femtosecond laser direct-writing. The inherent constraints of the spatial light modulator are taken into consideration for achieving improved intensity uniformity and enhanced diffraction efficiency. Closely-packed AMLAs with designable optical parameters are readily fabricated with excellent optical performance.

  4. Asphere, O asphere, how shall we describe thee?

    Science.gov (United States)

    Forbes, G. W.; Brophy, C. P.

    2008-09-01

    Two key criteria govern the characterization of nominal shapes for aspheric optical surfaces. An efficient representation describes the spectrum of relevant shapes to the required accuracy by using the fewest decimal digits in the associated coefficients. Also, a representation is more effective if it can, in some way, facilitate other processes - such as optical design, tolerancing, or direct human interpretation. With the development of better tools for their design, metrology, and fabrication, aspheric optics are becoming ever more pervasive. As part of this trend, aspheric departures of up to a thousand microns or more must be characterized at almost nanometre precision. For all but the simplest of shapes, this is not as easy as it might sound. Efficiency is therefore increasingly important. Further, metrology tools continue to be one of the weaker links in the cost-effective production of aspheric optics. Interferometry particularly struggles to deal with steep slopes in aspheric departure. Such observations motivated the ideas described in what follows for modifying the conventional description of rotationally symmetric aspheres to use orthogonal bases that boost efficiency. The new representations can facilitate surface tolerancing as well as the design of aspheres with cost-effective metrology options. These ideas enable the description of aspheric shapes in terms of decompositions that not only deliver improved efficiency and effectiveness, but that are also shown to admit direct interpretations. While it's neither poetry nor a cure-all, an old blight can be relieved.

  5. Variable aberration generator using a high-order even aspheric singlet for testing optical surfaces

    Science.gov (United States)

    Lu, Jinfeng; Chen, Shanyong; Xue, Shuai

    2016-10-01

    Traditional null optics is generally designed for a particular optical surface. It must be redesigned when the test surface is changed no matter the null optic is reflective, transmitted or a CGH. Development of advanced optical machining and testing based on deterministic figuring and null test makes it possible to apply high-order aspheres. This paper presents a plano-concave singlet to realize variable aberration correction for testing different surfaces. The concave surface is an even asphere with high-order terms. By changing the axial distances among the transmission sphere, the null singlet and the test surface, variable aberrations are generated to meet the aberration balance requirement for various surfaces. The residual aberrations are confirmed within the vertical dynamic range of measurement of the interferometer. It enables flexible testing of optical surfaces without dedicated null optics. The optical design verifies that the aspheric singlet can be used to test conic surfaces with different conic constant and radius of curvature ranging from ellipsoid, paraboloid to hyperboloid and an even asphere.

  6. Application of Q-type aspheric surface in the design of Wynne-Dyson projection lens

    Science.gov (United States)

    Ho, Cheng-Fang; Peng, Wei-Jei; Hsu, Wei-Yao

    2016-10-01

    ITRC dedicates in high precision optics for more than 40 years and focuses in lithography optics for projection system recently. The first project of the lithography optics in ITRC is an i-line Wynne-Dyson projection lens for 3D-ICs applications. The Wynne-Dyson projection lens is a classical design for unity magnification projection system. We take the advantages of the established benefits of Wynne-Dyson lens and modify it. ITRC`s Wynne-Dyson lens is a 0.16 NA system with unity magnification, which is designed in double telecentricity and long working distance. The projection lens comprises three lenses and one concave mirror. Two aspheric surfaces are deployed in lens 1 and concave mirror. A lens with aspheric surfaces can correct for aberration and deliver a higher performance with fewer lens elements; therefore it has advantages of compact and light. However, aspheres are more difficult to fabricate and higher cost than spherical surface. In order to control the testability and manufacturability of the aspheric surface, the Q-type aspheric surfaces are applied in our design phase and manufacture process. We optimize for both performance and manufacturability by Q-type aspheric surfaces. Not only a testable and manufacturable asphere can be approached but also an additional benefits of less sensitive and cost-effective to manufacture to the required specification. In this paper, the Q-type aspheric surfaces and slope constraint are applied to a Wynne-Dyson projection lens, the testability of Q-type aspheric surfaces by the departure from best-fit-sphere and fringe density of interferometry are estimated. Furthermore, subaperture stitching interferometer system (ASI, from QED technologies) is also applied for testability comparison. The tolerance and sensitivity are also discussed. Finally, the results show a diffraction limit approached lens with testable aspheric surface is designed using Q-type aspheric surface. One of the asphere is 150 m departure from best

  7. Wide-aperture aspherical lens for high-resolution terahertz imaging

    Science.gov (United States)

    Chernomyrdin, Nikita V.; Frolov, Maxim E.; Lebedev, Sergey P.; Reshetov, Igor V.; Spektor, Igor E.; Tolstoguzov, Viktor L.; Karasik, Valeriy E.; Khorokhorov, Alexei M.; Koshelev, Kirill I.; Schadko, Aleksander O.; Yurchenko, Stanislav O.; Zaytsev, Kirill I.

    2017-01-01

    In this paper, we introduce wide-aperture aspherical lens for high-resolution terahertz (THz) imaging. The lens has been designed and analyzed by numerical methods of geometrical optics and electrodynamics. It has been made of high-density polyethylene by shaping at computer-controlled lathe and characterized using a continuous-wave THz imaging setup based on a backward-wave oscillator and Golay detector. The concept of image contrast has been implemented to estimate image quality. According to the experimental data, the lens allows resolving two points spaced at 0.95λ distance with a contrast of 15%. To highlight high resolution in the THz images, the wide-aperture lens has been employed for studying printed electronic circuit board containing sub-wavelength-scale elements. The observed results justify the high efficiency of the proposed lens design.

  8. Non-contact metrology of aspheric surfaces based on MWLI technology

    Science.gov (United States)

    Berger, G.; Petter, J.

    2013-09-01

    A non-contact optical scanning metrology solution measuring aspheric surfaces is presented, which is based on multi wavelength interferometry (MWLI). The technology yields high density 3D data in short measurement times (including set up time) and provides high, reproducible form measurement accuracy. It measures any asphere without restrictions in terms of spherical departures. In addition, measurement of a large variety of special optics is enabled, such as annular lenses, segmented optics, optics with diffractive steps, ground optics, optics made of opaque and transparent materials, and small and thin optics (e.g. smart phone lenses). The measurement instrument can be used under production conditions.

  9. Research on controlling middle spatial frequency error of high gradient precise aspheric by pitch tool

    Science.gov (United States)

    Wang, Jia; Hou, Xi; Wan, Yongjian; Shi, Chunyan; Zhong, Xianyun

    2016-09-01

    Extreme optical fabrication projects known as EUV and X-ray optic systems, which are representative of today's advanced optical manufacturing technology level, have special requirements for the optical surface quality. In synchroton radiation (SR) beamlines, mirrors of high shape accuracy is always used in grazing incidence. In nanolithograph systems, middle spatial frequency errors always lead to small-angle scattering or flare that reduces the contrast of the image. The slope error is defined for a given horizontal length, the increase or decrease in form error at the end point relative to the starting point is measured. The quality of reflective optical elements can be described by their deviation from ideal shape at different spatial frequencies. Usually one distinguishes between the figure error, the low spatial error part ranging from aperture length to 1mm frequencies, and the mid-high spatial error part from 1mm to 1 μm and from1 μm to some 10 nm spatial frequencies, respectively. Firstly, this paper will disscuss the relationship between slope error and middle spatial frequency error, which both describe the optical surface error along with the form profile. Then, experimental researches will be conducted on a high gradient precise aspheric with pitch tool, which aim to restraining the middle spatial frequency error.

  10. Manufacturing progress of production of high aspherical axis and off-axis astronomical and space optics for the last decade

    Science.gov (United States)

    Semenov, Aleksandr P.; Abdulkadyrov, Magomed A.; Belousov, Sergey P.; Ignatov, Aleksandr N.; Patrikeev, Vladimir E.

    2016-10-01

    The article describes the technology of production of astronomical and space mirrors from Astrositall CO-115M including its properties and stability of these properties over time and presents the results of material long-term testing. The article also describes computer-controlled methods of large-scaled optics production and testing, including high aspherical, off-axis and thin mirrors, using the examples of production of mirrors at JSC LZOS.

  11. High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric,aberration correcting monofocal intraocular lens

    Institute of Scientific and Technical Information of China (English)

    Florian; T; A; Kretz; Tamer; Tandogan; Ramin; Khoramnia; Gerd; U; Auffarth

    2015-01-01

    ·AIM: To evaluate the quality of vision in respect to high order aberrations and straylight perception after implantation of an aspheric, aberration correcting,monofocal intraocular lens(IOL).·METHODS: Twenty-one patients(34 eyes) aged 50 to83 y underwent cataract surgery with implantation of an aspheric, aberration correcting IOL(Tecnis ZCB00,Abbott Medical Optics). Three months after surgery they were examined for uncorrected(UDVA) and corrected distance visual acuity(CDVA), contrast sensitivity(CS)under photopic and mesopic conditions with and without glare source, ocular high order aberrations(HOA, Zywave II) and retinal straylight(C-Quant).· RESULTS: Postoperatively, patients achieved a postoperative CDVA of 0.0 log MAR or better in 97.1% of eyes. Mean values of high order abberations were +0.02±0.27(primary coma components) and-0.04 ±0.16(spherical aberration term). Straylight values of the C-Quant were 1.35±0.44 log which is within normal range of age matched phakic patients. The CS measurements under mesopic and photopic conditions in combination with and without glare did not show any statistical significance in the patient group observed(P ≥0.28).· CONCLUSION: The implantation of an aspherical aberration correcting monofocal IOL after cataractsurgery resulted in very low residual higher order aberration(HOA) and normal straylight.

  12. Fast optical 3D form measurement of aspheres including determination of thickness and wedge and decenter errors

    Science.gov (United States)

    Stover, E.; Berger, G.; Wendel, M.; Petter, J.

    2015-10-01

    A method for non-contact 3D form testing of aspheric surfaces including determination of decenter and wedge errors and lens thickness is presented. The principle is based on the absolute measurement capability of multi-wavelength interferometry (MWLI). The approach produces high density 3D shape information and geometric parameters at high accuracy in short measurement times. The system allows inspection of aspheres without restrictions in terms of spherical departures, of segmented and discontinuous optics. The optics can be polished or ground and made of opaque or transparent materials.

  13. Aspherical supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Kasen, Daniel Nathan [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    Although we know that many supernovae are aspherical, the exact nature of their geometry is undetermined. Because all the supernovae we observe are too distant to be resolved, the ejecta structure can't be directly imaged, and asymmetry must be inferred from signatures in the spectral features and polarization of the supernova light. The empirical interpretation of this data, however, is rather limited--to learn more about the detailed supernova geometry, theoretical modeling must been undertaken. One expects the geometry to be closely tied to the explosion mechanism and the progenitor star system, both of which are still under debate. Studying the 3-dimensional structure of supernovae should therefore provide new break throughs in our understanding. The goal of this thesis is to advance new techniques for calculating radiative transfer in 3-dimensional expanding atmospheres, and use them to study the flux and polarization signatures of aspherical supernovae. We develop a 3-D Monte Carlo transfer code and use it to directly fit recent spectropolarimetric observations, as well as calculate the observable properties of detailed multi-dimensional hydrodynamical explosion simulations. While previous theoretical efforts have been restricted to ellipsoidal models, we study several more complicated configurations that are tied to specific physical scenarios. We explore clumpy and toroidal geometries in fitting the spectropolarimetry of the Type Ia supernova SN 2001el. We then calculate the observable consequences of a supernova that has been rendered asymmetric by crashing into a nearby companion star. Finally, we fit the spectrum of a peculiar and extraordinarily luminous Type Ic supernova. The results are brought to bear on three broader astrophysical questions: (1) What are the progenitors and the explosion processes of Type Ia supernovae? (2) What effect does asymmetry have on the observational diversity of Type Ia supernovae, and hence their use in cosmology? (3

  14. Aspherical supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Kasen, Daniel Nathan

    2004-05-21

    Although we know that many supernovae are aspherical, the exact nature of their geometry is undetermined. Because all the supernovae we observe are too distant to be resolved, the ejecta structure can't be directly imaged, and asymmetry must be inferred from signatures in the spectral features and polarization of the supernova light. The empirical interpretation of this data, however, is rather limited--to learn more about the detailed supernova geometry, theoretical modeling must been undertaken. One expects the geometry to be closely tied to the explosion mechanism and the progenitor star system, both of which are still under debate. Studying the 3-dimensional structure of supernovae should therefore provide new break throughs in our understanding. The goal of this thesis is to advance new techniques for calculating radiative transfer in 3-dimensional expanding atmospheres, and use them to study the flux and polarization signatures of aspherical supernovae. We develop a 3-D Monte Carlo transfer code and use it to directly fit recent spectropolarimetric observations, as well as calculate the observable properties of detailed multi-dimensional hydrodynamical explosion simulations. While previous theoretical efforts have been restricted to ellipsoidal models, we study several more complicated configurations that are tied to specific physical scenarios. We explore clumpy and toroidal geometries in fitting the spectropolarimetry of the Type Ia supernova SN 2001el. We then calculate the observable consequences of a supernova that has been rendered asymmetric by crashing into a nearby companion star. Finally, we fit the spectrum of a peculiar and extraordinarily luminous Type Ic supernova. The results are brought to bear on three broader astrophysical questions: (1) What are the progenitors and the explosion processes of Type Ia supernovae? (2) What effect does asymmetry have on the observational diversity of Type Ia supernovae, and hence their use in cosmology? (3

  15. Solutions on a high-speed wide-angle zoom lens with aspheric surfaces

    Science.gov (United States)

    Yamanashi, Takanori

    2012-10-01

    Recent development in CMOS and digital camera technology has accelerated the business and market share of digital cinematography. In terms of optical design, this technology has increased the need to carefully consider pixel pitch and characteristics of the imager. When the field angle at the wide end, zoom ratio, and F-number are specified, choosing an appropriate zoom lens type is crucial. In addition, appropriate power distributions and lens configurations are required. At points near the wide end of a zoom lens, it is known that an aspheric surface is an effective means to correct off-axis aberrations. On the other hand, optical designers have to focus on manufacturability of aspheric surfaces and perform required analysis with respect to the surface shape. Centration errors aside, it is also important to know the sensitivity to aspheric shape errors and their effect on image quality. In this paper, wide angle cine zoom lens design examples are introduced and their main characteristics are described. Moreover, technical challenges are pointed out and solutions are proposed.

  16. [Aspheric optics: physical fundamentals].

    Science.gov (United States)

    Mrochen, M; Büeler, M

    2008-03-01

    Especially regarding intraocular lenses and refractive corneal surgery, one finds numerous concepts on how to improve the optical quality of the human eye through aspheric optics. Aspheric optics consists of optical surfaces in which at least one surface (for example, the corneal surface) deviates from the spherical shape. An aspheric (that is, not spherical) surface enables the correction of aberrations, especially the spherical aberration, by freely shaping the optical surface. The optical aberrations of the human eye can theoretically be minimized through the use of aspheric optics; however, the results are always affected by the optical properties of the cornea and the lens. Aspheric intraocular lenses allow a reduction of postoperative spherical aberrations of the patient's eye, but an optimal individualized conformation can result only when the shape of the cornea (asphericity) is considered. By the same token, the ideal corneal asphericity after refractive surgery for an individual eye cannot be defined without knowing the optical properties of the intraocular structure. Theoretical observations of aspheric optics in refractive surgery show that with aspheric approaches, a higher optical quality for the human eye can be attained. These theoretical advantages must, however, prove themselves in everyday clinical routine.

  17. Nanometer profile measurement of large aspheric optical surface by scanning deflectometry with rotatable devices

    Science.gov (United States)

    Xiao, Muzheng; Jujo, Satomi; Takahashi, Satoru; Takamasu, Kiyoshi

    2011-09-01

    Large aspheric optical mirrors and lens are wildly used in high-tech industry such as huge telescopes and synchrotron radiation facilities. The measurement uncertainty of the surfaces is needed to be under several tens of nanometers. Current methods such as interferometry method are not available for measuring aspheric surface with departure over hundreds of wavelength. In this paper, we proposed a new method called improved 3D deflectometry method. Rotatable optical devices are applied to enlarge the measuring range of autocollimator with highly accuracy but small measuring range. Data processing methods are also proposed to improve the measurement uncertainty. Experimental setup is designed based on proposed method. Spherical concave mirror with curvature radius of 5000 mm is measured successfully. The repeatability (mean standard deviation) of 10 times measurement is less than 10 nanometers.

  18. Asphericity in supernova explosions from late-time spectroscopy.

    Science.gov (United States)

    Maeda, Keiichi; Kawabata, Koji; Mazzali, Paolo A; Tanaka, Masaomi; Valenti, Stefano; Nomoto, Ken'ichi; Hattori, Takashi; Deng, Jinsong; Pian, Elena; Taubenberger, Stefan; Iye, Masanori; Matheson, Thomas; Filippenko, Alexei V; Aoki, Kentaro; Kosugi, George; Ohyama, Youichi; Sasaki, Toshiyuki; Takata, Tadafumi

    2008-02-29

    Core-collapse supernovae (CC-SNe) are the explosions that announce the death of massive stars. Some CC-SNe are linked to long-duration gamma-ray bursts (GRBs) and are highly aspherical. One important question is to what extent asphericity is common to all CC-SNe. Here we present late-time spectra for a number of CC-SNe from stripped-envelope stars and use them to explore any asphericity generated in the inner part of the exploding star, near the site of collapse. A range of oxygen emission-line profiles is observed, including a high incidence of double-peaked profiles, a distinct signature of an aspherical explosion. Our results suggest that all CC-SNe from stripped-envelope stars are aspherical explosions and that SNe accompanied by GRBs exhibit the highest degree of asphericity.

  19. Influence of soft bonding layer material viscoplasticity on thermal lens and aspherical aberration of high-power thin disk laser

    Science.gov (United States)

    Wang, Mu; Zhu, Guangzhi; Zhu, Xiao; Feng, Yufan; Gao, Jiapeng

    2016-11-01

    An numerical model considering solder viscoplasticity is developed to analyze the thermal deformation of laser disk with indium bonded. The characteristic of soft bonding material is described using Anand viscoplasticity model. The Finite Element Method analytical results show that the back surface of laser disk with pumping will deform more significantly with time and finally be steady. Correspondingly the refraction power increase gradually and diffraction loss induced by aspherical aberration decrease gradually. Futhermore when pump spot is larger the refraction power and aspherical aberration will change more due to solder viscoplasticity.

  20. High-Efficiency Ultra-Precision Turning for Complex Aspheric Mirrors%复杂非球面镜高效超精密车削加工法

    Institute of Scientific and Technical Information of China (English)

    张效栋; 房丰洲; 程颖; 魏桂爽

    2010-01-01

    This paper introduced the categories of complex aspheric mirrors to study the fabrication of this complex surface using ultra-precision diamond turning.The machining method and cutting path optimal design were proposed in detail.In experiments,one rotationally symmetric complex aspheric mirror was machined.After cutting,each segment of aspheric was measured using the ultra-precision measuring method,with the results used to compensate the cutting to achieve the ultimate surface roughness Ra of5.14 nm and a form error P-V within 200 nm.Besides,another non-rotationally symmetric aspheric array was also machined experimentally with the cutting path designed by the proposed method.The cutting parameters were computed according to the surface form for machining and the finished surface roughness Ra achieved was 7.81 nm.The experimental results prove that the proposed high-efficiency machining method can meet most requirements of complex aspheric.%本文中对复杂面形的非球面镜进行了分类,并从加工方法和加工路径优化设计等方面研究了复杂非球面镜的超精密车削方法.对回转对称的复杂非球面镜进行了加工实验,并借助超精密测量技术对各段曲面进行面形测量,依据测量结果实现面形补偿加工.最终粗糙度Ra达5.14 nm,形状精度P-V值达200 nm.采用提出的方法对非回转对称的非球面阵列进行加工路径设计,根据具体面形进行加工参数选择和实际加工,得到粗糙度R.为7.81nm的表面.实验结果证明了提出的加工方法高效实用,可以满足大部分复杂非球面的应用需求.

  1. Research on CNC Turning System of Aspheric Machining Grinding Wheel

    Institute of Scientific and Technical Information of China (English)

    ZOU Qin; GUO Yin-biao

    2005-01-01

    The technology of machining aspheric surface with high precision is the premise for the application of aspheric surface. The grinding machining with error compensation is a commonly used method to machine aspheric surface, which will directly influence the quality of aspheric workpiece surface. Multifunctional CNC grinding wheel truing system is a four-axis CNC truing system which can be applied to grinding wheel truing. In this system,DSP-based multi-axes motion control card is adopted as the controller, and visual C++ is used as development tool.When the design of hardware and software is completed, the system can implement truing of various grinding wheel with high precision aspheric machining such as plane grinding wheel, arc grinding one, and sphere grinding one.

  2. Convex Aspherical Surface Testing Using Catadioptric Partial Compensating System

    Science.gov (United States)

    Wang, Jingxian; Hao, Qun; Hu, Yao; Wang, Shaopu; Li, Tengfei; Tian, Yuhan; Li, Lin

    2016-01-01

    Aspheric optical components are the indispensable part of modern optics systems. With the constant development of aspheric optical fabrication technique, the systems with large aperture convex aspheric optical components are widely used in astronomy and space optics. Thus, the measurement of the figure error of the whole convex aspherical surface with high precision comes to be a challenge in the area of optical surface manufacture, and surface testing method is also very important. This paper presents a new partial compensating system by the combination of a refractive lens and a reflective mirror for testing convex aspherical surface. The refractive lens is used to compensate the aberration of the tested convex asphere partially. The reflective mirror is a spherical mirror which is coaxial to the refractive lens and reflecting the lights reflected by the tested convex asphere back to the convex asphere itself. With the long focal length and large aperture system we can realize a lighter and more compact system than the refractive partial compensating system because the spheric reflective mirror is more easily to realize and can bending the light conveniently.

  3. Departure of high temperature iron lines from the equilibrium state in flaring solar plasmas

    CERN Document Server

    Kawate, Tomoko; Jess, David B

    2016-01-01

    The aim of this study is to clarify if the assumption of ionization equilibrium and a Maxwellian electron energy distribution is valid in flaring solar plasmas. We analyze the 2014 December 20 X1.8 flare, in which the \\ion{Fe}{xxi} 187~\\AA, \\ion{Fe}{xxii} 253~\\AA, \\ion{Fe}{xxiii} 263~\\AA\\ and \\ion{Fe}{xxiv} 255~\\AA\\ emission lines were simultaneously observed by the EUV Imaging Spectrometer onboard the Hinode satellite. Intensity ratios among these high temperature Fe lines are compared and departures from isothermal conditions and ionization equilibrium examined. Temperatures derived from intensity ratios involving these four lines show significant discrepancies at the flare footpoints in the impulsive phase, and at the looptop in the gradual phase. Among these, the temperature derived from the \\ion{Fe}{xxii}/\\ion{Fe}{xxiv} intensity ratio is the lowest, which cannot be explained if we assume a Maxwellian electron distribution and ionization equilibrium, even in the case of a multi-thermal structure. This re...

  4. Matter mixing in aspherical core-collapse supernovae: a search for possible conditions for conveying $^{56}$Ni into high velocity regions

    CERN Document Server

    Ono, Masaomi; Ito, Hirotaka; Lee, Shiu-Hang; Mao, Jirong; Hashimoto, Masa-aki; Tolstov, Alexey

    2013-01-01

    We perform two-dimensional axisymmetric hydrodynamic simulations of matter mixing in aspherical core-collapse supernova explosions of a 16.3 $M_{\\odot}$ star with a compact hydrogen envelope. Observations of SN 1987A have provided evidence that $^{56}$Ni synthesized by explosive nucleosynthesis is mixed into fast moving matter ($\\gtrsim$ 3,500 km s$^{-1}$) in the exploding star. In order to clarify the key conditions for reproducing such high velocity of $^{56}$Ni, we revisit matter mixing in aspherical core-collapse supernova explosions. Explosions are initiated artificially by injecting thermal and kinetic energies around the interface between the iron core and the silicon-rich layer. Perturbations of 5% or 30% amplitude in the radial velocities are introduced at several points in time. We found that no high velocity $^{56}$Ni can be obtained if we consider bipolar explosions with perturbations (5% amplitude) of pre-supernova origins. If large perturbations (30% amplitude) are introduced or exist due to som...

  5. The research of the modern aspheric manufacturing technology

    Science.gov (United States)

    Jian, Geng; Hui, Changshun; Zhang, Jian

    2002-09-01

    Aspheric optical elements have been applied in many kinds of advanced optical systems especially in military and space optic fields accompanied by the development of the optic science. Ultra-precision aspheric surface can improve the optical performance effectively. It also can reduce the dimensions and the weights of the systems, which is the major advantage of it. In order to achieve the high-precision aspheric surfaces, some methods of the aspheric fabrication and metrology have been generated such as the diamond turning, molding, holography and some other special polishing manners based on the traditional craft production and measurement. In this article we described the manufacturing methods of aspheric element in brief and then we posed one way of the production about the aspheric surface. We introduce not only the manufacturing machine and measuring instrument about this kind of element but also the optical and mechanical parameters about the grinding and polishing, as well as technology of the process control. All devices compose a cycle of the production that is flexible and convenient to generate aspheric elements. It attribute to the high-speed production and improvement of efficiency in the factory.

  6. Lo calized high pressure near an aspheric encapsulated microbubble%非球形包膜微泡近场局部高压研究

    Institute of Scientific and Technical Information of China (English)

    邵纬航; 陈伟中

    2014-01-01

    Based on hydrodynamics, the pressure of the liquid outside an aspheric encapsulated bubble driven by ultrasound is studied, and its analytical expression is derived. Numerical simulation shows that 1) the aspheric shape of an encapsulated bubble makes little influence on the pressure of the liquid far away from the bubble;2) the pressure is extremely high at some local places of the liquid near an aspheric encapsulated bubble, and the pressure values at these places are apparently larger than those for a spherical encapsulated bubble at the same conditions. This phenomenon is of significance in the applications such as high intensity ultrasound therapy, drug delivery, cell membrane perforation, etc. As the ultrasound frequency shifts to the resonance frequency of an encapsulated bubble, or bubble shape deviates from sphericity, the localized high pressure becomes even greater.%基于流体力学,导出了超声驱动下的非球形包膜微泡的外部流体压强的解析表达式。数值模拟表明,虽然包膜微泡的非球形状对远场流体压强没有明显影响,但会造成近场局部位置有极大的流体压强,其明显高于同等条件下的球形包膜微泡周围相应位置上的流体压强。这一现象对包膜微泡的实际应用,如强超声治疗、靶向给药和细胞微穿孔等有着重要的意义。随着驱动频率向包膜微泡本征频率的靠近或微泡偏离球形程度的增大,所产生的近场局部高压也越大。

  7. Breathing life into aspheric dreams

    Science.gov (United States)

    Fuchs, Ulrike; Kiontke, Sven R.

    2016-06-01

    Introducing aspheric lenses in optical design broadens the horizons of possibilities and opens up new way to correct aberrations or creating effects that are not possible otherwise. Manufacturing these aspheric surfaces has come a long way during the last 15 years. This article discusses the state of the art concerning optical design, manufacturing, surface form tolerances and roughness to show the possibilities in hand.

  8. Aspherics in spectacle lenses

    Science.gov (United States)

    Dürsteler, Juan Carlos

    2016-12-01

    A review of the use of aspherics in the last decades, understood in a broad sense as encompassing single-vision lenses with conicoid surfaces and free-form and progressive addition lenses (PALs) as well, is provided. The appearance of conicoid surfaces to correct aphakia and later to provide thinner and more aesthetically appealing plus lenses and the introduction of PALs and free-form surfaces have shaped the advances in spectacle lenses in the last three decades. This document basically considers the main target optical aberrations, the idiosyncrasy of single lenses for correction of refractive errors and the restrictions and particularities of PAL design and their links to science vision and perception.

  9. ASPHERICAL SURFACES APPROXIMATION IN AUTOMATED DESIGN OF OPTICAL SYSTEMS

    Directory of Open Access Journals (Sweden)

    T. V. Ivanova

    2015-07-01

    Full Text Available Subject of Research. The paper deals with the problems of higher order aspherical surfaces approximation using different equation types. The objects of research are two types of equations for higher order aspherical surfaces description used in different software for optical systems design (SАRО, OPAL, ZEMAX, CODE-V, etc. and dependent on z-coordinate or on a radial coordinate on the surface. Conversion from one type of equations to another is considered in view of application in different software for optical systems design. Methods. The subject matter of the method lies in usage of mean square method approximation for recalculation of high-order aspherical surface. Iterative algorithm for recalculation is presented giving the possibility to recalculate coefficients for different types of equations with required accuracy. Recommendations are given for choosing recalculation parameters such as the number of result equation coefficients, the number of points for recalculation and point allocation on a surface. Main Results. Example of recalculation for aspherical surface and accuracy estimation, including result aberration comparison between initial surface and recalculated surface are presented. The example has shown that required accuracy of surface representation was obtained. Practical Relevance. This technique is usable for recalculation of higher order aspherical surfaces in various types of software for optical systems design and also for research of optimal higher order aspherical surfaces description.

  10. Non-null annular subaperture stitching interferometry for aspheric test

    Science.gov (United States)

    Zhang, Lei; Liu, Dong; Shi, Tu; Yang, Yongying; Chong, Shiyao; Miao, Liang; Huang, Wei; Shen, Yibing; Bai, Jian

    2015-10-01

    A non-null annular subaperture stitching interferometry (NASSI), combining the subaperture stitching idea and non-null test method, is proposed for steep aspheric testing. Compared with standard annular subaperture stitching interferometry (ASSI), a partial null lens (PNL) is employed as an alternative to the transmission sphere, to generate different aspherical wavefronts as the references. The coverage subaperture number would thus be reduced greatly for the better performance of aspherical wavefronts in matching the local slope of aspheric surfaces. Instead of various mathematical stitching algorithms, a simultaneous reverse optimizing reconstruction (SROR) method based on system modeling and ray tracing is proposed for full aperture figure error reconstruction. All the subaperture measurements are simulated simultaneously with a multi-configuration model in a ray-tracing program, including the interferometric system modeling and subaperture misalignments modeling. With the multi-configuration model, full aperture figure error would be extracted in form of Zernike polynomials from subapertures wavefront data by the SROR method. This method concurrently accomplishes subaperture retrace error and misalignment correction, requiring neither complex mathematical algorithms nor subaperture overlaps. A numerical simulation exhibits the comparison of the performance of the NASSI and standard ASSI, which demonstrates the high accuracy of the NASSI in testing steep aspheric. Experimental results of NASSI are shown to be in good agreement with that of Zygo® VerifireTM Asphere interferometer.

  11. Single-mask microfabrication of aspherical optics using KOH anisotropic etching of Si.

    Science.gov (United States)

    de Lima Monteiro, D W; Akhzar-Mehr, O; Sarro, P M; Vdovin, G

    2003-09-08

    We report on the microfabrication of continuous aspherical optical surfaces with a single-mask process, using anisotropic etching of silicon in a KOH water solution. Precise arbitrary aspherical surfaces with lateral scales on the order of several millimeters and a profile depth on the order of several micrometers were fabricated using this process. We discuss the factors defining the precision of the formed component and the resulting surface quality. We demonstrate 1 mm and 5 mm replicated aspherical phase plates, reproducing defocus, tilt, astigmatism and high-order aberrations. The technology has a potential for serial production of reflective and refractive arbitrary aspherical micro-optical components.

  12. Single-mask microfabrication of aspherical optics using KOH anisotropic etching of Si

    Science.gov (United States)

    de Lima Monteiro, D. W.; Akhzar-Mehr, O.; Sarro, P. M.; Vdovin, G.

    2003-09-01

    We report on the microfabrication of continuous aspherical optical surfaces with a single-mask process, using anisotropic etching of silicon in a KOH water solution. Precise arbitrary aspherical surfaces with lateral scales on the order of several millimeters and a profile depth on the order of several micrometers were fabricated using this process. We discuss the factors defining the precision of the formed component and the resulting surface quality. We demonstrate 1 mm and 5 mm replicated aspherical phase plates, reproducing defocus, tilt, astigmatism and high-order aberrations. The technology has a potential for serial production of reflective and refractive arbitrary aspherical micro-optical components.

  13. Surface Management System Departure Event Data Analysis

    Science.gov (United States)

    Monroe, Gilena A.

    2010-01-01

    This paper presents a data analysis of the Surface Management System (SMS) performance of departure events, including push-back and runway departure events.The paper focuses on the detection performance, or the ability to detect departure events, as well as the prediction performance of SMS. The results detail a modest overall detection performance of push-back events and a significantly high overall detection performance of runway departure events. The overall detection performance of SMS for push-back events is approximately 55%.The overall detection performance of SMS for runway departure events nears 100%. This paper also presents the overall SMS prediction performance for runway departure events as well as the timeliness of the Aircraft Situation Display for Industry data source for SMS predictions.

  14. Departure from equilibrium of the quasiparticle distribution functions in high-energy nuclear collisions

    Science.gov (United States)

    Chakraborty, P.; Kapusta, J. I.

    2017-01-01

    In simulations of high energy heavy ion collisions that employ viscous hydrodynamics, single particle distributions are distorted from their thermal equilibrium form due to gradients in the flow velocity. These are closely related to the formulas for the shear and bulk viscosities in the quasiparticle approximation. Distorted single particle distributions are now commonly used to calculate the emission of photons and dilepton pairs, and in the late stage to calculate the conversion of a continuous fluid to individual particles. We show how distortions of the single particle distribution functions due to both shear and bulk viscous effects can be done rigorously in the quasiparticle approximation and illustrate it with the linear σ model at finite temperature.

  15. ELID Grinding of Large Aspheric Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Large aperture aspheric optics are among the most susceptible optical surfaces to the accumulation of periodic surface artifacts during fabrication. Periodic...

  16. High brightness three-dimensional light field display based on the aspheric substrate Fresnel-lens-array with eccentric pupils

    Science.gov (United States)

    Gao, Xin; Sang, Xinzhu; Yu, Xunbo; Cao, Xuemei; Chen, Zhidong; Yan, Binbin; Yuan, Jinhui; Wang, Kuiru; Yu, Chongxiu; Dou, Wenhua; Xiao, Liquan

    2016-02-01

    The brightness and viewing field of the reproductive three-dimensional (3D) image are crucial factors to realize a comfortable 3D perception for the light field display based on the liquid crystal device (LCD). To improve the illuminance of 3D image with sub-image-units with small aperture angles and enlarge the viewing field, the illuminance of the Fresnel-lens combining with the sub-images on LCD is analyzed and designed. Theoretical and experimental results show that the Fresnel-lens-array with eccentric pupil(FAEP) can address above problems. A 3D light field display based on LCD with FAEP and directional diffuser screen are used to reconstruct the target 3D field. 25 parallax sub-images are projected to the directional diffuser screen to verify the improvement of illuminance and viewing field. To reduce eccentric aberration introduced by eccentric pupil, a novel structure of Fresnel-lens-array is presented to reduce the aberration. The illuminance and viewing field are well promoted at the same time. 3D image with the high quality can be achieved.

  17. Flexible interferometry for optical aspheric and free form surfaces

    Science.gov (United States)

    Zhang, Lei; Li, Dong; Liu, Yu; Bai, Yusi; Li, Jingsong; Yu, Benli

    2017-09-01

    A flexible interferometry is proposed to test concave optical aspheric and free-form surfaces. It employs a flexible aberration generator (FAG) consisting of a movable reflective sphere (MRS) and two counter-rotating optical wedges (CROW). The FAG is able to generate low-order Zernike aberrations to compensate the inherent aberrations of the test surface by the rotation of wedges in CROW and translation (or tilt) of the MRS. For some surfaces with mild departure, the FAG would result in a resolvable interferogram by the different aberrations compensation and the flexible test is thus achieved. The practical calibration for FAG is also reported. After calibration, experiment results showing the validity of the flexible test are presented by testing an ellipsoidal mirror and an off-axis paraboloidal mirror.

  18. Development of fabricating method for optical aspheric surface and fabricating method for high accuracy quadric surface mirror for solar furnace; Kogaku hikyumen no seisakuho no kaihatsu kara taiyoroyo koseido niji kyokumenkyo no sakuseiho made

    Energy Technology Data Exchange (ETDEWEB)

    Shishido, K. [Tohoku Gakuin Univ., Miyagi (Japan). Faculty of Engineering

    1996-03-29

    45 years have passed since the initiation of study on the fabricating method for optical aspheric surface. As examples of making prototypes for the `cam system,` fabrications of ellipsoidal surface mirror, parabolic mirror, segment type parabolic mirror, and particularly special asymmetric aspheric surface lens are quoted as successful cases. As regards the `link` system, a parabolic surface finishing machine for making matrices for soft formation of parabolic mirror segment glass was made on trial basis. Recently, a prototype of finishing machine for making a quadric surface finishing machine with higher accuracy was produced, which enabled preparation of more accurate matrices than in the past in the field of parabolic surface finishing machine, and actual ellipsoidal surface was machined by an ellipsoidal surface finishing machine. As regards solar furnace, study had been made to develop a method of producing a segment type glass mirror comprising a main mirror and a sub-mirror by a comparatively simple method and at high accuracy, and a promising result was obtained. 35 figs.

  19. Annular sub-aperture stitching interferometry testing for large-caliber aspheric

    Science.gov (United States)

    Wu, Pengfei; Yang, Shuming; Sun, Lin; Zhao, Pu; Jiang, Zhuangde

    2016-09-01

    An annular sub-aperture stitching interferometry testing is proposed for large-caliber aspheric lens testing, expanding the dynamic range of the interferometer, broadening the scope of the measurement, and reducing the cost of the measurement to a large extent without the use of compensating elements. The large-caliber aspheric is divided into several annular sub-apertures, and there are some overlapping areas between each two adjacent sub-apertures. When testing, the test aspheric is moved along the optical axis according to path planning so that the reference spherical shape and the test aspheric interest at points of common tangency to reduce the fringe density of the sub-aperture. However, in the process of moving the test optic, six DOF (degrees of freedom) misalignment errors will occur. According to the rigid body kinematics theory, the misalignment error separation model is established so that the misalignment factors can be calculated by the information of each overlapping regions. Then all sub-apertures are unified to the same reference with proper algorithm, and subsequently, misalignment error of the reference is removed by Zernike polynomial fitting, and the whole surface error is recovered. Simulation results are shown to demonstrate the feasibility of the method we developed. By analyzing the influence of the six DOF on the stitching result, the most important factor is obtained, and some measures are taken, that is, a measurement system combining two interferometers is designed, one of which is to measure the departures between the reference and the aspheric, and another to test the piston errors to be transmitted to the control system to improve the accuracy.

  20. Review of small aspheric glass lens molding technologies

    Science.gov (United States)

    Yin, Shaohui; Jia, Hongpeng; Zhang, Guanhua; Chen, Fengjun; Zhu, Kejun

    2017-01-01

    Aspheric lens can eliminate spherical aberrations, coma, astigmatism, field distortions, and other adverse factors. This type of lens can also reduce the loss of light energy and obtain high-quality images and optical characteristics. The demand for aspheric lens has increased in recent years because of its advantageous use in the electronics industry, particularly for compact, portable devices and high-performance products. As an advanced manufacturing technology, the glass lens molding process has been recognized as a low-cost and high-efficiency manufacturing technology for machining small-diameter aspheric lens for industrial production. However, the residual stress and profile deviation of the glass lens are greatly affected by various key technologies for glass lens molding, including glass and mold-die material forming, mold-die machining, and lens molding. These key technical factors, which affect the quality of the glass lens molding process, are systematically discussed and reviewed to solve the existing technical bottlenecks and problems, as well as to predict the potential applicability of glass lens molding in the future.

  1. A novel in-situ measuring technique for aspheric surface

    Science.gov (United States)

    Zhang, Chuan; Wang, Ping; Chen, Yaolong

    2011-11-01

    In this paper, a novel in-situ surface measuring technique for optical elements with aspheric surface is presented. It is a contact type probe, and can be used for measuring ground surfaces. The theory of this technique develops from coordinate measuring machine (CMM), and the measurement accuracy of this technique is depended on the accuracy of computer numerical controlled (CNC). By installing a special equipment with high accuracy measuring head in main spindle of CNC machine, and moving the probe along the path which is described by a mathematical aspheric expression precisely, we could get relative errors of sag height of any position in this path. With this technique, the repeat positioning error caused by traditional off-line measurement will be avoided. The author also has finished a special software with VC++ 6.0. With this software, the form error of ground work piece could be corrected rapidly. This software can calculate and handle the arrangement automatically with all parameters which are required to input in operation interface. In the correction stage, the software can analyze and process error data and generate a new NC program with corrected data for next grinding stage. After 2 or 3 times measuring and correction, the surface shape error of the aspheric optical element will be less than 1μm. The finished work piece has a very good surface finish and can be polished with high quality.

  2. Measurement of large aspheric surfaces by annular subaperture stitching interferometry

    Institute of Scientific and Technical Information of China (English)

    Xiaokun Wang; Lihui Wang; Longhai Yin; Binzhi Zhang; Di Fan; Xuejun Zhang

    2007-01-01

    A new method for testing aspheric surfaces by annular subaperture stitching interferometry is introduced.It can test large-aperture and large-relative-aperture aspheric surfaces at high resolution, low cost, and high efficiency without auxiliary null optics. The basic principle of the method is described, the synthetical optimization stitching model and effective algorithm are established based on simultaneous least-square fitting. A hyperboloid with an aperture of 350 mm is tested by this method. The obtained peak-to-valley (PV) and root-mean-square (RMS) values of the surface error after stitching are 0.433λ and 0.052λ (λis 632.8 nm), respectively. The reconstructed surface map is coincide with the entire surface map from null test, and the difference of PV and RMS errors between them are 0.031λ and 0.005λ, respectively.This stitching model provides another quantitive method for testing large aspheric surfaces besides null compensation.

  3. Corneal topography with conical null-screen for non-symmetric aspheric corneas

    Science.gov (United States)

    Armengol-Cruz, Victor de Emanuel; Osorio-Infante, Arturo I.; Campos-García, Manuel; Cossio-Guerrero, Cesar; Díaz-Uribe, José Rufino

    2016-09-01

    In this work, we will present some improvements to the conical null-screen based corneal topographer, for testing aspheric surfaces without rotational symmetry. We present the formulae to design the conical null-screen in such a way that the image on the CCD is a perfect array of spots; departures from this geometry are due to deformation or misalignment of the surface. Additionally, we will explain how to improve the algorithms to find the normals of corneal surface. Finally, we will evaluate the topography of a spherical surface.

  4. Treating asphericity in fuel particle pressure vessel modeling

    Science.gov (United States)

    Miller, Gregory K.; Wadsworth, Derek C.

    1994-07-01

    The prototypical nuclear fuel of the New Production Modular High Temperature Gas-Cooled Reactor (NP-MHTGR) consists of spherical TRISO-coated particles suspended in graphite cylinders. The coating layers surrounding the fuel kernels in these particles consist of pyrolytic carbon layers and a silicon carbide layer. These coating layers act as a pressure vessel which retains fission product gases. In the operating conditions of the NP-MHTGR, a small percentage of these particles (pressure vessels) are expected to fail due to the pressure loading. The fuel particles of the NP-MHTGR deviate to some degree from a true spherical shape, which may have some effect on the failure percentages. A method is presented that treats the asphericity of the particles in predicting failure probabilities for particle samples. It utilizes a combination of finite element analysis and Monte Carlo sampling and is based on the Weibull statistical theory. The method is used here to assess the effects of asphericity in particles of two common geometric shapes, i.e. faceted particles and ellipsoidal particles. The method presented could be used to treat particle anomalies other than asphericity.

  5. Phase-locked-loop interferometry applied to aspheric testing with a computer-stored compensator.

    Science.gov (United States)

    Servin, M; Malacara, D; Rodriguez-Vera, R

    1994-05-01

    A recently developed technique for continuous-phase determination of interferograms with a digital phase-locked loop (PLL) is applied to the null testing of aspheres. Although this PLL demodulating scheme is also a synchronous or direct interferometric technique, the separate unwrapping process is not explicitly required. The unwrapping and the phase-detection processes are achieved simultaneously within the PLL. The proposed method uses a computer-generated holographic compensator. The holographic compensator does not need to be printed out by any means; it is calculated and used from the computer. This computer-stored compensator is used as the reference signal to phase demodulate a sample interferogram obtained from the asphere being tested. Consequently the demodulated phase contains information about the wave-front departures from the ideal computer-stored aspheric interferogram. Wave-front differences of ~ 1 λ are handled easily by the proposed PLL scheme. The maximum recorded frequency in the template's interferogram as well as in the sampled interferogram are assumed to be below the Nyquist frequency.

  6. Clinical study of customized aspherical intraocular lens implants

    Institute of Scientific and Technical Information of China (English)

    Lie-Xi; Jia; Zhao-Hui; Li

    2014-01-01

    AIM:To compare if there is an improvement in visual functions with age-related cataracts between patients receiving a aspherical intraocular lens(IOL) based on corneal wavefront aberration and patients randomly assigned lenses.METHODS:A total of 124 eyes of 124 patients with age-related cataracts were placed in experimental group and a group receiving randomly assigned(RA) lenses.The experimental group was undergone Pentacam corneal spherical aberration measurement before surgery; the targeted range for residual total spherical aberration after surgery was set to 0-0.3 μm. Patients with a corneal spherical aberration <0.3 μm were implanted with a zero-spherical aberration advanced optics(AO) aspherical IOL and patients with an aberration ≥0.3 μm received a Tecnis Z9003 aspherical lens in experimental group. RA patients were randomly implanted with an AO lens or a Tecnis Z9003 lens. Three months after surgery total spherical aberration, photopic/mesopic contrast sensitivities, photopic/mesopic with glare contrast sensitivities, and logMAR vision were measured.RESULTS:Statistical analysis on logMAR vision showed no significant difference between two groups(P =0.413). The post-surgical total spherical aberration was 0.126 ±0.097 μm and 0.152 ±0.151 μm in the experimental and RA groups, respectively(P =0.12). The mesopic contrast sensitivities at spatial frequencies of 6,12 and 18 c/d in the experimental group were significantly higher than of the RA group(P =0.00; P =0.04;P =0.02). The mesopic with glare contrast sensitivity in the experimental group at a spatial frequency of 18 c/d was also significantly higher vs the RA group(P =0.01).CONCLUSION:Pre-surgical corneal spherical aberration measurement in cataract patients followed bycustomized selection of aspherical IOL implants improved mesopic contrast sensitivities at high spatial frequencies, and thus is a superior strategy compared to the random selection of aspherical intraocular lens implants.

  7. Profiling of aspherical surfaces using moire deflectometry

    Science.gov (United States)

    Uitterdijk, T.; Frankena, Hans J.; Smorenburg, Kees

    1994-11-01

    An elegant measuring setup for contouring strong aspherical surfaces is introduced. Moire deflectometry is chosen as the measuring method because the configuration is simple, robust, and variable in sensitivity. The instrument is capable of measuring height deviations between an aspherical surface and its best fitting sphere ranging from minimally 1 micrometers to maximally 30 micrometers with a relative accuracy of 10%, which is useful for the production of surfaces in infrared optics. It is possible to measure transparent as well as reflecting surfaces, both convex and concave. A CCD-camera and a PC make part of the setup to automate the measurements. The short measurement time of less than 60 seconds makes the instrument useful in the manual production of aspherical surfaces.

  8. 高陡度保形光学非球面环形子孔径检测方法%Testing methods of high-gradient conformal aspheric surfaces based on annular sub-aperture stitching

    Institute of Scientific and Technical Information of China (English)

    王洪浩; 明名; 吕天宇; 邹惠莹

    2016-01-01

    环形子孔径拼接技术检测大口径、高陡度光学非球面具有低成本、高效率的特点.提出一种基于最小二乘法和泽尼克多项式拟合的环形子孔径拼接方法检测高陡度光学非球面.研究了环形子孔径拼接算法的基本原理,对环形子孔径的划分方式进行数学公式推导及参数运算,建立被测非球面的有效数学模型.全口径的拼接结果与原始波面基本一致,二者PV和RMS差值分别为0.0151λ、0.0047λ(λ为632.8 nm),残差的PV和RMS值为0.0435λ、0.0052λ,验证该算法的有效性和准确性.%Annular sub-aperture stitching interferometry technology can test steep conformal aspheric surfaces with low cost and high efficiency without auxiliary null optics. The effective splicing algorithm was established based on simultaneous least-squares method and Zernike polynomial fitting. Firstly, the basic principle of the algorithm of the annular sub-aperture stitching was studied. Secondly, the mathematical formulas of the sub-aperture effective area were derived and the parameters of the sub-aperture effective area were calculated and optimized. Finally, the reasonable mathematical model was established. The detection method of annular sub-aperture stitching high steepness aspheric has been tested through on experimental verification. As a result, the surface map of the full aperture after stitching was consistent to the input surface map, the difference of PV error and RMS error between them is 0.0151λand 0.0047λ (λ is 632.8 nm); the PV and RMS of residual error of full aperture phase distribution is 0.0435λ and 0.0052λ. The results conclude that this splicing model and algorithm were accurate and feasible.

  9. Measurement of nucleation site density, bubble departure diameter and frequency in pool boiling of water using high-speed infrared and optical cameras

    Energy Technology Data Exchange (ETDEWEB)

    Gerardi, Craig; Buongiorno, Jacopo; Hu, Lin-wen; McKrell, Thomas [Massachusetts Institute of Technology, Cambridge, MA (United States)], e-mail: jacopo@mit.edu

    2009-07-01

    A high-speed video and IR thermometry based technique has been used to obtain time and space resolved information on bubble nucleation and boiling heat transfer. This approach provides a fundamental and systematic method for investigating nucleate boiling in a very detailed fashion. Data on bubble departure diameter and frequency, growth and wait times, and nucleation site density are measured with relative ease. The data have been compared to the traditional decades-old and poorly-validated nucleate-boiling models and correlations. The agreement between the data and the models is relatively good. This study also shows that new insights into boiling heat transfer mechanisms can be obtained with the present technique. For example, our data and analysis suggest that a large contribution to bubble growth comes from heat transfer through the superheated liquid layer in addition to micro layer evaporation. (author)

  10. Research on testing method for combined aspheric surface with non-rotational symmetric

    Science.gov (United States)

    Zhou, Wencai; Xu, Feng; Wei, Xiaoxiao

    2016-09-01

    Non-rotational symmetric aspheric surface has many significant advantages, but it still can not be widely used because the limiting that there is no method can tests it precisely. At present, the coordinate contour measuring machine is the main testing method for the aspheric surface with non-rotational symmetric, but the measurement accuracy of this method is not high. In this paper, the method of diffraction compensator (computed graphic holograph) has been adopted to test the combined aspheric surface, which can compensate the phase caused by tested lens. The sample surface is the combined aspheric surface with diameter of 33.84mm, and the process from optical software simulation design, the fabrication of the computed graphic holograph (CGH) to experimental platform built is given in detail after testing via the CGH technology. The simulation results show that the root mean square (RMS) of remnant wave-front error is 0.004 λ, and the peak to valley (PV) is 0.0245 λ. The free-from surface has been tested by Zygo interferometer, and the experimental results show that the RMS is 0.49 λ, the PV is 4.69 λ. The accuracy of the result is higher than that of coordinate contour measuring machine. The system error caused by optical elements analysed is 0.1149λ. The accurate result means that the CGH technology for testing the combined aspheric surface is realized.

  11. Study on error analysis and accuracy improvement for aspheric profile measurement

    Science.gov (United States)

    Gao, Huimin; Zhang, Xiaodong; Fang, Fengzhou

    2017-06-01

    Aspheric surfaces are important to the optical systems and need high precision surface metrology. Stylus profilometry is currently the most common approach to measure axially symmetric elements. However, if the asphere has the rotational alignment errors, the wrong cresting point would be located deducing the significantly incorrect surface errors. This paper studied the simulated results of an asphere with rotational angles around X-axis and Y-axis, and the stylus tip shift in X, Y and Z direction. Experimental results show that the same absolute value of rotational errors around X-axis would cause the same profile errors and different value of rotational errors around Y-axis would cause profile errors with different title angle. Moreover, the greater the rotational errors, the bigger the peak-to-valley value of profile errors. To identify the rotational angles in X-axis and Y-axis, the algorithms are performed to analyze the X-axis and Y-axis rotational angles respectively. Then the actual profile errors with multiple profile measurement around X-axis are calculated according to the proposed analysis flow chart. The aim of the multiple measurements strategy is to achieve the zero position of X-axis rotational errors. Finally, experimental results prove the proposed algorithms achieve accurate profile errors for aspheric surfaces avoiding both X-axis and Y-axis rotational errors. Finally, a measurement strategy for aspheric surface is presented systematically.

  12. Aspheric surface testing by irradiance transport equation

    Science.gov (United States)

    Shomali, Ramin; Darudi, Ahmad; Nasiri, Sadollah; Asgharsharghi Bonab, Armir

    2010-10-01

    In this paper a method for aspheric surface testing is presented. The method is based on solving the Irradiance Transport Equation (ITE).The accuracy of ITE normally depends on the amount of the pick to valley of the phase distribution. This subject is investigated by a simulation procedure.

  13. Aspherical surfaces design for extreme ultraviolet lithographic objective with correction of thermal aberration

    Science.gov (United States)

    Liu, Yan; Li, Yanqiu

    2016-09-01

    At present, few projection objectives for extreme ultraviolet (EUV) lithography pay attention to correct thermal aberration in optical design phase, which would lead to poor image quality in a practical working environment. We present an aspherical modification method for helping the EUV lithographic objective additionally correct the thermal aberration. Based on the thermal aberration and deformation predicted by integrated optomechanical analysis, the aspherical surfaces in an objective are modified by an iterative algorithm. The modified aspherical surfaces could correct the thermal aberration and maintain the initial high image quality in a practical working environment. A six-mirror EUV lithographic objective with 0.33-numerical aperture is taken as an example to illustrate the presented method. The results show that the thermal aberration can be corrected effectively, and the image quality of the thermally deformed system is improved to the initial design level, which proves the availability of the method.

  14. Optimization on manufacturing and testing technology for rectangle aperture off-axis aspheric mirror fine grinding

    Science.gov (United States)

    Chen, Xi; Guo, Peiji; Wang, Dongdong

    2016-10-01

    High precision aspheric surface can be obtained conveniently by using single point diamond turning technology, liquidmagnetic polishing technology and ion beam polishing technology, but the costs of manufacturing is too enormous to be widely used. In fact, in the field of optical processing, the most commonly used technical solution is still making a best fit sphere firstly compared with aspheric equation, and then remove the material on the glass to correct the error between aspheric and best fit sphere by precision grinding and precision polishing. The resolving of the best-fit sphere and the material removal, however, is a very important problem during the fabrications. The two dimensional maps of surface error between the best fit sphere and the corresponding aspheric surface shows W shaped which has the maximum removal at the center and the edge of the workpeace and gradually reduces to zero at the 70.7 percent of the diameter. In the process of deterministic optical manufacturing, the edge effect will arise because of the change of machining conditions when polishing tool locates in edge area, which will lower the surface accuracy of workpiece and debase machining efficiency. W shaped error distribution and the edge effect will make it difficult to remove the error on the edge of the workpiece. Aiming at the situation, an algorithm available for control of edge effect is proposed. Considering the requirement of minimum material removal and the control of edge effect, the radius of the anti-edge effect sphere is calculated by programming. The advantage of the algorithm is shown by the comparison of results derived from new algorithm and empirical equation. At the same time, the application in the off-axis asphere fabrications also proves the correctness of the algorithm. This algorithm is very helpful for the theory and practice of the fabrications of off-axis asphere.

  15. From Spheric to Aspheric Solid Polymer Lenses: A Review

    Directory of Open Access Journals (Sweden)

    Kuo-Yung Hung

    2011-01-01

    Full Text Available This paper presents a new approach in the use of MEMS technology to fabricate micro-optofluidic polymer solid lenses in order to achieve the desired profile, focal length, numerical aperture, and spot size. The resulting polymer solid lenses can be applied in optical data storage systems, imaging systems, and automated optical inspection systems. In order to meet the various needs of different applications, polymer solid lenses may have a spherical or aspherical shape. The method of fabricating polymer solid lenses is different from methods used to fabricate tunable lenses with variable focal length or needing an external control system to change the lens geometry. The current trend in polymer solid lenses is toward the fabrication of microlenses with a high numerical aperture, small clear aperture (<2 mm, and high transmittance. In this paper we focus on the use of thermal energy and electrostatic force in shaping the lens profile, including both spherical and aspherical lenses. In addition, the paper discusses how to fabricate a lens with a high numerical aperture of 0.6 using MEMS and also compares the optical characteristics of polymer lens materials, including SU-8, Norland Optical Adhesive (NOA, and cyclic olefin copolymer (COC. Finally, new concepts and applications related to micro-optofluidic lenses and polymer materials are also discussed.

  16. Justifying departures from progressivity

    DEFF Research Database (Denmark)

    Heinemann, Trine; Steensig, Jakob

    2017-01-01

    -going activity. Some of the actions that altså prefaces can also be prefaced by phrases like ‘you know’ or ‘I mean’, which seem to do at least some of the work that altså does, but altså is used more frequently and across a wider range of actions. In our discussion, we raise the possibility that the usefulness......This chapter investigates the use of the Danish particle altså in turn-initial position. Turn-initial altså can be employed for prefacing a wide range of actions, including self- and other-initiated repair, questions, second stories and answers to both yes/no and wh-questions. We show that across...... these actions, participants in interaction produce altså to indicate (1) that the action they will produce departs from progressivity, (2) that it will expand on something prior, (3) that the departure is, therefore, justified, and (4) that it will contribute to reinstalling the progression of the larger on...

  17. Ultra-precision molding of chalcogenide glass aspherical lens

    Science.gov (United States)

    Zhang, Feng; Wang, Zhibin; Zhang, Yunlong; Su, Ying; Guo, Rui; Xu, Zengqi; Liu, Xuanmin

    2016-10-01

    With the development of infrared optical systems in military and civil areas, chalcogenide glass aspherical lens possess some advantages, such as large infrared transmission, good thermal stability performance and image quality. Aspherical lens using chalcogenide glass can satisfy the requirements of modern infrared optical systems. Therefore, precision manufacturing of chalcogenide glass aspheric has received more and more attention. The molding technology of chalcogenide glass aspheric has become a research hotspot, because it can achieve mass and low cost manufacturing. The article of molding technology is focusing on a kind of chalcogenide glass aspherical lens. We report on design and fabrication of the mold that through simulation analysis of molding. Finally, through molding test, the fabrication of mold's surface and parameters of molding has been optimized, ensuring the indicators of chalcogenide glass aspherical lens meet the requirements.

  18. Asphericity analysis using corneal wavefront and topographic meridional fits

    Science.gov (United States)

    Arba-Mosquera, Samuel; Merayo-Lloves, Jesús; de Ortueta, Diego

    2010-03-01

    The calculation of corneal asphericity as a 3-D fit renders more accurate results when it is based on the corneal wavefront aberrations rather than on the corneal topography of the principal meridians. A more accurate prediction could be obtained for hyperopic treatments compared to myopic treatments. We evaluate a method to calculate corneal asphericity and asphericity changes after refractive surgery. Sixty eyes of 15 consecutive myopic patients and 15 consecutive hyperopic patients (n=30 each) are retrospectively evaluated. Preoperative and 3-month-postoperative topographic and corneal wavefront analyses are performed using corneal topography. Ablations are performed using a laser with an aberration-free profile. Topographic changes in asphericity and corneal aberrations are evaluated for a 6-mm corneal diameter. The induction of corneal spherical aberrations and asphericity changes correlates with the achieved defocus correction. Preoperatively as well as postoperatively, asphericity calculated from the topography meridians correlates with asphericity calculated from the corneal wavefront in myopic and hyperopic treatments. A stronger correlation between postoperative asphericity and the ideally expected/predicted asphericity is obtained based on aberration-free assumptions calculated from corneal wavefront values rather than from the meridians. In hyperopic treatments, a better correlation can be obtained compared to the correlation in myopic treatments. Corneal asphericity calculated from corneal wavefront aberrations represents a 3-D fit of the corneal surface; asphericity calculated from the main topographic meridians represents a 2-D fit of the principal corneal meridians. Postoperative corneal asphericity can be calculated from corneal wavefront aberrations with higher fidelity than from corneal topography of the principal meridians. Hyperopic treatments show a greater accuracy than myopic treatments.

  19. On the Departure from Equilibrium of the Quasi-Particle Distribution Functions in High Energy Nuclear Collisions

    CERN Document Server

    Chakraborty, P

    2016-01-01

    In high energy heavy ion collisions, single particle distributions are distorted from their thermal equilibrium form due to gradients in the flow velocity. These are closely related to the formulas for the shear and bulk viscosities in the quasi-particle approximation. Distorted single particle distributions are now commonly used to calculate the emission of photons and dilepton pairs, and in the late stage to calculate the conversion of a continuous fluid to individual particles. In practice this is done only in a very approximate way. We show how it can be done rigorously in the quasi-particle approximation and illustrate it with the linear $\\sigma$ model at finite temperature for both the shear and bulk contributions.

  20. ASPHERICITY AND PROLATENESS OF LINEAR AND CIRCULAR MACROMOLECULES

    Institute of Scientific and Technical Information of China (English)

    WEI Gaoyuan

    1995-01-01

    The shape asymmetry of gaussian models of linear and circular macromolecules has been numerically invesigated in terms of asphericity and prolateness parameters. These parameters are found to decrease with increasing length for the macromolecule either confined to a plane or in three dimensions. The effect of dimensionality on these parameters is visible only for low dimensions and is generally weak. As dimensionality goes to infinity, it is found that asphericity and prolateness for both chains and rings approach slowly yet descendingly values of corresponding asphericity and prolateness factors, with the exception of the chain which shows a minimum value of asphericity when the embedding space has a dimensionality of four.

  1. Corneal Asphericity and IOL Power Calculation in Eyes With Aspherical IOLs.

    Science.gov (United States)

    Savini, Giacomo; Hoffer, Kenneth J; Barboni, Piero; Schiano Lomoriello, Domenico; Ducoli, Pietro

    2017-07-01

    Given that a previous study found that corneal asphericity influences the refractive outcome of intraocular lens (IOL) power calculation by means of thin-lens formulas in eyes with spherical IOLs, the authors aimed to verify whether such influence can also be observed in eyes with aspherical IOLs. In this retrospective comparative case series, IOL power was calculated with the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas in two groups of eyes undergoing phacoemulsification and implantation of an aspherical IOL (Acrysof SN60WF; Alcon Laboratories, Inc., Fort Worth, TX). For each formula, the refractive prediction error was calculated once the constants had been optimized. Biometric data were obtained by partial coherence interferometry in one group and immersion ultrasound biometry and corneal topography in the other. Corneal asphericity was assessed by two different corneal topographers in the optical biometry group (Magellan; Nidek, Gamagori, Japan) and ultrasound biometry group (Keratron, Optikon 2000 Spa, Rome, Italy). The mean Q-value was -0.12 ± 0.08 in the optical biometry group (n = 51) and -0.22 ± 0.14 in the ultrasound biometry group (n = 79). In both groups, linear regression disclosed a statistically significant correlation between the Q-value and the prediction error (the only exception being the SRK/T formula). More negative Q-values were correlated to a positive prediction error, indicating a myopic outcome for prolate corneas. However, the correlation coefficients were lower than those previously reported for spherical IOLs. Corneal asphericity also influences the refractive outcomes of IOL power calculation by thinlens formulas when aspherical IOLs are implanted, although this influence is exerted to a lesser degree compared to spherical IOLs. [J Refract Surg. 2017;33(7):476-481.]. Copyright 2017, SLACK Incorporated.

  2. Ultra-precision diamond milling of aspheric microlens array

    Science.gov (United States)

    Chen, Chun-Chieh; Huang, Chien-Yao; Cheng, Yuan-Chieh; Hsu, Wei-Yao

    2013-06-01

    The applications of AMLA (aspheric micro lens array) have been frequently required in opto-electro industries, such as optical communication, contact image sensor (CIS) module of scanner, wafer level optics, etc. In addition to the typical requirements of aspheric lens, for instance form accuracy and surface roughness, the pitch error of each micro lens has been highly required. Three ultra-precision freeform machining methods have been widely applied for the manufacturing of AMLA, namely fast tool servo, slow tool servo and diamond milling. UPDM (Ultra-precision diamond milling) have the advantage with no tool interference problem in comparison with tool servo machining techniques. In this paper, the tool setting error compensation method and the tool path of UPDM has been developed for the fabrication of a 5 by 5 AMLA model. The form accuracy and surface roughness of each lenses of the AMLA was less than 0.2μm and 5nm, respectively. And the pitch error of each micro lens was less than 2μm in 25 micro lenses.

  3. Implementation of Bluetooth technology in processing aspheric mirrors

    Science.gov (United States)

    Chen, Dong-yun; Li, Xiao-jin

    2010-10-01

    This paper adopts the Bluetooth wireless transmission to replace the conducting rings currently using in the active lap process to overcome the cost and abrasion problems brought by the conducting rings, which has great significance for reducing the costs of processing large aspheric mirrors. Based on the actual application requirements, Article proposes the overall program of using Bluetooth technology as data transmission, including the active lap-side and machine tool-side: In the machine tool-side, the MCU separately connects with Bluetooth module and the sensor via UART0 and UART1 serial port, and when the MCU receives the signals sending from the sensor, the MCU packs and then sends them through the Bluetooth module; while in the active lap side, the CCAL reads-out the position signals of sensor detecting in dual-port memory via one-side ports, and the other side ports connect with the MCU's high ports P4-P7, so the MCU can unpacks and stores the position signals receiving via Bluetooth module. This paper designs and implements the system's hardware circuit, and mainly introduces the ways of serial and parallel. Based upon the realized system, design the test program for the Bluetooth wireless transmission and the experiment results, in the condition of the active lap processing large aspheric mirrors, showed that Bluetooth technology can meet the requirements of practical applications.

  4. New procedure for departure formalities

    CERN Multimedia

    HR & GS Departments

    2011-01-01

    As part of the process of simplifying procedures and rationalising administrative processes, the HR and GS Departments have introduced new personalised departure formalities on EDH. These new formalities have applied to students leaving CERN since last year and from 17 October 2011 this procedure will be extended to the following categories of CERN personnel: Staff members, Fellows and Associates. It is planned to extend this electronic procedure to the users in due course. What purpose do departure formalities serve? The departure formalities are designed to ensure that members of the personnel contact all the relevant services in order to return any necessary items (equipment, cards, keys, dosimeter, electronic equipment, books, etc.) and are aware of all the benefits to which they are entitled on termination of their contract. The new departure formalities on EDH have the advantage of tailoring the list of services that each member of the personnel must visit to suit his individual contractual and p...

  5. Practical retrace error correction in non-null aspheric testing: A comparison

    Science.gov (United States)

    Shi, Tu; Liu, Dong; Zhou, Yuhao; Yan, Tianliang; Yang, Yongying; Zhang, Lei; Bai, Jian; Shen, Yibing; Miao, Liang; Huang, Wei

    2017-01-01

    In non-null aspheric testing, retrace error forms the primary error source, making it hard to recognize the desired figure error from the aliasing interferograms. Careful retrace error correction is a must bearing on the testing results. Performance of three commonly employed methods in practical, i.e. the GDI (geometrical deviation based on interferometry) method, the TRW (theoretical reference wavefront) method and the ROR (reverse optimization reconstruction) method, are compared with numerical simulations and experiments. Dynamic range of these methods are sought out and the application is recommended. It is proposed that with aspherical reference wavefront, dynamic range can be further enlarged. Results show that the dynamic range of the GDI method is small while that of the TRW method can be enlarged with aspherical reference wavefront, and the ROR method achieves the largest dynamic range with highest accuracy. It is recommended that the GDI and TRW methods be applied to apertures with small figure error and small asphericity, and the ROR method for commercial and research applications calling for high accuracy and large dynamic range.

  6. Problems on design of computer-generated holograms for testing aspheric surfaces: principle and calculation

    Institute of Scientific and Technical Information of China (English)

    Zhishan Gao; Meimei Kong; Rihong Zhu; Lei Chen

    2007-01-01

    Interferometric optical testing using computer-generated hologram (CGH) has provided an approach to highly accurate measurement of aspheric surfaces. While designing the CGH null correctors, we should make them with as small aperture and low spatial frequency as possible, and with no zero slope of phase except at center, for the sake of insuring lowisk of substrate figure error and feasibility of fabrication. On the basis of classic optics, a set of equations for calculating the phase function of CGH are obtained. These equations lead us to find the dependence of the aperture and spatial frequency on the axial diszance from the tested aspheric surface for the CGH. We also simulatethe ptical path difference error of the CGH relative to the accuracy of controlling laser spot during fabrication. Meanwhile, we discuss the constraints used to avoid zero slope of phase except at center and give a design result of the CGH for the tested aspheric surface. The results ensure the feasibility of designing a useful CGH to test aspheric urface fundamentally.

  7. Coefficient of restitution of aspherical particles.

    Science.gov (United States)

    Glielmo, Aldo; Gunkelmann, Nina; Pöschel, Thorsten

    2014-11-01

    We consider the motion of an aspherical inelastic particle of dumbbell type bouncing repeatedly on a horizontal flat surface. The coefficient of restitution of such a particle depends not only on material properties and impact velocity but also on the angular orientation at the instant of the collision whose variance is considerable, even for small eccentricity. Assuming random angular orientation of the particle at the instant of contact we characterize the measured coefficient of restitution as a fluctuating quantity and obtain a wide probability density function including a finite probability for negative values of the coefficient of restitution. This may be understood from the partial exchange of translational and rotational kinetic energy.

  8. Diamond turning of aspheric steel molds for optics replication

    Science.gov (United States)

    Klocke, F.; Dambon, O.; Bulla, B.

    2010-02-01

    Diamond turning of steel parts is conventionally not possible due to the high tool wear. However this process would enable several different application with high economical innovative potential. One technology that enables the direct manufacturing of steel components with monocrystalline diamond is the ultrasonic assisted diamond turning process. This technology has been investigated over years within the Fraunhofer IPT and has proven its potential. Surface roughness in the range of Ra = 5 nm are reached and the diamond wear is reduced by a factor 100 or higher. Up to now this process has been investigated in lab conditions manufacturing only plane surfaces. In order to prove its industrial suitability, two relevant aspherical shapes, convex and concave respectively, have been defined and manufactured. The reached form accuracies and surface roughness values will be described in this paper.

  9. Aspheric Generation On Glass By Ion Beam Milling

    Science.gov (United States)

    Eisenberg, Naftali P.; Carouby, R.; Broder, Jack

    1989-07-01

    Due to the progress of the diamond turning technique, the use of aspheric elements in optical systems is increasing. However, there are materials, like glass, which are not compatible with this technique especially when the shape of the aspheric element is not a simple conic. Using ion beam milling through a mask which modulates spatially the amount of ions impinging on the surface to be shaped, a piano-convex glass lens has been transformed into an aspheric element with a conical front surface. This technique is valuable for any material used either in the visible or in the IR spectrum.

  10. Manufacturing aspheric mirrors made of zero thermal expansion cordierite ceramics using Magnetorheological Finishing (MRF)

    Science.gov (United States)

    Sugawara, Jun; Maloney, Chris

    2016-07-01

    NEXCERATM cordierite ceramics, which have ultra-low thermal expansion properties, are perfect candidate materials to be used for light-weight satellite mirrors that are used for geostationary earth observation and for mirrors used in ground-based astronomical metrology. To manufacture the high precision aspheric shapes required, the deterministic aspherization and figure correction capabilities of Magnetorheological Finishing (MRF) are tested. First, a material compatibility test is performed to determine the best method for achieving the lowest surface roughness of RMS 0.8nm on plano surfaces made of NEXCERATM ceramics. Secondly, we will use MRF to perform high precision figure correction and to induce a hyperbolic shape into a conventionally polished 100mm diameter sphere.

  11. An Instrument for Inspecting Aspheric Optical Surfaces and Components Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a Phase I proposal to develop an extremely versatile optical inspection tool for determining the optical figure of aspheric optical components, such as test...

  12. Error analysis of aspheric surface with reference datum.

    Science.gov (United States)

    Peng, Yanglin; Dai, Yifan; Chen, Shanyong; Song, Ci; Shi, Feng

    2015-07-20

    Severe requirements of location tolerance provide new challenges for optical component measurement, evaluation, and manufacture. Form error, location error, and the relationship between form error and location error need to be analyzed together during error analysis of aspheric surface with reference datum. Based on the least-squares optimization method, we develop a least-squares local optimization method to evaluate form error of aspheric surface with reference datum, and then calculate the location error. According to the error analysis of a machined aspheric surface, the relationship between form error and location error is revealed, and the influence on the machining process is stated. In different radius and aperture of aspheric surface, the change laws are simulated by superimposing normally distributed random noise on an ideal surface. It establishes linkages between machining and error analysis, and provides an effective guideline for error correcting.

  13. An Instrument for Inspecting Aspheric Optical Surfaces and Components Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a Phase II SBIR proposal to develop an extremely versatile optical inspection tool for aspheric optical components and optics that are not easily inspected...

  14. Low-Cost High-Precision PIAA Optics for High Contrast Imaging with Exo-Planet Coronagraphs

    Science.gov (United States)

    Balasubramanian, Kunjithapatham; Shaklan, Stuart B.; Pueyo, Laurent; Wilson, Daniel W.; Guyon, Olivier

    2010-01-01

    PIAA optics for high contrast imaging present challenges in manufacturing and testing due to their large surface departures from aspheric profiles at the aperture edges. With smaller form factors and consequent smaller surface deformations (<50 microns), fabrication of these mirrors with diamond turning followed by electron beam lithographic techniques becomes feasible. Though such a design reduces the system throughput to approx.50%, it still provides good performance down to 2 lambda/D inner working angle. With new achromatic focal plane mask designs, the system performance can be further improved. We report on the design, expected performance, fabrication challenges, and initial assessment of such novel PIAA optics.

  15. Research on the Parameter Optimization of Lines Connecting Main Line and Arrival -departure Line in High -speed Railway Station Yard%高速铁路站场正线与到发线间线路优化研究

    Institute of Scientific and Technical Information of China (English)

    魏庆朝; 尹国栋; 时瑾; 来琳

    2015-01-01

    Research purposes:With numerous railway lines laid in the yard,high -speed railway station should not only meet the operation requirements of train to pass in high speed,but also satisfy the demand of high -speed train to arrival,departure and turn -back in station yard.For the influence of speed reduction of train and station arrangement, radius of curve on arrival -departure line is much less than that of curve on main line,and parameter selection of lines connecting main line and arrival -departure line affects the travel quality of train directly.Referring to existing researches,and based on the dynamic theory and wheel -rail contact mode,dynamic analysis model was established, considering the running conditions of train between the main line and the arrival -departure line in high -speed railway station yard.Using the established model,effects on travelling safety and stability of train aroused by length variation of intermediate straight line and transition line connecting turnout on main line and curve on arrival -departure line behind turnout were calculated.Accordingly,theoretical basis is provided for the parameter optimization of lines connecting arrival -departure line and main line in high -speed railway station yard. Research conclusions:Based on related researches on the matching relation of superelevation and transition curve length with circular curve radius,required calculation parameters were selected,and calculations on the relation between travelling quality of train and parameter variation of connection lines between main line and arrival -departure line indicate that:(1 )To meet the demand of traveling stability,intermediate straight line with length not less than 9 m was proposed to be set to connect turnout on main line and curve on arrival -departure line in high -speed railway station yard.(2)The increase of transition curve length has rarely influence on easing vehicle vibration on circular curve as the length of transition curve

  16. Structural relaxation and thermal conductivity of high-pressure formed, high-density di-n-butyl phthalate glass and pressure induced departures from equilibrium state

    Science.gov (United States)

    Johari, G. P.; Andersson, Ove

    2017-06-01

    We report a study of structural relaxation of high-density glasses of di-n-butyl phthalate (DBP) by measuring thermal conductivity, κ, under conditions of pressure and temperature (p,T) designed to modify both the vibrational and configurational states of a glass. Various high-density glassy states of DBP were formed by (i) cooling the liquid under a fixed high p and partially depressurizing the glass, (ii) isothermal annealing of the depressurized glass, and (iii) pressurizing the glass formed by cooling the liquid under low p. At a given low p, κ of the glass formed by cooling under high p is higher than that of the glass formed by cooling under low p, and the difference increases as glass formation p is increased. κ of the glass formed under 1 GPa is ˜20% higher at ambient p than κ of the glass formed at ambient p. On heating at low p, κ decreases until the glass to liquid transition range is reached. This is the opposite of the increase in κ observed when a glass formed under a certain p is heated under the same p. At a given high p, κ of the low-density glass formed by cooling at low p is lower than that of the high-density glass formed by cooling at that high p. On heating at high p, κ increases until the glass to liquid transition range is reached. The effects observed are due to a thermally assisted approach toward equilibrium at p different from the glass formation p. In all cases, the density, enthalpy, and entropy would change until the glasses become metastable liquids at a fixed p, thus qualitatively relating κ to variation in these properties.

  17. Ultraprecision machining of steep aspheric parts with large sagittal height

    Science.gov (United States)

    Mu, Lin; Zhao, Rui; Xin, Qiming

    2009-05-01

    Problems occurred during machining steep aspheric parts with large sagittal height on double-spindle diamond turning machine are presented and the main reasons of the problems are described. And methods of solving these problems are also suggested. When we machine steep aspheric parts with large sagittal height on a 2 axis diamond turning machine, we have such problems as difficult control of part edge accuracy, poor roughness and rapid wear of the cutting tool. The main reasons for these problems lie in: 1) Measurement. To make accurate measurements, the measurement range of the profilometer must fall within the sagittal heights of the aspheric parts, and the measurement angle must also meet the requirements, an insufficient measurement angle, for example, will have a big impact on the measurement and fabrication accuracy of such parts; and 2) Machine and tool, firstly, the diamond cutting tool will suffer a very big force when turning the edge section, resulting in bigger micro-vibration in the tool and tool post, thus affecting the part accuracy and surface roughness. Secondly, the machine itself has location errors in axes X and Z during the processing, leading to the severest destruction in the steep section of the aspheric part by their resultant force. Lastly, anisotropy of diamond cutting tool hardness. The indentation hardness of the diamond is maximum in the direction of of face (100) and the front clearance has the best strength at tool point in the direction of . When cutting a steep aspheric part with large sagittal height, a bigger included angle of the diamond tool point arc will be used, and there will be a more deviation from the lattice direction. So the tool hardness is consistently decreased, resulting in a rapid wear of the cutting tool when turning the steep section of the aspheric part, thus the accuracy and roughness in machining an aspheric part become more difficult to control. The paper is concluded with the solutions of turning steep

  18. Refractive outcomes of an advanced aspherically optimized profile for myopia corrections by LASIK: a retrospective comparison with the standard aspherically optimized profile

    Directory of Open Access Journals (Sweden)

    Meyer B

    2015-02-01

    Full Text Available Bertram Meyer,1 Georg Sluyterman van Langeweyde,2 Matthias Wottke2 1Augencentrum Köln, Cologne, Germany; 2Carl Zeiss Meditec AG, Jena, Germany Purpose: A retrospective comparison of refractive outcomes of a new, aspherically optimized profile with an enhanced energy correction feature (Triple-A and the conventionally used aspherically optimized profile (ASA, or aberration smart ablation for correction of low-to-high myopia.Setting: Augen-OP-Centrum, Cologne, GermanyDesign: Retrospective nonrandomized comparative studyMethods: A central database at the Augen-OP-Centrum was used to gather retrospective data for low-to-high myopia (up to -10 D. One hundred and seven eyes (56 patients were treated with the ASA profile, and 79 eyes (46 patients were treated with the Triple-A profile. Postoperative outcomes were evaluated at 1 month, 3 months, 6 months, and 1 year follow-up time points.Results: The Triple-A profile showed better predictability indicated by a significantly lower standard deviation of residuals (0.32–0.34 vs 0.36–0.44, Triple-A vs ASA in the 6-month to 1-year period. The Triple-A group had better stability across all time intervals and achieved better postoperative astigmatism improvements with significantly lower scatter. This group achieved better safety at 1 year, with 100% of eyes showing no change or gain in Snellen lines, compared with 97% in the ASA group. A better safety index was observed for the Triple-A group at later time points. The Triple-A group had a better efficacy index and a higher percentage of eyes with an uncorrected Snellen visual acuity of 20/20 or greater at all investigated follow-up time points.Conclusion: The new aspherically optimized Triple-A profile can safely and effectively correct low-to-high myopia. It has demonstrated superiority over the ASA profile in most refractive outcomes. Keywords: Triple-A, wavefront measurements, corneal aberrations, corneal asphericity, ablation profile

  19. Computer Controlled Polishing of the Off-axis Aspheric Mirrors

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the manufacturing and testing procedures to make large off-axis aspherical mirrors are presented. The difficulties in polishing and testing for both circular-aperture and rectangular-aperture mirrors are previewed, and a possible solution is given. The two mirrors have been polished by means of CCOS, and the final accuracy is 25nm rms for 770mm×210mm rectangular mirror and 20nm rms for φ600mm circular mirror. These results just meet the optical tolerances specified by the designer, and the manufacturing and testing procedures presented here show good ability to make the large off-axis aspherical mirrors.

  20. 49 CFR 236.587 - Departure test.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Departure test. 236.587 Section 236.587..., Train Control and Cab Signal Systems Inspection and Tests; Locomotive § 236.587 Departure test. (a) The...: (1) Operation over track elements; (2) Operation over test circuit; (3) Use of portable...

  1. Student Engagement and Departure Intention: An Australian University Perspective

    Science.gov (United States)

    Jackling, Beverley; Natoli, Riccardo

    2011-01-01

    This study addresses the departure intentions of an Australian university business student cohort that is characterised by high levels of diversity in pre-entry attributes. The study investigates the level of student engagement using the academic and social integration components of the Student Engagement Questionnaire (SEQ) based on Tinto's model…

  2. Off-Axis Aspheric Surfacing Using Sub-Aperture Tools

    Science.gov (United States)

    Feng, Yunpeng; Qiao, Xiaoyan; Cheng, Haobo; Tam, Hon-Yuen

    2013-10-01

    The off-axis aspheric surface used in modern optical systems widely can obtain nearly perfect quality, realize both small packet-size and low-mass, and avoid the central obscuration. But it is difficult to fabricate because of asymmetry. There are some key technologies during the testing and fabrication of off-axis asphere. In this article, we proposed a method of the best fit sphere based on non-negative minimized removal criterion. And a measured data fitting algorithm was presented to estimate the geometry parameters of off-axis aspheric surface. Then an off-axis mirror was fabricated, and the interferometrically measured data was corrected to eliminate the distortion introduced by null compensator in every run. Finally, the surface error of off-axis mirror reduced to pv = 0.372λ, rms = 0.046λ, the surface roughness reached 0.72 nm. These methods mentioned in the article are suitable for off-axis aspheric optics.

  3. Research on the processing technology of medium-caliber aspheric lens in the optoelectronic integrated test system

    Science.gov (United States)

    Liu, Dan; Yu, Xin-ying; Wang, Wei

    2016-10-01

    In the optoelectronic integrated test system, surface profile and finish of the optical element are put forward higher request. Taking an aspherical quartz glass lens with a diameter of 200mm as example, taking Preston hypothesis as the theoretical basis, analyze the influence of surface quality of various process parameters, including the workpiece and the tool axis spindle speed, wheel type, concentration polishing, polishing mold species, dwell time, polishing pressure and other parameters. Using CNC method for the surface profile and surface quality of the lens were investigated. Taking profilometer measurement results as a guide, by testing and simulation analysis, process parameters were improved constantly in the process of manufacturing. Mid and high frequency error were trimmed and improved so that the surface form gradually converged to the required accuracy. The experimental results show that the final accuracy of the surface is less than 2µm and the surface finish is, which fulfils the accuracy requirement of aspherical focusing lens in optical system.

  4. The Simulation and Optimization of Aspheric Plastic Lens Injection Molding

    Institute of Scientific and Technical Information of China (English)

    WEN Jialing; WEN Pengfei

    2005-01-01

    For the purpose of reducing the volumetric shrinkage and volumetric shrinkage variation, the process in injection molding of aspheric plastic lens was simulated, and several process parameters which include holding pressure, melt temperature, mold temperature, fill time, holding pressure time and cooling time were optimized by using an orthogonal experimental design method. Finally, the optimum process parameters and the influence degree of process parameters on the average volumetric shrinkage and the volumetric shrinkage variation are obtained.

  5. THE BLOOD PRESSURE AMONG HIGH RISK PILGRIMS OF KLOTER 30 BEKASI, YEAR 2003 BEFORE DEPARTURE IN INDONESIA AND AFTER UMRAH IN MECCA

    OpenAIRE

    Betty Roosihermiatie; Sarwanto Sarwanto; Siswanto Siswanto

    2012-01-01

    The main cause of mortality among Indonesian pilgrims was circulatory diseases. The death was common among old pilgrims, especially due to heart failure. It is known that hypertension is one of the causes of heart failure The study aimed to determine blood pressures among high risk pilgrims after umrah in Mecca, Saudi Arabia and blood pressure in Indonesia with influencing factors: sex, body mass index, accommodation room density, and number of condition/diseases.It was an observational study...

  6. THE BLOOD PRESSURE AMONG HIGH RISK PILGRIMS OF KLOTER 30 BEKASI, YEAR 2003 BEFORE DEPARTURE IN INDONESIA AND AFTER UMRAH IN MECCA

    Directory of Open Access Journals (Sweden)

    Betty Roosihermiatie

    2012-11-01

    Full Text Available The main cause of mortality among Indonesian pilgrims was circulatory diseases. The death was common among old pilgrims, especially due to heart failure. It is known that hypertension is one of the causes of heart failure The study aimed to determine blood pressures among high risk pilgrims after umrah in Mecca, Saudi Arabia and blood pressure in Indonesia with influencing factors: sex, body mass index, accommodation room density, and number of condition/diseases.It was an observational study. Twenty eight high risk pilgrims of kelompok terbang (kloter or flight group 30 JKS year 2003 were voluntarily participated in the study. The blood pressure of the respondents was measured at sitting position. Mean differences of systolic and diastolic blood pressure in Indonesia and after umrah was compared by paired t-test. Systolic blood pressure in Indonesia after umrah, by controlling confounding variables was analyzed by linear regression model. The systolic blood pressure of respondents after umrah tended to decrease to 0.43 mm Hg in comparison to 1 mmHg increase on examination in Indonesia, at number of conditions/diseases to be constant. It is likely that the psychological sincerity (ikhlas has influenced the decrease of sympathetic intervations system in brainstem for blood pressure to lower of systolic blood pressure. Meanwhile, the systolic blood pressure after umrah tended to increase to 11.94 mmHg for a number of conditions/diseases to be constant. The pilgrimage activities is hard, especially in surrounding higher climate at the average of 39• C. So pilgrims with the condition as old people or having diseases influenced the systolic blood pressure. The peripheral vasoconstriction possibly caused increase systolic blood pressure. Pilgrimage is a hard physical activity, more over for high risk pilgrims. Hence, monitoring pilgrim health conditions, especially the high risk pilgnms, should be conducted by kloter health workers, like to control

  7. FEM analysis of hot-pressing process of aspheric glass P-SK57 lens

    Science.gov (United States)

    Zhu, Yongjian; Na, Jingxin; Wang, Yu; Li, Anhu; Zhi, Yanan; Fan, Yufeng

    2013-09-01

    Lens molding has become the promising technique to conduct mass produce of aspheric glass lens. It overcomes some disadvantages of traditional grinding or turning methods, such as high cost, low efficiency, unstable accuracy, and so on. Up to now, the lens molding process has been looked on as one of the reliable methods in fabrication of aspheric glass lens. However, in real production, one has found that it's hard to control the molding parameters, e.g. molding temperature, molding period, molding speed and pressing pressure, etc. Therefore it's necessary to develop the specific molding processes for a certain glass material. In this paper, SCHOTT P-SK57 is adopted to carry out the lens molding analysis in order to achieve the relative processing parameters. The molding cases are analyzed based on three different temperatures of 510°C, 520°C, and 530°C, higher than transition point 493°C of P-SK57. Through continuous heating and pressing simulation, the results show that the best pressing temperature could be about 530°C, at which the residual stress is only 5.22MPa (with the molding speed of 0.1mm/s).

  8. Mechanically tunable aspheric lenses via additive manufacture of hanging elastomeric droplets for microscopic applications

    Science.gov (United States)

    Fuh, Yiin-Kuen; Chen, Pin-Wen; Lai, Zheng-Hong

    2016-07-01

    Mechanically deformable lenses with dynamically tunable focal lengths have been developed in this work. The fabricated five types of aspheric polydimethylsiloxane (PDMS) lenses presented here have an initial focal length of 7.0, 7.8, 9.0, 10.0 and 10.2 mm. Incorporating two modes of operation in biconvex and concave-convex configurations, the focal lengths can be tuned dynamically as 5.2-10.2, 5.5-9.9, 6.6-11.9, 6.1-13.5 and 6.6-13.5 mm respectively. Additive manufacturing was utilized to fabricate these five types of aspheric lenses (APLs) via sequential layering of PDMS materials. Complex structures with three-dimensional features and shorter focal lengths can be successfully produced by repeatedly depositing, inverting and curing controlled PDMS volume onto previously cured PDMS droplets. From our experiments, we empirically found a direct dependence of the focal length of the lenses with the amount (volume) of deposited PDMS droplets. This new mouldless, low-cost, and flexible lens fabrication method is able to transform an ordinary commercial smartphone camera into a low-cost portable microscope. A few microscopic features can be readily visualized, such as wrinkles of ladybird pupa and printed circuit board. The fabrication technique by successively applying hanging droplet and facile mechanical focal-length-tuning set-up can be easily adopted in the development of high-performance optical lenses.

  9. Precision Departure Release Capability (PDRC) Final Report

    Science.gov (United States)

    Engelland, Shawn A.; Capps, Richard; Day, Kevin Brian; Kistler, Matthew Stephen; Gaither, Frank; Juro, Greg

    2013-01-01

    After takeoff, aircraft must merge into en route (Center) airspace traffic flows that may be subject to constraints that create localized demand/capacity imbalances. When demand exceeds capacity, Traffic Management Coordinators (TMCs) and Frontline Managers (FLMs) often use tactical departure scheduling to manage the flow of departures into the constrained Center traffic flow. Tactical departure scheduling usually involves a Call for Release (CFR) procedure wherein the Tower must call the Center to coordinate a release time prior to allowing the flight to depart. In present-day operations release times are computed by the Center Traffic Management Advisor (TMA) decision support tool, based upon manual estimates of aircraft ready time verbally communicated from the Tower to the Center. The TMA-computed release time is verbally communicated from the Center back to the Tower where it is relayed to the Local controller as a release window that is typically three minutes wide. The Local controller will manage the departure to meet the coordinated release time window. Manual ready time prediction and verbal release time coordination are labor intensive and prone to inaccuracy. Also, use of release time windows adds uncertainty to the tactical departure process. Analysis of more than one million flights from January 2011 indicates that a significant number of tactically scheduled aircraft missed their en route slot due to ready time prediction uncertainty. Uncertainty in ready time estimates may result in missed opportunities to merge into constrained en route flows and lead to lost throughput. Next Generation Air Transportation System plans call for development of Tower automation systems capable of computing surface trajectory-based ready time estimates. NASA has developed the Precision Departure Release Capability (PDRC) concept that improves tactical departure scheduling by automatically communicating surface trajectory-based ready time predictions and departure

  10. Precision Departure Release Capability (PDRC) Technology Description

    Science.gov (United States)

    Engelland, Shawn A.; Capps, Richard; Day, Kevin; Robinson, Corissia; Null, Jody R.

    2013-01-01

    After takeoff, aircraft must merge into en route (Center) airspace traffic flows which may be subject to constraints that create localized demand-capacity imbalances. When demand exceeds capacity, Traffic Management Coordinators (TMCs) often use tactical departure scheduling to manage the flow of departures into the constrained Center traffic flow. Tactical departure scheduling usually involves use of a Call for Release (CFR) procedure wherein the Tower must call the Center TMC to coordinate a release time prior to allowing the flight to depart. In present-day operations release times are computed by the Center Traffic Management Advisor (TMA) decision support tool based upon manual estimates of aircraft ready time verbally communicated from the Tower to the Center. The TMA-computed release is verbally communicated from the Center back to the Tower where it is relayed to the Local controller as a release window that is typically three minutes wide. The Local controller will manage the departure to meet the coordinated release time window. Manual ready time prediction and verbal release time coordination are labor intensive and prone to inaccuracy. Also, use of release time windows adds uncertainty to the tactical departure process. Analysis of more than one million flights from January 2011 indicates that a significant number of tactically scheduled aircraft missed their en route slot due to ready time prediction uncertainty. Uncertainty in ready time estimates may result in missed opportunities to merge into constrained en route flows and lead to lost throughput. Next Generation Air Transportation System (NextGen) plans call for development of Tower automation systems capable of computing surface trajectory-based ready time estimates. NASA has developed the Precision Departure Release Capability (PDRC) concept that uses this technology to improve tactical departure scheduling by automatically communicating surface trajectory-based ready time predictions to the

  11. Application of the NANOMEFOS non-contact measurement machine in asphere and freeform optics production

    NARCIS (Netherlands)

    Henselmans, R.; Gubbels, G.P.H.; Drunen, C. van

    2010-01-01

    The NANOMEFOS machine is capable of fast, non-contact and universal measurement of aspheres and freeforms, up to ø500 mm with a measurement uncertainty below 30 nm (2σ). It is now being applied in asphere and freeform production at TNO.

  12. Clinical comparison of the optical performance of aspheric and spherical intraocular lenses

    NARCIS (Netherlands)

    van Gaalen, Kim W.; Koopmans, Steven A.; Jansonius, Nomdo M.; Kooijman, Aart C.

    2010-01-01

    PURPOSE: To compare the optical performance of aspheric Tecnis ZA9003 and spherical Sensar AR40e intraocular lenses (IOLs). SETTING: Laboratory of Experimental Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. METHODS: An aspheric IOL was implan

  13. 高阶像差及散射光对非球面IOL眼视网膜成像质量的影响%Effect of high-order aberrations and scattered light on visual quality in pseudophakic eyes with aspheric monofocal IOLs

    Institute of Scientific and Technical Information of China (English)

    马瑶; 马忠旭; 高原; 孙龙格

    2016-01-01

    .05;r=0.319 ~0.598,均P<0.01).结论 非球面IOL植入眼的高阶像差及散射光可能是术眼客观视网膜成像质量下降的主要影响因素,晶状体高阶像差对全眼高阶像差的影响更大.%Background High order aberrations and scattered light may be the main influencing factors of visual quality after phacoemulsification combined the aspherical IOL implantation.However,the study on objectively assessing the impact of them is little.Objective This study was to assess the impact of high order aberrations and scattered light on visual quality after phacoemulsification combined the aspherical IOL implantation.Methods A series cases-observational study was performed.Sixty-seven eyes of 53 patients who finished phacoemulsification and aspherical IOL implantation for at least 3 months in Tianjin Eye Hospital from February to August 2014 were enrolled.The root mean square (RMS) of total aberrations and high order aberrations was measured under the 4 mm pupil diameter with i-Trace aberrometer,including general high order aberrations,spherical aberrations,coma,and trefoil of entire eye,cornea and internal optics.The correlations between ocular aberrations and corneal or internal optic aberrations were analyzed.Objective scatter index (OSI) and objective visual quality parameters were measured,including MTF cut off frequency (MTF cut off),strehl ratio (SR) and OQAS values (100% OV,20% OV,9% OV) with OQAS Ⅱ,and the correlations between the objective visual quality parameters and OSI,ocular aberrations,corneal aberrations or internal optic aberrations were analyzed.In addition,the correlations between OSI and ocular,corneal or internal optic aberrations were evaluated.Writen informed censent was obtained from each patient before entering the study.Results Ocular aberrations were significantly positively correlated with corneal or internal optic aberrations (r=0.255-0.586,all at P<0.05;r=0.582-0.907,all at P<0.01),and the associations between

  14. Optimizing departure times in vehicle routes

    NARCIS (Netherlands)

    Kok, A.L.; Hans, E.W.; Schutten, J.M.J.

    2011-01-01

    Most solution methods for the vehicle routing problem with time windows (VRPTW) develop routes from the earliest feasible departure time. In practice, however, temporary traffic congestion make such solutions non-optimal with respect to minimizing the total duty time. Furthermore, the VRPTW does not

  15. Optimizing departure times in vehicle routes

    NARCIS (Netherlands)

    Kok, A.L.; Hans, E.W.; Schutten, J.M.J.

    2008-01-01

    Most solution methods for the vehicle routing problem with time windows (VRPTW) develop routes from the earliest feasible departure time. However, in practice, temporal traffic congestions make that such solutions are not optimal with respect to minimizing the total duty time. Furthermore, VRPTW sol

  16. 20 CFR 655.35 - Required departure.

    Science.gov (United States)

    2010-04-01

    ... Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR TEMPORARY EMPLOYMENT OF... Temporary Employment in Occupations Other Than Agriculture or Registered Nursing in the United States (H-2B...) Notice to worker. Upon establishment of a pilot program by DHS for registration of departure,...

  17. Error analysis and system optimization of non-null aspheric testing system

    Science.gov (United States)

    Luo, Yongjie; Yang, Yongying; Liu, Dong; Tian, Chao; Zhuo, Yongmo

    2010-10-01

    A non-null aspheric testing system, which employs partial null lens (PNL for short) and reverse iterative optimization reconstruction (ROR for short) technique, is proposed in this paper. Based on system modeling in ray tracing software, the parameter of each optical element is optimized and this makes system modeling more precise. Systematic error of non-null aspheric testing system is analyzed and can be categorized into two types, the error due to surface parameters of PNL in the system modeling and the rest from non-null interferometer by the approach of error storage subtraction. Experimental results show that, after systematic error is removed from testing result of non-null aspheric testing system, the aspheric surface is precisely reconstructed by ROR technique and the consideration of systematic error greatly increase the test accuracy of non-null aspheric testing system.

  18. Solving surface parameters of conic asphere mirror based on computer simulation

    Science.gov (United States)

    Huang, Chuan-ke; Wu, Yong-qian; Fan, Bin; Lei, Bai-ping

    2016-09-01

    Radius of curvature R and conic constant k are important parameters of aspheres.Null testing or CGH are usually used to evaluate the processing quality of aspheric mirrors in fabricating process . When the null compensator emerges a problem, additional method to ensure the accuracy of paraxial radius of curvature and conic constant is required. Based on the equation of conic aspheric, the computing model from which the paraxial radius of curvature R and conic constant k can be obtained was established, and a set of solving algorithm using singular value decomposition (SVD) method was derived. The simulating result of a 1800mm aspheric mirror is presented and the solving precision reaches R=6120+/-0.026mm, k=-1.0194+/-0.0008, thus the supplement to null testing of aspheric mirror is achieved effectively .

  19. GANAS: A HYBRID ANASTIGMATIC ASPHERICAL PRIME-FOCUS CORRECTOR

    Directory of Open Access Journals (Sweden)

    F. Della Prugna

    2009-01-01

    Full Text Available The Cassegrain-Coud 1 meter Car to the focal plane of the primary f/5 l Zeiss telescope at the Venezuelan National Astronomical Observatory uses six optical elements. Removal of the secondary convex mirror gives accessspheroidal mirror, but spherical aberration, coma, astigmatism and eld curvature severely hamper its imaging capabilities. In order to carry out prime-focus imaging, we designed and manufactured a corrector group, called GAnAs, to minimize these aberrations over a circular eld of 300. The corrector group is a hybrid con guration with two thin aspherical 4th-order plates and a meniscus lens.

  20. Intercomparison study and optical asphericity measurements of small ice particles in the CERN CLOUD experiment

    Directory of Open Access Journals (Sweden)

    L. Nichman

    2017-09-01

    Full Text Available Optical probes are frequently used for the detection of microphysical cloud particle properties such as liquid and ice phase, size and morphology. These properties can eventually influence the angular light scattering properties of cirrus clouds as well as the growth and accretion mechanisms of single cloud particles. In this study we compare four commonly used optical probes to examine their response to small cloud particles of different phase and asphericity. Cloud simulation experiments were conducted at the Cosmics Leaving OUtdoor Droplets (CLOUD chamber at European Organisation for Nuclear Research (CERN. The chamber was operated in a series of multi-step adiabatic expansions to produce growth and sublimation of ice particles at super- and subsaturated ice conditions and for initial temperatures of −30, −40 and −50 °C. The experiments were performed for ice cloud formation via homogeneous ice nucleation. We report the optical observations of small ice particles in deep convection and in situ cirrus simulations. Ice crystal asphericity deduced from measurements of spatially resolved single particle light scattering patterns by the Particle Phase Discriminator mark 2 (PPD-2K, Karlsruhe edition were compared with Cloud and Aerosol Spectrometer with Polarisation (CASPOL measurements and image roundness captured by the 3View Cloud Particle Imager (3V-CPI. Averaged path light scattering properties of the simulated ice clouds were measured using the Scattering Intensity Measurements for the Optical detectioN of icE (SIMONE and single particle scattering properties were measured by the CASPOL. We show the ambiguity of several optical measurements in ice fraction determination of homogeneously frozen ice in the case where sublimating quasi-spherical ice particles are present. Moreover, most of the instruments have difficulties of producing reliable ice fraction if small aspherical ice particles are present, and all of the instruments cannot

  1. Error compensation in computer generated hologram-based form testing of aspheres.

    Science.gov (United States)

    Stuerwald, Stephan

    2014-12-10

    Computer-generated holograms (CGHs) are used relatively often to test aspheric surfaces in the case of medium and high lot sizes. Until now differently modified measurement setups for optical form testing interferometry have been presented, like subaperture stitching interferometry and scanning interferometry. In contrast, for testing low to medium lot sizes in research and development, a variety of other tactile and nontactile measurement methods have been developed. In the case of CGH-based interferometric form testing, measurement deviations in the region of several tens of nanometers typically occur. Deviations arise especially due to a nonperfect alignment of the asphere relative to the testing wavefront. Therefore, the null test is user- and adjustment-dependent, which results in insufficient repeatability and reproducibility of the form errors. When adjusting a CGH, an operator usually performs a minimization of the spatial frequency of the fringe pattern. An adjustment to the ideal position, however, often cannot be performed with sufficient precision by the operator as the position of minimum spatial fringe density is often not unique, which also depends on the asphere. Thus, the scientific and technical objectives of this paper comprise the development of a simulation-based approach to explain and quantify typical experimental errors due to misalignment of the specimen toward a CGH in an optical form testing measurement system. A further step is the programming of an iterative method to realize a virtual optimized realignment of the system on the basis of Zernike polynomial decomposition, which should allow for the calculation of the measured form for an ideal alignment and thus a careful subtraction of a typical alignment-based form error. To validate the simulation-based findings, a series of systematic experiments is performed with a recently developed hexapod positioning system in order to allow an exact and reproducible positioning of the optical CGH

  2. Intercomparison study and optical asphericity measurements of small ice particles in the CERN CLOUD experiment

    Science.gov (United States)

    Nichman, Leonid; Järvinen, Emma; Dorsey, James; Connolly, Paul; Duplissy, Jonathan; Fuchs, Claudia; Ignatius, Karoliina; Sengupta, Kamalika; Stratmann, Frank; Möhler, Ottmar; Schnaiter, Martin; Gallagher, Martin

    2017-09-01

    Optical probes are frequently used for the detection of microphysical cloud particle properties such as liquid and ice phase, size and morphology. These properties can eventually influence the angular light scattering properties of cirrus clouds as well as the growth and accretion mechanisms of single cloud particles. In this study we compare four commonly used optical probes to examine their response to small cloud particles of different phase and asphericity. Cloud simulation experiments were conducted at the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at European Organisation for Nuclear Research (CERN). The chamber was operated in a series of multi-step adiabatic expansions to produce growth and sublimation of ice particles at super- and subsaturated ice conditions and for initial temperatures of -30, -40 and -50 °C. The experiments were performed for ice cloud formation via homogeneous ice nucleation. We report the optical observations of small ice particles in deep convection and in situ cirrus simulations. Ice crystal asphericity deduced from measurements of spatially resolved single particle light scattering patterns by the Particle Phase Discriminator mark 2 (PPD-2K, Karlsruhe edition) were compared with Cloud and Aerosol Spectrometer with Polarisation (CASPOL) measurements and image roundness captured by the 3View Cloud Particle Imager (3V-CPI). Averaged path light scattering properties of the simulated ice clouds were measured using the Scattering Intensity Measurements for the Optical detectioN of icE (SIMONE) and single particle scattering properties were measured by the CASPOL. We show the ambiguity of several optical measurements in ice fraction determination of homogeneously frozen ice in the case where sublimating quasi-spherical ice particles are present. Moreover, most of the instruments have difficulties of producing reliable ice fraction if small aspherical ice particles are present, and all of the instruments cannot separate perfectly

  3. Understanding the "personological" basis of employee withdrawal: the influence of affective disposition on employee tardiness, early departure, and absenteeism.

    Science.gov (United States)

    Iverson, R D; Deery, S J

    2001-10-01

    This study investigated the impact of positive affectivity (PA) and negative affectivity (NA) on employee tardiness, early departure, and absenteeism, controlling for demographic, job-related, and environmental variables. The 3 temporary withdrawal measures were collected from organizational records in the 12 months following the survey. The LISREL analysis was based on a sample of 362 blue-collar employees from a multinational automotive manufacturer. The results indicate that individuals high in PA were associated with increased tardiness and early departure but decreased absenteeism. Individuals high in NA were associated with increased early departure. In terms of moderator effects, job satisfaction had a significant negative impact for individuals low in PA in predicting tardiness and early departure, whereas job satisfaction displayed a significant negative relationship with early departure for individuals high in NA. Implications of the findings are discussed.

  4. Systematic uncertainties from halo asphericity in dark matter searches

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, Nicolás [ICTP South American Institute for Fundamental Research, Instituto de Física Teórica, Universidade Estadual Paulista, São Paulo (Brazil); Forero-Romero, Jaime E. [Departamento de Física, Universidad de los Andes, Cra. 1 No. 18A-10, Edificio Ip, Bogotá (Colombia); Garani, Raghuveer [Bethe Center for Theoretical Physics and Physikalisches Institut, Universität Bonn, Nußallee 12, D-53115 Bonn,Germany (Germany); Palomares-Ruiz, Sergio, E-mail: nicolas@ift.unesp.br, E-mail: je.forero@uniandes.edu.co, E-mail: garani@th.physik.uni-bonn.de, E-mail: sergio.palomares.ruiz@ific.uv.es [Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València, Apartado de Correos 22085, E-46071, València (Spain)

    2014-09-01

    Although commonly assumed to be spherical, dark matter halos are predicted to be non-spherical by N-body simulations and their asphericity has a potential impact on the systematic uncertainties in dark matter searches. The evaluation of these uncertainties is the main aim of this work, where we study the impact of aspherical dark matter density distributions in Milky-Way-like halos on direct and indirect searches. Using data from the large N-body cosmological simulation Bolshoi, we perform a statistical analysis and quantify the systematic uncertainties on the determination of local dark matter density and the so-called J factors for dark matter annihilations and decays from the galactic center. We find that, due to our ignorance about the extent of the non-sphericity of the Milky Way dark matter halo, systematic uncertainties can be as large as 35%, within the 95% most probable region, for a spherically averaged value for the local density of 0.3-0.4 GeV/cm {sup 3}. Similarly, systematic uncertainties on the J factors evaluated around the galactic center can be as large as 10% and 15%, within the 95% most probable region, for dark matter annihilations and decays, respectively.

  5. From AGB Stars to Aspherical Planetary Nebulae - An Observational Perspective

    Science.gov (United States)

    Sahai, R.

    2014-04-01

    Most stars that leave the main sequence in a Hubble time will end their lives, evolving through the Asymptotic Giant Branch (AGB), Preplanetary Nebula (PPN) and Planetary Nebula (PN) evolutionary phases. The heavy mass loss which occurs during the AGB phase is important across astrophysics, dramatically changing the course of stellar evolution, dominantly contributing to the dust content of the interstellar medium, and influencing its chemical composition. Yet stellar evolution from the beginning of the AGB phase to the PN phase remains poorly understood, especially the dramatic transformation that occurs in the morphology of the mass-ejecta as AGB stars and their round circumstellar envelopes evolve into mostly PNe, the majority of which deviate strongly from spherical symmetry. In this review, I describe the observations, spanning the wavelength range from X-rays to millimeter wavelengths, that have contributed to our current understanding of the physical processes responsible for the formation of aspherical PNe. I conclude by a brief summary of future observations using current and upcoming facilities such as HST, Chandra, ALMA and JWST that can help in addressing the major unsolved problems in the study of aspherical PNe.

  6. Non-rotational aspherical models of the human optical system

    Science.gov (United States)

    Giovanzana, S.; Kasprzak, H. T.; Pałucki, B.; Ţălu, Ş.

    2013-12-01

    The aim of this work was to define three-dimensional (3D) non-rotational aspherical parametric models for the human cornea and lens using computational geometry and CAD representations. The hyperbolic cosine based function is used for the cornea and a parametric model is used for lens modeling. Data analysis and visualization of 3D non-rotational models were made using the Rhinoceros CAD software and MATLAB software was used for numeric computation. We combined, implemented, and evaluated these models with a 3D ray-tracing in order to fully analyze the human eye model. It was found that 3D non-rotational aspherical models for the human eye could be more accurately modeled and rendered for analysis with finite element method. The objective of this study is to present and analyze mathematical models of the cornea and lens and to highlight the potential of optical applications of the eye models containing astigmatic surfaces, which are more close to the real eye than spherosymmetric eye models.

  7. Integration of Tactical Departure Scheduling and Traffic Flow Management Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In the ATM Select topic area of Integrated Arrival, Departure and Surface (IADS) planning, this proposal addresses Tactical Departure Scheduling (TDS), which is a...

  8. Three-dimensional photoacoustic imaging system with a 4f aspherical acoustic lens

    Science.gov (United States)

    Jen, En; Lin, Hsintien; Chiang, Huihua Kenny

    2016-08-01

    Photoacoustic (PA) imaging is a modality for achieving high-contrast images of blood vessels or tumors. Most PA imaging systems use complex reconstruction algorithms under conventional linear array transducers. We introduced the optical simulating method to improve the acoustic lens design and obtain a PA imaging system with improved spatial revolution (a 0.5-mm point spread function and a lateral image resolution of more than 1 mm) is realized using a 4f aspherical acoustic lens. The acoustic lens approach improved the image resolution and enabled direct reconstruction of three-dimensional (3-D) PA images. The system demonstrated a lateral resolution of more than 1 mm, a field of view of 8.5 deg, and a depth of focus of 10 mm. The system displays great potential for developing a real-time 3-D PA camera system for biomedical ultrasound imaging applications.

  9. Development of Aspherical Active Gratings at NSRRC

    Science.gov (United States)

    Tseng, Tse-Chuan; Wang, Duan Jen; Perng, Shen-Yaw; Chen, Chien-Te; Lin, Chia-Jui; Kuan, Chien-Kuang; Ho, His-Chou; Wang, Jeremy; Fung, H. S.; Chang, Shuo-Hung

    2007-01-01

    An active grating based on a novel optical concept with bendable polynomial surface profile to reduce the coma and defocus aberrations had been designed and proved by the prototype testing. Due to the low glass transition temperature of the glue and the difference of thermal expansion coefficient between the 17-4 steel bender and silicon, the prototype distorted from flat polished condition when thermally de-blocked the polishing pitch. To improve the thermal deformation of the active grating in the polishing process, a new invar bender and high curing temperature glue were adapted to glue a silicon substrate on the bender. After some tests and manufacturer polishing, it showed acceptable conditions. In this paper we will present the design and preliminary tests of the invar active grating. Meanwhile, the design and analysis of a new 17-4 PH steel bender to be electro-less nickel plating and mechanical ruling for a new beamline will also be discussed.

  10. Spectroscopic evidence of large aspherical β-NAT particles involved in denitrification in the December 2011 Arctic stratosphere

    Science.gov (United States)

    Woiwode, Wolfgang; Höpfner, Michael; Bi, Lei; Pitts, Michael C.; Poole, Lamont R.; Oelhaf, Hermann; Molleker, Sergej; Borrmann, Stephan; Klingebiel, Marcus; Belyaev, Gennady; Ebersoldt, Andreas; Griessbach, Sabine; Grooß, Jens-Uwe; Gulde, Thomas; Krämer, Martina; Maucher, Guido; Piesch, Christof; Rolf, Christian; Sartorius, Christian; Spang, Reinhold; Orphal, Johannes

    2016-07-01

    We analyze polar stratospheric cloud (PSC) signatures in airborne MIPAS-STR (Michelson Interferometer for Passive Atmospheric Sounding - STRatospheric aircraft) observations in the spectral regions from 725 to 990 and 1150 to 1350 cm-1 under conditions suitable for the existence of nitric acid trihydrate (NAT) above northern Scandinavia on 11 December 2011. The high-resolution infrared limb emission spectra of MIPAS-STR show a characteristic "shoulder-like" signature in the spectral region around 820 cm-1, which is attributed to the ν2 symmetric deformation mode of NO3- in β-NAT. Using radiative transfer calculations involving Mie and T-Matrix methods, the spectral signatures of spherical and aspherical particles are simulated. The simulations are constrained using collocated in situ particle measurements. Simulations assuming highly aspherical spheroids with aspect ratios (AR) of 0.1 or 10.0 and a lognormal particle mode with a mode radius of 4.8 µm reproduce the observed spectra to a high degree. A smaller lognormal mode with a mode radius of 2.0 µm, which is also taken into account, plays only a minor role. Within the scenarios analyzed, the best overall agreement is found for elongated spheroids with AR = 0.1. Simulations of spherical particles and spheroids with AR = 0.5 and 2.0 return results very similar to each other and do not allow us to reproduce the signature around 820 cm-1. The observed "shoulder-like" signature is explained by the combination of the absorption/emission and scattering characteristics of large highly aspherical β-NAT particles. The size distribution supported by our results corresponds to ˜ 9 ppbv of gas-phase equivalent HNO3 at the flight altitude of ˜ 18.5 km. The results are compared with the size distributions derived from the in situ observations, a corresponding Chemical Lagrangian Model of the Stratosphere (CLaMS) simulation, and excess gas-phase HNO3 observed in a nitrification layer directly below the observed PSC. The

  11. Clinical observation of multifocal intraocular lens with aspheric astigmatism in cataract surgery

    Directory of Open Access Journals (Sweden)

    Xiao-Feng Wang

    2017-08-01

    Full Text Available AIM: By comparing the aspheric and multifocal Toric intraocular lens and the aspheric intraocular lens in cataract patients, to observe the patients' visual quality, to evaluate the patients' distance visual acuity, near visual acuity, Pseudo-accommodative power, residual astigmatism, the rotational stability of AcrySof IQ Toric Restor intraocular lens(IOLs, contrast the rate of off-distance glass, the rate of off-near glass and patient satisfaction after the implantation of AcrySof IQ Toric Restor IOL in the cataract patients with preexisting corneal astigmatism. METHODS:Carried out in 46 patients(48 eyeswith age-rated cataract who receiving phacoemulsification and implantation of artificial lens in our department during February 2014 to June 2016. All the cases were randomly divided into 2 groups: experimental group: 23 cases(24 eyes, AcrySof IQ ReSTOR Toric IOL was implanted after phacoemulsification; control group: 23 cases(24 eyes, AcrySof IQ was implanted. Uncorrected distance visual acuity(UCDVAand best corrected distance visual acuity(BCDVA, uncorrected near visual acuity(UCNVAand best-corrected near visual acuity(BCNVA, Pseudo-accommodative power, residual astigmatism, preoperative and postoperative corneal astigmatism, the rate of off-distance glass, the rate of off-near glass and patient satisfaction were measured at 6mo postoperatively follow-up. RESULTS: BCDVA and BCNVA were not statistically different between the two groups(PPPPPPPCONCLUSION:The results indicate that AcrySof IQ ReSTOR Toric IOLs may provide a better uncorrected distance visual acuity and uncorrected near visual acuity, which can significantly reduce preexisting corneal astigmatism in cataract surgery, improve spectacles independence for distance vision and spectacles independence for near vision, have a high patient satisfaction.

  12. Milking the spherical cow: on aspherical dynamics in spherical coordinates

    CERN Document Server

    Pontzen, Andrew; Teyssier, Romain; Governato, Fabio; Gualandris, Alessia; Roth, Nina; Devriendt, Julien

    2015-01-01

    Galaxies and the dark matter halos that host them are not spherically symmetric, yet spherical symmetry is a helpful simplifying approximation for idealised calculations and analysis of observational data. The assumption leads to an exact conservation of angular momentum for every particle, making the dynamics unrealistic. But how much does that inaccuracy matter in practice for analyses of stellar distribution functions, collisionless relaxation, or dark matter core-creation? We provide a general answer to this question for a wide class of aspherical systems; specifically, we consider distribution functions that are "maximally stable", i.e. that do not evolve at first order when external potentials (which arise from baryons, large scale tidal fields or infalling substructure) are applied. We show that a spherically-symmetric analysis of such systems gives rise to the false conclusion that the density of particles in phase space is ergodic (a function of energy alone). Using this idea we are able to demonstra...

  13. Critical phenomena in the aspherical gravitational collapse of radiation fluids

    CERN Document Server

    Baumgarte, Thomas W

    2015-01-01

    We study critical phenomena in the gravitational collapse of a radiation fluid. We perform numerical simulations in both spherical symmetry and axisymmetry, and observe critical scaling in both supercritical evolutions, which lead to the formation of a black hole, and subcritical evolutions, in which case the fluid disperses to infinity and leaves behind flat space. We identify the critical solution in spherically symmetric collapse, find evidence for its universality, and study the approach to this critical solution in the absence of spherical symmetry. For the cases that we consider, aspherical deviations from the spherically symmetric critical solution decay in damped oscillations in a manner that is consistent with the behavior found by Mart\\'in-Garc\\'ia and Gundlach in perturbative calculations. Our simulations are performed with an unconstrained evolution code, implemented in spherical polar coordinates, and adopting "moving-puncture" coordinates.

  14. Very large computer generated holograms for precision metrology of aspheric optical surfaces Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Both ground and space telescopes employ aspheric mirrors. A particular example is the X-ray telescope where primary and secondary mirrors have nearly cylindrical...

  15. Integration of Full-Spectrum Metrology and Polishing for Rapid Production of Large Aspheres Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design, build, and test a major new instrument capable of both measuring and polishing the surface of aspheric mirrors up to 1.2 meters in diameter,...

  16. Topological in-plane polarized piezo actuation for compact adaptive lenses with aspherical correction

    CERN Document Server

    Lemke, Florian; Wallrabe, Ulrike; Wapler, Matthias C

    2016-01-01

    In this contribution, we investigate the effects of using in-plane polarized piezo actuators with topological buckling displacement to drive glass-piezo composite membranes for adaptive lenses with aspherical control. We find that the effects on the focal power and aspherical tuning range are relatively small, whereas the tuning speed is improved significantly with a first resonance of 1 kHz for a 13 mm aperture lens.

  17. Topographic determination of corneal asphericity as a function of age, gender, and refractive error.

    Science.gov (United States)

    Yazdani, Negareh; Shahkarami, Leila; OstadiMoghaddam, Hadi; Ehsaei, Asieh

    2017-08-01

    The aim of the study is to evaluate corneal asphericity in three diameters of 5, 6, and 7 mm, and to assess the effect of age, refractive error, and gender on asphericity. The study included 500 healthy subjects with a mean ± SD age of 29.51 ± 11.53 years. All analyses were based on the right eyes of the patients. Topographic data were analyzed using Oculus Keratograph 4. Mean ± SD corneal asphericity values of the study population in 5, 6, and 7 mm diameters were -0.21 ± 0.11, -0.24 ± 0.10, and -0.27 ± 0.11, respectively. The anterior corneal surface asphericity showed no correlation with either age, gender, or refractive error. The corneal asphericity shows a tendency for an increase with diameter and asphericity does not have a significant correlation with any factors of age, gender, and refractive error.

  18. Optical beam-shaping design based on aspherical lenses for circularization collimation, and expansion of elliptical laser beams

    Science.gov (United States)

    Serkan, Mert; Kirkici, Hulya

    2008-01-01

    We present two optical system designs using aspherical lenses for beam circularization, collimation, and expansion of semiconductor lasers for possible application in lidar systems. Two different optical lens systems are investigated; namely, two aspherical lens and single aspherical lens systems. Software package programs of ZEMAX and MATLAB to simulate the optical designs are used. The beam reshaping results are presented for one specific laser beam output.

  19. 组合非球面太阳能聚光镜的光学设计%Optical design of build-up aspherical solar concentrating mirror

    Institute of Scientific and Technical Information of China (English)

    秦华; 冯东太; 葛硕硕; 王勇

    2014-01-01

    In this paper , a build-up aspherical solar concentrating mirror and its design method are presented . It is composed of 38 pieces of revolution surfaces , and each piece of revolution surface is the part of the as-pheric surface defined by a set of specific coefficients C,a2 ,a4 ,a6 ,a8 ,a10 .According to the even aspherical e-quation and the law of reflection in vector form , the relationship between the direction vectors of rays of light reflected from the inner wall of aspheric surface and the coefficients of an aspherical equation , C,a2 ,a4 ,a6 , a8 ,a10 , has been derived .By appropriately choosing these aspherical coefficients , namely, appropriately ad-justing an aspherical surface type , the reflected light beam can have specific direction vectors , which can make the sunbeams incident on an aspherical inner wall focus on a particular area and form a small spot .Each group of specific coefficients is obtained by using particle swarm optimization algorithm .The focusing effect of the solar concentrating mirror with the specific coefficients is demonstrated by using computer simulations and proved experimentally .The theoretical compression ratio for this concentrating mirror is 330∶1 .The focused spot can be used as a high temperature heat source and the concentrating mirror can be used in a solar heating device .%提出了一种组合非球面反射型太阳能聚光镜并给出了设计方法。聚光镜由38片非球面组成,每一片非球面都由一组特定系数C,a2,a4,a6,a8,a10的偶次非球面方程决定,是此特定非球面的一部分。根据非球面方程和光反射定律矢量形式,导出了非球面内壁上太阳反射光束的方向矢量与非球面系数C,a2,a4,a6,a8,a10的关系,适当地选择这些非球面系数,即适当地调整非球面面型,可以使太阳反射光束具有特定的方向矢量,使入射到非球面内壁上的太阳光束反射后全部聚焦在某一特定的区域

  20. Dynamics of aspherical dust grains in a cometary atmosphere: I. axially symmetric grains in a spherically symmetric atmosphere

    Science.gov (United States)

    Ivanovski, S. L.; Zakharov, V. V.; Della Corte, V.; Crifo, J.-F.; Rotundi, A.; Fulle, M.

    2017-01-01

    In-situ measurements of individual dust grain parameters in the immediate vicinity of a cometary nucleus are being carried by the Rosetta spacecraft at comet 67P/Churyumov-Gerasimenko. For the interpretations of these observational data, a model of dust grain motion as realistic as possible is requested. In particular, the results of the Stardust mission and analysis of samples of interplanetary dust have shown that these particles are highly aspherical, which should be taken into account in any credible model. The aim of the present work is to study the dynamics of ellipsoidal shape particles with various aspect ratios introduced in a spherically symmetric expanding gas flow and to reveal the possible differences in dynamics between spherical and aspherical particles. Their translational and rotational motion under influence of the gravity and of the aerodynamic force and torque is numerically integrated in a wide range of physical parameters values including those of comet 67P/Churyumov-Gerasimenko. The main distinctions of the dynamics of spherical and ellipsoidal particles are discussed. The aerodynamic characteristics of the ellipsoidal particles, and examples of their translational and rotational motion in the postulated gas flow are presented.

  1. Minimization of variation in volumetric shrinkage and deflection on injection molding of Bi-aspheric lens using numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bensingh, R. Joseph [Central Institute of Plastics Engineering and Technology, Chennai (India); Boopathy, S. Rajendra [College of Engineering, Anna University, Chennai (India); Jebaraj, C. [Vellore Institutes of Technology, Chennai (India)

    2016-11-15

    The profile of a bi-aspheric lens is such a way that the thickness narrows down from center to periphery (convex). Injection molding of these profiles has high shrinkage in localized areas, which results in internal voids or sink marks when the part gets cool down to room temperature. This paper deals with the influence of injection molding process parameters such as mold surface temperature, melt temperature, injection time, V/P Switch over by percentage volume filled, packing pressure, and packing duration on the volumetric shrinkage and deflection. The optimal molding parameters for minimum variation in volumetric shrinkage and deflection of bi-aspheric lens have been determined with the application of computer numerical simulation integrated with optimization. The real experimental work carried out with optimal molding parameters and found to have a shallow and steep surface profile accuracy of 0.14 and 1.57 mm, 21.38-45.66 and 12.28-26.90 μm, 41.56-157.33 and 41.56-157.33 nm towards Radii of curvatures (RoC), surface roughness (Ra) and waviness of the surface profiles (profile error Pt), respectively.

  2. Contrast sensitivity evaluation of aspheric and spherical intraocular lenses 2 years after implantation.

    Science.gov (United States)

    Caporossi, Aldo; Casprini, Fabrizio; Martone, Gianluca; Balestrazzi, Angelo; Tosi, Gian Marco; Ciompi, Leonardo

    2009-07-01

    To compare the quality of vision with aspheric and spherical intraocular lenses (IOLs) in pseudophakic patients after long-term follow-up. Two hundred eyes of 100 patients with bilateral cataracts were randomly assigned to receive spherical (Acrysof SN60AT [Alcon Laboratories Inc] or Sensar AR40e [Advanced Medical Optics Inc]) or aspheric IOLs (Acrysof SN60WF [Alcon] or Tecnis Z9000 [Advanced Medical Optics]). Ophthalmologic examination, including best spectacle-corrected visual acuity (BSCVA), pupil size, ocular dominance, contrast sensitivity under mesopic and photopic conditions, and wavefront analysis, was performed 2 months and 1 and 2 years after surgery. No statistically significant differences among the four groups in terms of age, pupil diameter, postoperative BSCVA, comeal spherical aberration, and posterior capsular opacification were noted. At all followup examinations, contrast sensitivity results showed no significant differences between the two aspheric IOLs at all spatial frequencies. Under photopic conditions, significant differences (P<.05) between spherical and aspheric IOLs were detected for spatial frequencies of 12 and 18 cycles per degree (cpd) at 2 months and 2 years and 12 cpd at 1 year. Under mesopic conditions, significant differences (P<.05) were detected between spherical and aspheric IOLs for all spatial frequencies at 2 months; all spatial frequencies except 18 cpd at 1 year; and spatial frequencies of 3, 12, and 18 cpd at 2 years. In addition, aspheric IOLs had statistical reductions in total spherical aberration at all follow-up examinations (P<.01). This study confirms that implantation of a modified aspheric IOL improves functional visual performance at 2 years postoperative.

  3. Observational Facts of Sustained Departure Plateau Vortexes

    Institute of Scientific and Technical Information of China (English)

    YU Shuhua; GAO Wenliang; PENG Jun; XIAO Yuhua

    2014-01-01

    By using the twice-daily atmospheric observation data from 1998 to 2012, station rainfall data, Tropical Rainfall Measure Mission (TRMM) data, as well as the plateau vortex and shear line year book, charac-teristics of the sustained departure plateau vortexes (SDPVs) are analyzed. Some new useful observational facts and understanding are obtained about the SDPV activities. The following results are obtained. (1) The active period of SDPVs is from June to August, most in July, unlike that of the unsustained depar-ture plateau vortexes (UDPVs), which have same occurrence frequencies in the three summer months. (2) The SDPVs, generated mainly in the Qumalai neighborhood and situated in a sheared surrounding, move eastward or northeastward, while the UDPVs are mainly led by the upper-level trough, and move eastward or southeastward. (3) The SDPVs influence wide areas of China, even far to the Korean Peninsula, Japan, and Vietnam. (4) The SDPVs change their intensities and properties on the way to the east. Most of them become stronger and produce downpour or sustained regional rainstorms to the south of Yellow River. (5) The longer the SDPV sustains, the more baroclinity it has. (6) When an SDPV moves into the sea, its central pressure descends and rainfall increases in all probability. (7) An SDPV might spin over the bend of the Yellow River when there exists a tropical cyclone in the East China Sea. It could also move oppositely to a landed tropical low pressure originated from the sea to the east of Taiwan or from the South China Sea.

  4. The effect of perceived mobility necessity in the choice of departure time

    DEFF Research Database (Denmark)

    Thorhauge, Mikkel; Cherchi, Elisabetta; Rich, Jeppe

    2014-01-01

    time. In this paper we investigate how the latent effect of the perceived mobility necessities affects the choice of departure time. A stated choice experiment collected among workers who commute to Copenhagen center is used to estimate 9 hybrid choice models where the discrete choice of departing...... before or later than the current trip depends on the latent construct of the perceived mobility necessities. Results show that individuals who perceive they have high mobility necessity tend to prefer the current departure time, and in particular dislike departing later. However the latent variables...

  5. The asymptotic variance of departures in critically loaded queues

    NARCIS (Netherlands)

    A. Al Hanbali; M.R.H. Mandjes (Michel); Y. Nazarathy (Yoni); W. Whitt

    2010-01-01

    htmlabstractWe consider the asymptotic variance of the departure counting process D(t) of the GI/G/1 queue; D(t) denotes the number of departures up to time t. We focus on the case that the system load rho equals 1, and prove that the asymptotic variance rate satisfies lim_t Var D(t)/t = lambda

  6. Influence of aspheric intraocular lens on frequency doubling technology and contrast sensitivity: a fellow eye study

    Directory of Open Access Journals (Sweden)

    Rodrigo França de Espíndola

    2014-12-01

    Full Text Available Purpose: To evaluate whether implantation of an aspheric intraocular lens (IOL results in reduced ocular aberrations and improved contrast sensitivity after cataract surgery and, therefore, changes on frequency-doubling technology (FDT testing. Methods: The present prospective clinical study enrolled 25 patients with bilateral cataract (50 eyes, who randomly received either an aspheric (Akreos AO or a spherical (Akreos Fit IOL in one eye and the other IOL in the second eye. Assessment 12 months postoperatively included photopic and mesopic contrast sensitivity testing. Higher-order aberrations (HOAs were computed. FDT testing was divided into four areas to evaluate the variation of the values at different points. The median values of the local pattern thresholds (median area contrast sensitivity [MACS] obtained with that division were calculated. Results: The Akreos AO group obtained statistically significantly lower values of HOAs and spherical aberration compared with the Akreos Fit group. There was a statistically significant between-group difference in contrast sensitivity under mesopic conditions at all spatial frequencies. No statistically significant differences were observed in mean deviation and pattern standard deviation. The aspheric IOL exhibited higher MACS in all areas, although a statistically significant difference was reached only in the 20-degree field area (P=0.043. Conclusion: Aspheric IOLs significantly reduced spherical aberration and HOAs, improving mesopic contrast sensitivity. Although there was a trend toward slightly improved FDT in the aspheric IOL group, it was not statistically significant.

  7. Multi-Dimensional Simulations of Radiative Transfer in Aspherical Core-Collapse Supernovae

    CERN Document Server

    Tanaka, Masaomi; Mazzali, Paolo A; Nomoto, Ken'ichi

    2008-01-01

    We study optical radiation of aspherical supernovae (SNe) and present an approach to verify the asphericity of SNe with optical observations of extragalactic SNe. For this purpose, we have developed a multi-dimensional Monte-Carlo radiative transfer code, SAMURAI (SupernovA MUlti-dimensional RAdIative transfer code). The code can compute the optical light curve and spectra both at early phases (<~ 40 days after the explosion) and late phases (~ 1 year after the explosion), based on hydrodynamic and nucleosynthetic models. We show that all the optical observations of SN 1998bw (associated with GRB 980425) are consistent with polar-viewed radiation of the aspherical explosion model with kinetic energy 20 x 10^{51} ergs. Properties of off-axis hypernovae are also discussed briefly.

  8. Use of piloted simulation for studies of fighter departure/spin susceptibility

    Science.gov (United States)

    Gilbert, W. P.; Nguyen, L. T.

    1978-01-01

    The NASA-Langley Research Center has incorporated into its stall/spin research program on military airplanes the use of piloted, fixed-base simulation to complement the existing matrix of unique research testing techniques. The piloted simulations of fighter stall/departure flight dynamics are conducted on the Langley Differential Maneuvering Simulator (DMS). The objectives of the simulation research are reviewed. The rationale underlying the simulation methods and procedures used in the evaluation of airplane characteristics is presented. The evaluation steps used to assess fighter stall/departure characteristics are discussed. Simulation results are presented to illustrate the flight dynamics phenomena dealt with. The considerable experience accumulated in the conduct of piloted stall/departure simulation indicates that simulation provides a realistic evaluation of an airplane's maneuverability at high angles of attack and an assessment of the departure and spin susceptibility of the airplane. This realism is obtained by providing the pilot a complete simulation of the airplane and control system which can be flown using a realistic cockpit and visual display in simulations of demanding air combat maneuvering tasks. The use of the piloted simulation methods and procedures described were found very effective in identifying stability and control problem areas and in developing automatic control concepts to alleviate many of these problems. A good level of correlation between simulated flight dynamics and flight test results were obtained over the many fighter configurations studied in the simulator.

  9. Grinding and polishing technology by computer controlled active lap for Φ1250mmF/1.5 aspheric mirror

    Science.gov (United States)

    Fan, Bin; Zeng, Zhige; Li, Xiaojin; Chen, Qiang; Gao, Pingqi; Zhou, Jiabin; Wan, Yongjian

    2010-05-01

    For large aspheric optical elements, Computer Controlled Active Lap(CCAL) manufacturing which developed in IOE (Institute of Optics and Electronics, Chinese Academy of Science), have some advantages such as higher manufacturing efficiency, lower middle-frequency and high-frequency errors comparing the fixed lapping technology and CCOS(Computer Controlled Optical Surface) technology. A paraboloid surface of Φ1250mmF/1.5 was grinded by the active lap bonded with ceramic pills, as well as polished will pitch bonded active lap. During polishing processing a null lens was designed to test the paraboloid surface, the final testing data of RMS with ZYGO interferometer reached to 0.027λ(λ=0.6328μm).

  10. A unified model for the spectrophotometric development of classical and recurrent novae: the role of asphericity of the ejecta

    CERN Document Server

    Shore, Steven N

    2013-01-01

    There is increasing evidence that the geometry, and not only the filling factors, of nova ejecta is important in the interpretation of their spectral and photometric developments. Ensembles of spectra and light curves have provided general typographies. This Letter suggests how these can be unified.The observed spread in the maximum magnitude - rate of decline (MMRD) relation is argued to result from the range of opening angles and inclination of the ejecta, and not only to their masses and velocities. The spectroscopic classes can be similarly explained and linked to the behavior of the light curves. The secondary maximum observed in some dust forming novae is a natural consequence of the asphericity. Neither secondary ejections nor winds are needed to explain the phenomenology. The spectrophotometric development of classical novae can be understood within a single phenomenological model with bipolar, although not jet-like, mass ejecta. High resolution spectropolarimetry will be an essential analytical tool.

  11. Control by Exception for Tactical Departure Scheduling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Tactical Departure Scheduling (TDS) is a common activity in Air Traffic Control (ATC) in the National Airspace System (NAS) that requires significant coordination...

  12. The asymptotic variance of departures in critically loaded queues

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Mandjes, M.R.H.; Nazarathy, Y.; Whitt, W.

    2011-01-01

    We consider the asymptotic variance of the departure counting process D(t) of the GI/G/1 queue; D(t) denotes the number of departures up to time t. We focus on the case where the system load ϱ equals 1, and prove that the asymptotic variance rate satisfies limt→∞varD(t) / t = λ(1 - 2 / π)(ca2 +

  13. Study on optical fabrication and metrology of precise convex aspheric mirror

    Science.gov (United States)

    Wang, Huijun; Xu, Jin; Wang, Peng; Li, Ang; Guo, Wen; Du, Yan

    2016-10-01

    Optical fabrication and metrology technologies are studied in the paper to improve the accuracy of surface figure of a convex aspheric mirror. First, the main specifications of a convex aspheric mirror which is chosen to be the secondary mirror of an optical system are presented. The aperture of the mirror is 400mm. The mirror is made of ultra-low expansion (ULE) glass with honeycomb sandwich structure to get the ideal lightweight requirement. Then the mirror is surfaced by ultrasonic grinding, smart robot lapping and smart robot polishing processes relatively. Large-apertured tool is applied to reduce the mid-frequency surface error. Both the contour measuring method in the grinding and lapping stage and the measuring method with meniscus lens and its calibration mirror in the polishing stage are studied. The final surface figure of the mirror is that the root mean-square value (RMS value) is 0.016λ (λ=632.8nm), which meets the requirement of the optical system. The results show that the forging surfacing processes and measuring methods are accurate and efficient to fabricate the convex aspheric mirror and can be applied in optical fabrication for larger-apertured convex aspheric mirrors.

  14. Comparison of Optical Performance in Eyes Implanted With Aspheric Foldable, Spherical Foldable, and Rigid PMMA IOLs

    NARCIS (Netherlands)

    van Gaalen, Kim W.; Jansonius, Nomdo M.; Koopmans, Steven A.; Kooijman, Aart C.

    2011-01-01

    PURPOSE: To compare the optical performance of rigid spherical polymethylmethacrylate (PMMA), foldable spherical, and foldable aspheric intraocular lenses (IOLs). METHODS: Measurements were obtained monocularly from pseudophakic patients with a PMMA IOL (Ophtec PC265y or Rayner 105U), spherical Acry

  15. Error analysis of a rotating mode diamond turning large aspherical mirrors

    Science.gov (United States)

    Han, Cheng-Shun; Zhang, Long-Jiang; Dong, Shen; Tan, Jiu-Bin

    2009-05-01

    A precision rotating mode diamond turnimg method used for machining large optical asphercial elements is introduced. The position errors between spindles of workpiece and cutting tool system are discussed, and error models of correctly forming the aspherical reference sphere are set up. The constructed models are used in adjusting the machine for ensuring the machining accuracy and efficiency.

  16. Precision Departure Release Capability (PDRC) Integration, Evaluation and Transition

    Science.gov (United States)

    Engelland, Shawn A.; Capps, Richard A.

    2011-01-01

    NASA's Precision Departure Release Capability (PDRC) research activity is assessing the use of surface trajectory-based takeoff (OFF) time estimates for en route domain departure scheduling in Call For Release situations. Current aircraft departure release times computed by an Air Traffic Management decision support tool to meet Call For Release constraints are based on coarse estimates of aircraft OFF times. Uncertainty in OFF time estimates may result in missed opportunities to merge into an overhead stream and lost throughput. However, technology exists to improve OFF time estimates by using more accurate aircraft trajectory predictions available in NextGen airport surface management decision support tools. PDRC findings are expected to be broadly applicable to NextGen integrated arrival/departure/surface implementations. For concept development and evaluation purposes this research activity integrates NASA's Surface Management System (SMS) OFF time prediction capabilities with Traffic Management Advisor (TMA) departure scheduling functions. PDRC field evaluations are being conducted at the North Texas (NTX) Research Station. The NASA/FAA Integrated Arrival/Departure/Surface Research Transition Team is using PDRC as a pathfinder for developing technology transfer mechanisms and procedures.

  17. Asphericity of pretherapeutic tumour FDG uptake provides independent prognostic value in head-and-neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Apostolova, Ivayla; Steffen, Ingo G. [Charite University Medical Center, Department of Nuclear Medicine, Berlin (Germany); Otto-von-Guericke University Clinic Magdeburg, Department of Radiology and Nuclear Medicine, Magdeburg (Germany); Wedel, Florian; Buchert, Ralph; Brenner, Winfried [Charite University Medical Center, Department of Nuclear Medicine, Berlin (Germany); Lougovski, Alexandr; Hofheinz, Frank [Helmholtz Center Dresden Rossendorf, Institute of Radiopharmaceutical Cancer Research, Dresden (Germany); Marnitz, Simone [Charite University Medical Center, Department of Radiooncology, Berlin (Germany); Derlin, Thorsten [University Medical Center Hamburg-Eppendorf, Department of Radiology, Hamburg (Germany); Amthauer, Holger [Otto-von-Guericke University Clinic Magdeburg, Department of Radiology and Nuclear Medicine, Magdeburg (Germany)

    2014-09-15

    To propose a novel measure, namely the 'asphericity' (ASP), of spatial irregularity of FDG uptake in the primary tumour as a prognostic marker in head-and-neck cancer. PET/CT was performed in 52 patients (first presentation, n = 36; recurrence, n = 16). The primary tumour was segmented based on thresholding at the volume-reproducible intensity threshold after subtraction of the local background. ASP was used to characterise the deviation of the tumour's shape from sphere symmetry. Tumour stage, tumour localisation, lymph node metastases, distant metastases, SUV{sub max}, SUV{sub mean}, metabolic tumour volume (MTV) and total lesion glycolysis (TLG) were also considered. The association of overall (OAS) and progression-free survival (PFS) with these parameters was analysed. Cox regression revealed high SUV{sub max} [hazard ratio (HR) = 4.4/7.4], MTV (HR = 4.6/5.7), TLG (HR = 4.8/8.9) and ASP (HR = 7.8/7.4) as significant predictors with respect to PFS/OAS in case of first tumour manifestation. The combination of high MTV and ASP showed very high HRs of 22.7 for PFS and 13.2 for OAS. In case of recurrence, MTV (HR = 3.7) and the combination of MTV/ASP (HR = 4.2) were significant predictors of PFS. ASP of pretherapeutic FDG uptake in the primary tumour improves the prediction of tumour progression in head-and-neck cancer at first tumour presentation. (orig.)

  18. Change in efficiency of aspheric intraocular lenses based on pupil diameter.

    Science.gov (United States)

    Eom, Youngsub; Yoo, Eunjoo; Kang, Su-Yeon; Kim, Hyo-Myung; Song, Jong-Suk

    2013-03-01

    To measure the effect of spherical aberration correction by aspheric intraocular lenses (IOLs) based on pupil diameter, and to determine the minimum pupil diameter for each aspheric IOL. Retrospective cross-sectional study. Eight-six patients (169 eyes) who were implanted with a HOYA AF-1 NY-60 (HOYA Corporation) or Tecnis ZCB00 1-piece IOL (Abbott Medical Optics Inc) were enrolled. Ocular, corneal, and internal spherical aberrations were measured at the 1-month postoperative visit using the Wavefront Analyzer KR-1W (Topcon). Minimum pupil diameter, which is required for each aspheric IOL to be effective, was calculated using a regression equation. The mean value of internal spherical aberration of the Tecnis ZCB00 group (-0.09 ± 0.094 μm) was lower than that of the HOYA NY-60 group (-0.05 ± 0.072 μm) (P = .005). The original negative spherical aberrations of the HOYA NY-60 (-0.18 μm) were measured at a pupil diameter of 5.6 mm, and for the Tecnis ZCB00 (-0.27 μm) at a pupil diameter of 6.1 mm. The aspheric IOL efficiency dropped to 0% when the pupil diameter was 3.47 mm for the Tecnis ZCB00 group and 3.71 mm for the HOYA NY-60 group. When the pupil diameters of patients are smaller than 3.4 mm for the Tecnis ZCB00 and 3.7 mm for the HOYA NY-60, the spherical aberration correction using these aspheric IOLs seems to be ineffective. Approximately 10% of the eyes showed smaller pupil size than the minimum effective diameter under mesopic conditions. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Precision Departure Release Capability (PDRC): NASA to FAA Research Transition

    Science.gov (United States)

    Engelland, Shawn; Davis, Thomas J.

    2013-01-01

    After takeoff, aircraft must merge into en route (Center) airspace traffic flows which may be subject to constraints that create localized demand-capacity imbalances. When demand exceeds capacity, Traffic Management Coordinators (TMCs) and Frontline Managers (FLMs) often use tactical departure scheduling to manage the flow of departures into the constrained Center traffic flow. Tactical departure scheduling usually involves use of a Call for Release (CFR) procedure wherein the Tower must call the Center to coordinate a release time prior to allowing the flight to depart. In present-day operations release times are computed by the Center Traffic Management Advisor (TMA) decision support tool based upon manual estimates of aircraft ready time verbally communicated from the Tower to the Center. The TMA-computed release time is verbally communicated from the Center back to the Tower where it is relayed to the Local controller as a release window that is typically three minutes wide. The Local controller will manage the departure to meet the coordinated release time window. Manual ready time prediction and verbal release time coordination are labor intensive and prone to inaccuracy. Also, use of release time windows adds uncertainty to the tactical departure process. Analysis of more than one million flights from January 2011 indicates that a significant number of tactically scheduled aircraft missed their en route slot due to ready time prediction uncertainty. Uncertainty in ready time estimates may result in missed opportunities to merge into constrained en route flows and lead to lost throughput. Next Generation Air Transportation System plans call for development of Tower automation systems capable of computing surface trajectory-based ready time estimates. NASA has developed the Precision Departure Release Capability (PDRC) concept that improves tactical departure scheduling by automatically communicating surface trajectory-based ready time predictions and

  20. Large-scale circulation departures related to wet episodes in northeast Brazil

    Science.gov (United States)

    Sikdar, D. N.; Elsner, J. B.

    1985-01-01

    Large scale circulation features are presented as related to wet spells over northeast Brazil (Nordeste) during the rainy season (March and April) of 1979. The rainy season season is devided into dry and wet periods, the FGGE and geostationary satellite data was averaged and mean and departure fields of basic variables and cloudiness were studied. Analysis of seasonal mean circulation features show: lowest sea level easterlies beneath upper level westerlies; weak meridional winds; high relative humidity over the Amazon basin and relatively dry conditions over the South Atlantic Ocean. A fluctuation was found in the large scale circulation features on time scales of a few weeks or so over Nordeste and the South Atlantic sector. Even the subtropical High SLP's have large departures during wet episodes, implying a short period oscillation in the Southern Hemisphere Hadley circulation.

  1. Large-scale circulation departures related to wet episodes in north-east Brazil

    Science.gov (United States)

    Sikdar, Dhirendra N.; Elsner, James B.

    1987-01-01

    Large scale circulation features are presented as related to wet spells over northeast Brazil (Nordeste) during the rainy season (March and April) of 1979. The rainy season is divided into dry and wet periods; the FGGE and geostationary satellite data was averaged; and mean and departure fields of basic variables and cloudiness were studied. Analysis of seasonal mean circulation features show: lowest sea level easterlies beneath upper level westerlies; weak meridional winds; high relative humidity over the Amazon basin and relatively dry conditions over the South Atlantic Ocean. A fluctuation was found in the large scale circulation features on time scales of a few weeks or so over Nordeste and the South Atlantic sector. Even the subtropical High SLPs have large departures during wet episodes, implying a short period oscillation in the Southern Hemisphere Hadley circulation.

  2. Development of a New Departure Aversion Standard for Light Aircraft

    Science.gov (United States)

    Borer, Nicholas K.

    2017-01-01

    The Federal Aviation Administration (FAA) and European Aviation Safety Agency (EASA) have recently established new light aircraft certification rules that introduce significant changes to the current regulations. The changes include moving from prescriptive design requirements to performance-based standards, transferring many of the acceptable means of compliance out of the rules and into consensus standards. In addition, the FAA/EASA rules change the performance requirements associated with some of the more salient safety issues regarding light aircraft. One significant change is the elimination of spin recovery demonstration. The new rules now call for enhanced stall warning and aircraft handling characteristics that demonstrate resistance to inadvertent departure from controlled flight. The means of compliance with these changes in a safe, cost-effective manner is a challenging problem. This paper discusses existing approaches to reducing the likelihood of departure from controlled flight and introduces a new approach, dubbed Departure Aversion, which allows applicants to tailor the amount of departure resistance, stall warning, and enhanced safety equipment to meet the new proposed rules. The Departure Aversion approach gives applicants the freedom to select the most cost-effective portfolio for their design, while meeting the safety intent of the new rules, by ensuring that any combination of the selected approaches will be at a higher equivalent level of safety than today's status quo.

  3. Fluctuations in airport arrival and departure traffic: A network analysis

    Institute of Scientific and Technical Information of China (English)

    Li Shan-Mei; Xu Xiao-Hao; Meng Ling-Hang

    2012-01-01

    Air traffic is a typical complex system,in which movements of traffic components (pilots,controllers,equipment,and environment),especially airport arrival and departure traffic,form complicated spatial and temporal dynamics.The fluctuations of airport arrival and departure traffic are studied from the point of view of networks as the special correlation between different airports.Our collected flow volume data on the time-dependent activity of US airport arrival and departure traffic indicate that the coupling between the average flux and the fluctuation of an individual airport obeys a certain scaling law with a wide variety of scaling exponents between 1/2 and 1.These scaling phenomena can explain the interaction between the airport internal dynamics (e.g.queuing at airports,a ground delay program and following flying traffic) and a change in the external (network-wide) traffic demand (e.g.an increase in traffic during peak hours every day),allowing us to further understand the mechanisms governing the collective behaviour of the transportation system.We separate internal dynamics from external fluctuations using a scaling law which is helpful for us to systematically determine the origin of fluctuations in airport arrival and departure traffic,uncovering the collective dynamics.Hot spot features are observed in airport traffic data as the dynamical inhomogeneity in the fluxes of individual airports.The intrinsic characteristics of airport arrival and departure traffic under severe weather is discussed as well.

  4. Contrast visual acuity after multifocal intraocular lens implantation:aspheric versus spherical design

    Directory of Open Access Journals (Sweden)

    Jun-Hua Li

    2014-02-01

    Full Text Available AIM: To evaluate contrast visual acuity (CVA after implantation of an aspheric apodized diffractive intraocular lens (IOL or a spherical apodized diffractive IOL in cataract surgery.METHOD: This prospective randomized controlled study with a 12-month follow-up compared the results of cataract surgery with implantation of an aspheric AcrySof ReSTOR SN6AD3 IOL (30 eyes and a spherical AcrySof ReSTOR SN60D3 IOL (30 eyes. CVA with best distance correction was measured at 4 contrast levels (100%, 25%, 10% and 5% under 3 levels of chart luminance [250, 85 and 25 candelas per square meter (cd/m2] using a multi-functional visual acuity tester (MFVA-100.RESULTS:At 12 months after surgery, there were no statistically significant differences in 100% CVA and 25% CVA under 250cd/m2 (P100%=0.875 and P25%=0.057 and 85cd/m2 (P100%=0.198 and P25%=0.193 between the aspheric group and the spherical group. However, the 10% CVA and 5% CVA were significant better in aspheric group than spherical group under 250cd/m2 (P10%=0.042 and P5%=0.007 and 85cd/m2 (P10%=0.002 and P5%=0.039. Under the luminance level of 25cd/m2, no significant differences was found in the 100% CVA between the 2 group (P100%=0.245, while aspheric group had better visual acuity in the remaining 3 contracts (P25%=0.023, P10%=0.026 and P5%=0.002, respectively.CONCULSION:The aspheric AcrySof ReSTOR SN6AD3 IOL provided patients with better low-contrast visual acuity than the spherical AcrySof ReSTOR SN60D3 IOL.Keyword:cataract surgery; intraocular lens; contrast sensitivity; visual acuity

  5. Numerical solution of optimal departure frequency of Taipei TMS

    Science.gov (United States)

    Young, Lih-jier; Chiu, Chin-Hsin

    2016-05-01

    Route Number 5 (Bannan Line) of Taipei Mass Rapid Transit (MRT) is the most popular line in the Taipei Metro System especially during rush hours periods. It has been estimated there are more than 8,000 passengers on the ticket platform during 18:00∼19:00 at Taipei main station. The purpose of this research is to predict a specific departure frequency of passengers per train. Monte Carlo Simulation will be used to optimize departure frequency according to the passenger information provided by 22 stations, i.e., 22 random variables of route number 5. It is worth mentioning that we used 30,000 iterations to get the different samples of the optimization departure frequency, i.e., 10 trains/hr which matches the practical situation.

  6. A Multiclass, Multimodal Dynamic Traffic Assignment Model with Departure Time

    Directory of Open Access Journals (Sweden)

    Meng Meng

    2014-01-01

    Full Text Available The paper develops a multiclass, multimodal dynamic traffic equilibrium model with consideration of the departure time choice problem. Travelers choose the departure time and the route simultaneously with a Logit-based structure. The route travel cost is a summation of travel time and schedule delay which is associated with arrival time at destination. In addition, the travelers are classified into three groups according to their value of time. A variational inequality (VI formulation is proposed based on the equilibrium conditions. Two examples are given to testify the effectiveness of the model and the solution algorithm. The model can give the optimal travel route as well as the best departure time, which would contribute to traffic control and dynamic route guidance.

  7. Departure Traj ectory Design Based on Pareto Ant Colony Algorithm

    Institute of Scientific and Technical Information of China (English)

    SunFanrong; HanSongchen; QianGe

    2016-01-01

    Due to the ever-increasing air traffic flow,the influence of aircraft noise around the airport has become significant.As most airlines are trying to decrease operation cost,stringent requirements for more simple and effi-cient departure traj ectory are on a rise.Therefore,a departure traj ectory design was established for performance-based navigation technology,and a multi-obj ective optimization model was developed,with constraints of safety and noise influence,as well as optimization targets of efficiency and simplicity.An improved ant colony algorithm was then proposed to solve the optimization problem.Finally,an experiment was conducted using the Lanzhou ter-minal airspace operation data,and the results showed that the designed departure traj ectory was feasible and effi-cient in decreasing the aircraft noise influence.

  8. An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT

    Directory of Open Access Journals (Sweden)

    Riccardo Pozza

    2016-11-01

    Full Text Available In this article, an Arrival and Departure Time Predictor (ADTP for scheduling communication in opportunistic Internet of Things (IoT is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process.

  9. An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT.

    Science.gov (United States)

    Pozza, Riccardo; Georgoulas, Stylianos; Moessner, Klaus; Nati, Michele; Gluhak, Alexander; Krco, Srdjan

    2016-11-04

    In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process.

  10. Comprehensive Optimization of Emergency Evacuation Route and Departure Time under Traffic Control

    Directory of Open Access Journals (Sweden)

    Guo Li

    2014-01-01

    Full Text Available With the frequent occurrence of major emergencies, emergency management gets high attention from all around the world. This paper investigates the comprehensive optimization of major emergency evacuation route and departure time, in which case the evacuation propagation mechanism is considered under traffic control. Given the practical assumptions, we first establish a comprehensive optimization model based on the simulation of evacuation route and departure time. Furthermore, we explore the reasonable description method of evacuation traffic flow propagation under traffic control, including the establishment of traffic flow propagation model and the design of the simulation mudule that can simulate the evacuation traffic flow. Finally, we propose a heuristic algorithm for the optimization of this comprehensive model. In case analysis, we take some areas in Beijing as the evaluation sources to verify the reliability of our model. A series of constructive suggestions for Beijing's emergency evacuation are proposed, which can be applied to the actual situation under traffic control.

  11. The Effects of the Uncertainty of Departures on Multi-Center Traffic Management Advisor (TMA) Scheduling

    Science.gov (United States)

    Thipphavong, Jane; Landry, Steven J.

    2005-01-01

    The Multi-center Traffic Management Advisor (McTMA) provides a platform for regional or national traffic flow management, by allowing long-range cooperative time-based metering to constrained resources, such as airports or air traffic control center boundaries. Part of the demand for resources is made up of proposed departures, whose actual departure time is difficult to predict. For this reason, McTMA does not schedule the departures in advance, but rather relies on traffic managers to input their requested departure time. Because this happens only a short while before the aircraft's actual departure, McTMA is unable to accurately predict the amount of delay airborne aircraft will need to take in order to accommodate the departures. The proportion of demand which is made up by such proposed departures increases as the horizon over which metering occurs gets larger. This study provides an initial analysis of the severity of this problem in a 400-500 nautical mile metering horizon and discusses potential solutions to accommodate these departures. The challenge is to smoothly incorporate departures with the airborne stream while not excessively delaying the departures.' In particular, three solutions are reviewed: (1) scheduling the departures at their proposed departure time; (2) not scheduling the departures in advance; and (3) scheduling the departures at some time in the future based on an estimated error in their proposed time. The first solution is to have McTMA to automatically schedule the departures at their proposed departure times. Since the proposed departure times are indicated in their flight times in advance, this method is the simplest, but studies have shown that these proposed times are often incorrect2 The second option is the current practice, which avoids these inaccuracies by only scheduling aircraft when a confirmed prediction of departure time is obtained from the tower of the departure airport. Lastly, McTMA can schedule the departures at a

  12. Precision Departure Release Capability (PDRC) Concept of Operations

    Science.gov (United States)

    Engelland, Shawn; Capps, Richard A.; Day, Kevin Brian

    2013-01-01

    After takeoff, aircraft must merge into en route (Center) airspace traffic flows which may be subject to constraints that create localized demandcapacity imbalances. When demand exceeds capacity Traffic Management Coordinators (TMCs) often use tactical departure scheduling to manage the flow of departures into the constrained Center traffic flow. Tactical departure scheduling usually involves use of a Call for Release (CFR) procedure wherein the Tower must call the Center TMC to coordinate a release time prior to allowing the flight to depart. In present-day operations release times are computed by the Center Traffic Management Advisor (TMA) decision support tool based upon manual estimates of aircraft ready time verbally communicated from the Tower to the Center. The TMA-computed release is verbally communicated from the Center back to the Tower where it is relayed to the Local controller as a release window that is typically three minutes wide. The Local controller will manage the departure to meet the coordinated release time window. Manual ready time prediction and verbal release time coordination are labor intensive and prone to inaccuracy. Also, use of release time windows adds uncertainty to the tactical departure process. Analysis of more than one million flights from January 2011 indicates that a significant number of tactically scheduled aircraft missed their en route slot due to ready time prediction uncertainty. Uncertainty in ready time estimates may result in missed opportunities to merge into constrained en route flows and lead to lost throughput. Next Generation Air Transportation System (NextGen) plans call for development of Tower automation systems capable of computing surface trajectory-based ready time estimates. NASA has developed the Precision Departure Release Capability (PDRC) concept that uses this technology to improve tactical departure scheduling by automatically communicating surface trajectory-based ready time predictions to the

  13. Conformal interpolating algorithm based on B-spline for aspheric ultra-precision machining

    Science.gov (United States)

    Li, Chenggui; Sun, Dan; Wang, Min

    2006-02-01

    Numeric control machining and on-line compensation for aspheric surface are key techniques for ultra-precision machining. In this paper, conformal cubic B-spline interpolating curve is first applied to fit the character curve of aspheric surface. Its algorithm and process are also proposed and imitated by Matlab7.0 software. To evaluate the performance of the conformal B-spline interpolation, comparison was made between linear and circular interpolations. The result verifies this method can ensure smoothness of interpolating spline curve and preserve original shape characters. The surface quality interpolated by B-spline is higher than by line and by circle arc. The algorithm is benefit to increasing the surface form precision of workpiece during ultra-precision machining.

  14. Non-Radial Instabilities and Progenitor Asphericities in Core-Collapse Supernovae

    CERN Document Server

    Mueller, B

    2014-01-01

    Since core-collapse supernova simulations still struggle to produce robust neutrino-driven explosions in 3D, it has been proposed that asphericities caused by convection in the progenitor might facilitate shock revival by boosting the activity of non-radial hydrodynamic instabilities in the post-shock region. We investigate this scenario in depth using 42 relativistic 2D simulations with multi-group neutrino transport to examine the effects of velocity and density perturbations in the progenitor for different perturbation geometries that obey fundamental physical constraints (like the anelastic condition). As a framework for analysing our results, we introduce semi-empirical scaling laws relating neutrino heating, average turbulent velocities in the gain region, and the shock deformation in the saturation limit of non-radial instabilities. The squared turbulent Mach number, , reflects the violence of aspherical motions in the gain layer, and explosive runaway occurs for ~0.3, corresponding to a reduction of t...

  15. SOFTWARE-CONTROLLED SYSTEM OF ULTRA-PRECISION MACHINING AXISYMMETRIC ASPHERIC MIRROR

    Institute of Scientific and Technical Information of China (English)

    GUO Yinbiao; WEI Lizhen

    2006-01-01

    In order to improve machining accuracy and efficiency, a software-controlled system of ultra-precision machining for axisymmetric aspheric mirror, using techniques of error compensation,remote transmission and modularization, is designed based on industrial PC, Windows 2000 work platform and Visual Basic 6.0. By experiments, this system realizes functions of ultra-precision machining, machining error compensation, remote data transmission and automatic data transformation among first machining, compensation machining and accuracy measurement. The actual application shows that error compensation improves machining accuracy, remote transmission improves machining efficiency while modularization avoids repeated work and improves design efficiency. Therefore, the system has met ultra-precision machining need for aspheric mirror.

  16. Effection of grinding system rigidity ultra-precision grinding of aspheric mould and error compensation

    Science.gov (United States)

    Yin, S. H.; Gong, S.

    2016-10-01

    In ultra-precision oblique axis grinding process for machining micro aspherical mould, form error of aspherical surface is caused by the inconsistence elastic deformation of grinding system, which derived from differences velocity from inside to out. In this case, whole PV value can meet requirements, however, pits are produced in central after error compensation, which is unworkable. In this paper, mechanism of machining error caused by grinding system rigidity is analyzed, and experiments are carried out. Form error compensation grinding are carried out in the central local area, based on traditional error compensation method, which can effectively eliminate the pits of surface center. In this method, cemented carbide YG8 which diameter is about 6mm is ground. The results showed that the form accuracy under PV 200 nm and under PV 50 nm within the scope of 1 mm, and the surface roughness under Ra2nm.

  17. Use of Virtual Medium in Designing of the CGH Wave Front Generator for Aspheric Testing

    Institute of Scientific and Technical Information of China (English)

    KANG Guo-guo; XIE Jing-hui; LIU Yi

    2007-01-01

    Design method and procedures of computer-generated hologram (CGH) used for aspheric test are introduced in detail.For CGH phase calculation,virtual medium which has zero refractive index at given wavelength is used to model ideal aspheric wavefront.Reflective Fresnel zones located in a ring area concentric to the CGH structure is designed to reduce or eliminate alignment errors.Substrate figure error,pattern distortion,etching and duty cycle variations that influence the reconstructed wavefront are quantitatively analyzed in theory and corresponding error equations are obtained to guide the tolerance distribution during CGH fabricating.A design example is given and the uncertainty of measurement achieves λ/20.

  18. A Spectral Representation for Spin-Weighted Spheroidal Wave Operators with Complex Aspherical Parameter

    CERN Document Server

    Finster, Felix

    2015-01-01

    A family of spectral decompositions of the spin-weighted spheroidal wave operator is constructed for complex aspherical parameters with bounded imaginary part. As the operator is not symmetric, its spectrum is complex and Jordan chains may appear. We prove uniform upper bounds for the length of the Jordan chains and the norms of the idempotent operators mapping onto the invariant subspaces. The completeness of the spectral decomposition is proven.

  19. Contrast sensitivity after refractive lens exchange with a multifocal diffractive aspheric intraocular lens

    Directory of Open Access Journals (Sweden)

    Teresa Ferrer-Blasco

    2013-04-01

    Full Text Available PURPOSE: To evaluate distance and near contrast sensitivity (CS under photopic and mesopic conditions before and after refractive lens exchange (RLE and implantation of the aspheric AcrySof®ReSTOR® (SN6AD3 model intraocular lens (IOL. METHODS:Seventy-four eyes of 37 patients after RLE underwent bilateral implantation with the aspheric AcrySof ReSTOR IOL. The patient sample was divided into myopic and hyperopic groups. Monocular uncorrected visual acuity at distance and near (UCVA and UCNVA, respectively and monocular best corrected visual acuity at distance and near (BCVA and BCNVA, respectively were measured before and 6 months postoperatively. Monocular CS function was measured at three different luminance levels (85, 5 and 2.5 cd/m² before and after RLE. Post-implantation results at 6 months were compared with those found before surgery. RESULTS: Our results revealed that patients in both groups obtained good UCVA and BCVA after RLE at distance and near vision in relation to pre-surgery values. No statistically significant differences were found between the values of CS pre and post-RLE at distance and near, at any lighting condition and spatial frequency (p>0.002. CONCLUSIONS: Refractive lens exchange with aspheric AcrySof ReSTOR IOL in myopic and hyperopic population provided good visual function and yield good distance and near CS under photopic and mesopic conditions.

  20. Higher order aberration comparison between two aspherical intraocular lenses: MC6125AS and Akreos advanced optics

    Institute of Scientific and Technical Information of China (English)

    Mohammad; Taher; Rajabi; Sara; Korouji; Mahgol; Farjadnia; Mohammad; Naderan; Mohammad; Bagher; Rajabi; Bahram; Khosravi; Seyed; Mehdi; Tabatabaie

    2015-01-01

    AIM: To compare higher order aberrations in two aspherical intraocular lenses(IOLs): Akreos advanced optics(AO) and Dr. Schmidt Microcrystalline 6125 aspheric anterior surface(MC6125AS) with each other. METHODS: Forty eyes of 39 patients underwent phacoemulsification and Akreos AO and MC6125 AS were implanted in their eyes in a random manner. Three months post-operatively, higher order aberrations including spherical aberration, coma aberration, and total aberrations were measured and compared.RESULTS: The total aberration was 0.24±0.17 in eyes with Dr. Schmidt and 0.20 ±0.01 in eyes with Akreos AO(P =0.361). The mean of coma aberration was 0.17 ±0.21 and 0.09 ±0.86 in Dr. Schmidt and Akreos lenses,respectively(P =0.825). Total spherical aberration was almost the same in both groups(mean: 0.05, P =0.933).Best corrected visual acuity in Akreos AO(0.10±0.68) and Dr. Schmidt(0.09±0.67) did not differ significantly(P =0.700). CONCLUSION: There is no statistically significant difference in the higher order aberrations between these two aspherical lenses.

  1. Optimization Model of Organization Modes Choice of Sunset-departure and Sunrise-arrival Train Based on Simultaneous Integrated Maintain Time on High-speed Railway%基于全线矩形天窗的高速铁路夕发朝至列车开行模式选择优化模型

    Institute of Scientific and Technical Information of China (English)

    张天伟; 聂磊; 贺振欢

    2015-01-01

    Three organization modes ,i.e. ,waiting for simultaneous integrated maintain time(SIMT) on a high speed railway(HSR) station(WHRS) ,transfer from HSR to conventional railway(CR) before SIMT and arri‐ving at the destination(T HCD) on the CR , transfer from HSR to CR before SIM T and from CR to HSR after SIMT(HCCH),were proposed according to SIMT on HSR .The operation process of sunset‐departure and sunrise‐arrival trains in every organization mode was analyzed . The nonlinear integer program optimization model of operation mode choice was built , with passenger satisfaction on departure and arrival moments and fare attraction w hich affect passengers'choice behavior , section carrying capacity and difficulty of transportation organization adjustment which affect the quality and quantity of rail transport products supply as objective func‐tion . Variable logical , the moment of train operation process , the relation betw een the selection of cities and the arrival or departure moment at the cities ,and the number of arrival‐departrue railway lines were considered in its constraints .An appropriate size numerical example shows that when SIMT from 00 :00 to 04 :00 ,WHRS and 300 km/h of multiple units are preferred for the long distance train OD . T HCD and 250 km/h of multiple units are the first choice for the medium distance train OD .%在全线矩形天窗下提出等线、下线、下线‐上线共3种高速铁路夕发朝至列车开行模式,分析每种模式下列车运行过程。以影响旅客选择行为的列车始发、终到时刻满意度、票价吸引力、影响铁路运输产品供给数量及质量的区段通过能力和运输组织难度为目标函数,构建满足变量逻辑约束、列车运行过程约束、关键地点与运行时刻约束、到发线数量约束的开行模式选择非线性整数规划优化模型,通过算例应用验证了构建模型的可行性和有效性。研究结果表明:在0:00~04:00开

  2. Tick off to Take off: The Pre-Departure Guide

    Science.gov (United States)

    Arthur, Erica

    2009-01-01

    "Tick Off to Take Off (TOTTO)" is an online pre-departure guide for UK undergraduates intending to study abroad. It aims to simplify the application process, centralise information, increase efficiency and improve retention rates. TOTTO responds to the changing climate surrounding study abroad in UK universities and offers one way to…

  3. Exact Methods for Solving the Train Departure Matching Problem

    DEFF Research Database (Denmark)

    Haahr, Jørgen Thorlund; Bull, Simon Henry

    In this paper we consider the train departure matching problem which is an important subproblem of the Rolling Stock Unit Management on Railway Sites problem introduced in the ROADEF/EURO Challenge 2014. The subproblem entails matching arriving train units to scheduled departing trains at a railway...

  4. Easing the Transition: Teaching Migrants in the Orderly Departure Program.

    Science.gov (United States)

    Webster, Marian; Belmont, Susan

    1986-01-01

    Immigrants leaving Vietnam through the Orderly Departure Program in Bangkok, Thailand, experience stress and difficulties very different from those endured by refugees fleeing by land or boat. The cultural orientation program addresses their needs to assimilate their loss, gain equilibrium, and get resettlement guidance and information. These…

  5. Clinical Application of Aspheric Intraocular Lens%浅谈非球面人工晶状体的临床应用

    Institute of Scientific and Technical Information of China (English)

    许玉梅

    2016-01-01

    目的:通过非球面人工晶状体植入术后视功能的变化,观察治疗效果,提出治疗建议,客观评价非球面人工晶状体的临床作用。方法从眼球面像差的特性,非球面人工晶状体的设计及矫正目标,非球面人工晶状体临床应用注意事项,非球面人工晶状体的视觉质量评价等方面进行分析。结果虽然非球面人工晶状体眼术后的高阶像差低于球面人工晶状体,但其视力和对比敏感度的结果并不完全与之相对应。由于目前我们对人眼波前像差的认识还不够深入,检测仪器不够完善,各阶像差与视功能之间的关系尚需进一步的研究。结论正常瞳孔下非球面人工晶状体眼与球面人工晶状体眼相比,非球面人工晶体可以有效减少球面像差,提高部分空间频率的对比敏感度,使患者拥有更好地视觉质量,但其不能体现减少术眼后高阶像差的优势。%Objective Through the changes of visual function after implantation of aspheric intraocular lens(IOL)observed treatment effect,treatment recommendations,and objective evaluation of non spherical intraocular lens(IOL)clinical effect. MethodsFrom the ocular wavefront aberration characteristics,the design of aspheric intraocular lens and correctional goal and clinical application of aspheric intraocular lenses note,aspheric intraocular lens visual quality evaluation were analyzed.Results Although the high order aberrations of the patients with non spherical intraocular lens were lower than that of the spherical intraocular lens,the visual acuity and contrast sensitivity were not completely corresponding with the results. Because at present we of wavefront aberration of understanding is not deep enough,detection equipment is not perfect,aberration and depending on the relationship between function stil need to further study.Conclusion With normal pupil non compared to spherical intraocular lens eyes and spherical

  6. Recent advances in the model of aspherical dust dynamics for GIADA experiment in the coma of 67P/Churyumov-Gerasimenko

    Science.gov (United States)

    Ivanovski, Stavro; Zakharov, Vladimir; Crifo, Jean-Francois; Della Corte, Vincenzo; Fulle, Marco; Rotundi, Alessandra

    2013-04-01

    Introduction. We report the latest improvements of the model of aspherical dust grain dynamics [1] in the cometary atmosphere of 67P/Churyumov- Gerasimenko(67P/C-G). The model is aimed to support the scien- tific objectives of GIADA (Grain Impact Analyzer and Dust Accumulator) in-situ experiment [2] on board of the ESA ROSETTA spacecraft. The instrument will measure individual dust grain mass, number density and velocity in the immediate vicinity of the cometary nucleus. In this report we discuss the distinctions in the dy- namics of the aspherical dust in comparison with the spherical approximation developed in the currently used 3D+t spherical dust models [3,4]. Model. We assume that dust grains are homogeneous, isothermal polygonal convex bodies (close to ellipsoid of revolution with different aspect ratios of axes). The grains are moving under influence of three forces: aero- dynamic , gravitational and torque. The gas distribution (density, velocity, temperature) in the coma is taken from the Euler solution for spherical expansion. The aerodynamic force we estimate from expressions for free molecular interaction. On the comet surface we postulate the distribution function of ejection velocity and the distribution function of initial orientation of the grains. From the same origin on the surface we trace a number of grain trajectories with different initial conditions. Then we derive an average trajectory with mean parameters and the dispersion around it. We evaluate the goodness of spherical grain approximation through the deviation of the spherical grain trajectory from the averaged trajectory. Results. We have studied various distribution functions of initial orientation of aspherical rotating grains. The results of our simulations show that the dynamics of aspherical grains is very sensitive to the initial parameters (orientation and ejection velocity). Therefore, we see that the velocity along the trajectory of the identical aspherical grains could change

  7. 基于粘刚塑性模型非球面透镜三维模压成型模拟%Simulation of 3D molding of aspheric optical glass lens based on viscous-rigid model

    Institute of Scientific and Technical Information of China (English)

    张小兵

    2015-01-01

    The temperature dependence of flow stress model and glass material parameters at high temperature was analyzed and discussed. The three⁃dimensional finite element model of compression molding of aspheric lens at high temperature was established using viscous⁃rigid model based on DEFORM 3D. The whole process of optical glass spherical L⁃BAL42 preform being molded into aspheric lens was studied by numerical simulation. It is found that maximum stress is at lens edge and stresses increase rapidly when mold is closed,leading to the lens edge most easily being broken,the result is validated by experiments. Residual stress will increase with increasing compression rate and the cooling rate,and the rules of aspheric lens deviation were analyzed. Finally aspheric surface deviation was compensated during the mold design stage. It is found that the aspheric surface deviation will decrease,deviation changes from positive to negative.%分析与探讨了高温玻璃的应力流动模型及其材料参数的温度相关性。利用粘刚塑性力学模型,基于三维有限元软件DEFORM 3D建立非球面透镜高温模压有限元模型,对光学玻璃L-BAL42球形预制件模压成非球面透镜的整个过程进行了数值仿真,发现非球面透镜应力分布规律:透镜边缘处应力最大,在和模阶段应力快速增加,导致透镜边缘处最易破碎,结果得到实验的验证。采用较大的模压速度及冷却速度将导致残余应力增加,同时分析了透镜非球面偏差变化规律。最后在模具设计时将非球面偏差补偿进去,发现非球面透镜偏差减少,由正偏差变为负偏差。

  8. A sharp upper bound for departure from normality

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.L.

    1993-08-01

    The departure from normality of a matrix is a real scalar that is impractical to compute if a matrix is large and its eigenvalues are unknown. A simple formula is presented for computing an upper bound for departure from normality in the Frobenius norm. This new upper bound is cheaper to compute than the upper bound derived by Henrici. Moreover, the new bound is sharp for Hermitian matrices, skew-Hermitian matrices and, in general, any matrix with eigenvalues that are horizontally or vertically aligned in the complex plane. In terms of applications, the new bound can be used in computing bounds for the spectral norm of matrix functions or bounds for the sensitivity of eigenvalues to matrix perturbations.

  9. Departure time choice: Modelling individual preferences, intention and constraints

    DEFF Research Database (Denmark)

    Thorhauge, Mikkel

    working hours) as the penalty of late arrival is very likely to be higher for individuals with constraints on arrival time. However, flexibility is not only a matter of fixed arrival time. Activities can be mandatory or discretionary (Yamamoto and Kitamura, 1999), performed alone or jointly with family......D thesis is as follows. Firstly, it provides evidence of a fully efficient stated choice design for a departure time context. Using a pivot design (Rose et al., 2008) built around a reference trip (usually from the day before), the thesis shows that the efficient design performs well in cases where good...... whether they are constrained. The thesis also provides empirical evidences of the policy implication of not accounting for other activities and their constraints. Thirdly, the thesis shows that the departure time choice can be partly explained by psychological factors, which have previously been neglected...

  10. The Ideal Mixing Departure in Vector Meson Physics

    CERN Document Server

    Epele, L N; Grunfeld, A G

    2002-01-01

    In this work we study the departure for the ideal $\\phi-\\omega$ mixing angle in the frame of the Nambu-Jona-Lasinio model. We have shown that in that context, the flavour symmetry breaking is unable to produce the shifting in the mixing angle. We introduce a nonet symmetry breaking in the neutral vector sector to regulate the non-strange content of the $\\phi$ meson. The phenomenon is well reproduced by our proposal.

  11. Prospective randomized study of clinical performance of 3 aspheric and 2 spherical intraocular lenses in 250 eyes.

    Science.gov (United States)

    Caporossi, Aldo; Martone, Gianluca; Casprini, Fabrizio; Rapisarda, Lorenzo

    2007-09-01

    To compare the quality of vision with aspheric and spherical intraocular lenses (IOLs) in pseudophakic patients. This prospective, comparative, randomized study included 250 eyes of 125 patients with bilateral cataracts. Patients were randomly assigned to receive either IOLs with a spherical biconvex optic (Acrysof SN6OAT [Alcon] or Sensar AR40e [Advanced Medical Optics, AMO]) or IOLs with an aspheric optic (Acrysof IQ SN6OWF [Alcon], Tecnis Z9000 [AMO], or Sofport L161AO [Bausch & Lomb]). Ophthalmologic examination including best spectacle-corrected visual acuity, pupil size, ocular dominance investigation, contrast sensitivity under mesopic and photopic conditions, and wavefront analysis was performed 2 months postoperatively. Aspheric IOLs showed better contrast sensitivity compared to spherical IOLs at spatial frequencies of 6, 12, and 18 cycles per degree (cpd) under photopic conditions and at all spatial frequencies under mesopic conditions. There was no significant difference among the three aspheric IOLs at all spatial frequencies under either photopic or mesopic conditions. Mean total spherical aberration was statistically lower in dominant eyes with aspheric IOLs (0.05 +/- 0.06, 0.11 +/- 0.1, and 0.19 +/- 0.08 pm for the Tecnis Z9000, Acrysof IQ SN6OWF, and Sofport L161AO, respectively) compared with eyes with spherical IOLs (0.62 +/- 0.24 and 0.46 +/- 0.19 microm for the Acrysof SN6OAT and Sensar AR40e, respectively) for a 5-mm pupil diameter. The aspheric IOLs had less wavefront aberrations and performed better under both photopic and mesopic contrast sensitivity compared to the spherical IOLs. These findings confirm it is possible to improve the optical performance of IOLs by modifying the surfaces.

  12. Optical Metrology of Aspheric and Freeform Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Science Missions Directorate seeks technology for cost-effective high-performance advanced space telescopes for astrophysics and Earth science applications....

  13. On-axis reverse Hartmann test in aspheric optical surface test with the optical flat calibration

    Science.gov (United States)

    Xia, Zhengzheng; Hui, Mei; Zhao, Zhu; Liu, Ming; Dong, Liquan; Liu, Xiaohua; Kong, Lingqin; Zhao, Yuejin

    2016-09-01

    The Reverse Hartmann test is developed rapidly, robustly, and accurately in measuring precision aspheric surface. The onaxis design provides better control of the astigmatism in the test. We use an on-axis Hartmann test in reverse to measure the aspheric optical mirrors. In the configuration, the LCD with a light pattern on the screen illuminates to the tested surface, and a 2μm-thick pellicle beam splitter is employed to obtain the coaxial light model. An optical flat with 1/20λ surface precision is used to calibrate the rays which pass through the external pinhole and image at the detector, and the data are processed to obtain the direction vectors of arbitrary reflected rays. The surface gradients are determined by the spatial equations of incident and reflected rays which have been calibrated. The shape of surface is finally reconstructed by Zernike polynomial fitting. The experiments include measuring a 76.2mm off-axis parabolic mirror and a 76.2mm spherical mirror. The experimental results show coaxial reverse Hartmann test system may allow for accurate measurements with uncertainties in the micrometer range using cost-effective equipments.

  14. A fast processing route of aspheric polydimethylsiloxane lenses array (APLA) and optical characterization for smartphone microscopy

    Science.gov (United States)

    Fuh, Yiin-Kuen; Lai, Zheng-Hong

    2017-02-01

    A fast processing route of aspheric polydimethylsiloxane (PDMS) lenses array (APLA) is proposed via the combined effect of inverted gravitational and heat-assisted forces. The fabrication time can be dramatically reduced to 30 s, compared favorably to the traditional duration of 2 hours of repeated cycles of addition-curing processes. In this paper, a low-cost flexible lens can be fabricated by repeatedly depositing, inverting, curing a hanging transparent PDMS elastomer droplet on a previously deposited curved structure. Complex structures with aspheric curve features and various focal lengths can be successfully produced and the fabricated 4 types of APLA have various focal lengths in the range of 7.03 mm, 6.00 mm, 5.33 mm, and 4.43 mm, respectively. Empirically, a direct relationship between the PDMS volume and focal lengths of the lenses can be experimentally deducted. Using these fabricated APLA, an ordinary commercial smartphone camera can be easily transformed to a low-cost, portable digital microscopy (50×magnification) such that point of care diagnostic can be implemented pervasively.

  15. Designing null phase screens to test a fast plano-convex aspheric lens

    Science.gov (United States)

    DelOlmo-Márquez, Jesús; Castán-Ricaño, Diana; Avendaño-Alejo, Maximino; Díaz-Uribe, Rufino

    2015-08-01

    We have obtained a formula to represent the wavefront produced by a plano-convex aspheric lens with symmetry of revolution considering a plane wavefront propagating parallel to the optical axis and impinging on the refracting surface, it is called a zero-distance phase front, being it the first wavefront to be out of the optical system. Using a concept of differential geometry called parallel curves it is possible to obtain an analytic formula to represent the wavefront propagated at arbitrary distances through the optical axis. In order to evaluate qualitatively a plano-convex aspheric lens, we have modified slightly an interferometer Tywman-Green as follow: In the reference beam we use a plane mirror and the beam of test we have used a spatial light modulator (SLM) to compensate the phase produced by the lens under test. It will be called a null phase interferometer. The main idea is to recombine both wavefronts in order to get a null interferogram, otherwise we will associate the patterns of the interferogram to deformations of the lens under test. The null phase screens are formed with concentric circumferences assuming different gray levels printed on SLM.

  16. A Paradigm Lost New Theories for Aspherical PNe

    CERN Document Server

    Frank, A I

    1999-01-01

    Theoretical Models for the shaping of PNe are reviewed in light of new high resolution images. The new data indicate the purely hydrodynamic interacting stellar winds model can not recover the full variety of shapes and kinematics. New models, some speculative, others more firmly grounded are discussed. In particular, accretion disks and magnetic fields are identified as two of the most promising avenues of future research. Outstanding issues such as jet formation by PNe disks and dynamo activity in P-AGB stars remain to studied. Finally, new simulations of the Egg Nebula are presented as an example of a ``paleontological'' study designed to recover the history of an individual object.

  17. Multi-Dimensional Simulations for Early Phase Spectra of Aspherical Hypernovae: SN 1998bw and Off-Axis Hypernovae

    CERN Document Server

    Tanaka, Masaomi; Mazzali, Paolo A; Nomoto, Ken'ichi

    2007-01-01

    Early phase optical spectra of aspherical jet-like supernovae (SNe) are presented. We focus on energetic core-collapse SNe, or hypernovae. Based on hydrodynamic and nucleosynthetic models, radiative transfer in SN atmosphere is solved with a multi-dimensional Monte-Carlo radiative transfer code, SAMURAI. Since the luminosity is boosted in the jet direction, the temperature there is higher than in the equatorial plane by ~ 2,000 K. This causes anisotropic ionization in the ejecta. Emergent spectra are different depending on viewing angle, reflecting both aspherical abundance distribution and anisotropic ionization. Spectra computed with an aspherical explosion model with kinetic energy 20 x 10^{51} ergs are compatible with those of the Type Ic SN 1998bw if ~ 10-20% of the synthesized metals are mixed out to higher velocities. The simulations enable us to predict the properties of off-axis hypernovae. Even if an aspherical hypernova explosion is observed from the side, it should show hypernova-like spectra but ...

  18. Feasibility assessment of visual quality analyzer KR-1W guiding personalized aspheric IOL implantation

    Directory of Open Access Journals (Sweden)

    Xiao-Li Wang

    2015-01-01

    Full Text Available AIM: To discuss the feasibility of using the visual quality analyzer KR-1W to guide the relatively personalized aspheric intraocular lens(IOLimplants to make the whole eye spherical aberration close to 0.1μm.METHODS: In this prospective case series study, the corneal spherical aberration with 6mm aperture of 73 patients(100 eyeswas measured with KR-1W Visual Function Analyzer 1d before surgery. For the sake of the whole postoperative spherical aberration were close to 0.1μm, 9 cases(16 eyeswith corneal spherical aberration 0.35μm were implanted Tecnis ZA9003 IOL, named Tecnis group. Aspherical IOL was implanted after phacoemulsification through a cornea 2.75mm incision without suture.Uncorrected visual acuity, beat corrected visual acuity, spherical aberration of the whole eye and jnternal optics(mainly IOLat 6mm pupil diameter were examined at 3mo postoperatively. The relevant data were analyzed using t-test and variance analysis.RESULTS: The whole ocular spherical aberration at 6mm pupil diameter in all postoperative were 0.084±0.032μm; in Tecnis group, the data were 0.091 ± 0.021μm; in AO group, the data were 0.0814-0.013μm; IQ group were 0.093±0.042μm. There was no significantly different between the predicted value and actual value of ocular spherical aberration at 6 mm pupil diameter in all postoperative(t=1.932, P=0.061and in the three groups. The difference value in the predicted values of the preoperative spherical aberrations of the whole eye and the actual values after surgery was 0.013±0.041μm; there was no statistically significant difference(F=2.537, P=0.091. Respectively compared the uncorrected visual acuity and besta corrected visual acuity among three groups of postoperative, no significant difference were found(F=0.897, P=0.421; F=1.423, P=0.097.CONCLUSION: Personality selection of aspheric IOL based on preoperative corneal spherical aberration of patients is feasible and produces satisfactory target postoperative

  19. Optimizing distance image quality of an aspheric multifocal intraocular lens using a comprehensive statistical design approach.

    Science.gov (United States)

    Hong, Xin; Zhang, Xiaoxiao

    2008-12-01

    The AcrySof ReSTOR intraocular lens (IOL) is a multifocal lens with state-of-the-art apodized diffractive technology, and is indicated for visual correction of aphakia secondary to removal of cataractous lenses in adult patients with/without presbyopia, who desire near, intermediate, and distance vision with increased spectacle independence. The multifocal design results in some optical contrast reduction, which may be improved by reducing spherical aberration. A novel patent-pending approach was undertaken to investigate the optical performance of aspheric lens designs. Simulated eyes using human normal distributions were corrected with different lens designs in a Monte Carlo simulation that allowed for variability in multiple surgical parameters (e.g. positioning error, biometric variation). Monte Carlo optimized results indicated that a lens spherical aberration of -0.10 microm provided optimal distance image quality.

  20. Wide-Spectrum Microscope with a Long Working Distance Aspherical Objective Based on Obscuration Constraint

    Directory of Open Access Journals (Sweden)

    Weibo Wang

    2016-11-01

    Full Text Available We present an approach for an initial configuration design based on obscuration constraint and on-axis Taylor series expansion to realize the design of long working distance microscope (numerical aperture (NA = 0.13 and working distance (WD = 525 mm with a low obscuration aspherical Schwarzschild objective in wide-spectrum imaging (λ = 400–900 nm. Experiments of the testing on the resolution target and inspection on United States Air Force (USAF resolution chart and a line charge-coupled device (CCD (pixel size of 14 μm × 56 μm with different wavelength light sources (λ = 480 nm, 550 nm, 660 nm, 850 nm were implemented to verify the validity of the proposed method.

  1. Characteristic analysis of aspheric quasi-optical lens antenna in millimeter-wave radiometer imaging system.

    Science.gov (United States)

    Kim, Won-Gyum; Moon, Nam-Won; Singh, Manoj Kumar; Kim, Hwang-Kyeom; Kim, Yong-Hoon

    2013-02-20

    Quasi-optical imaging systems require low blurring effect and large depth of focus (DOF) to get an acceptable sharpness of the image. To reduce aberration-limited blurring, the aspheric convex plano lenses with an aperture diameter of 350 mm are designed in W-band. We analyzed theoretically and experimentally the millimeter-wave band lens characteristics, such as beam spot size, spatial resolution (SR), and DOF, via f-number. It is first used to verify the DOF through f-number in the system-level test with the developed W-band radiometer imaging system. We have confirmed that the larger f-number of quasi-optical lens leads to a larger DOF but a lower SR.

  2. Differences between real and predicted corneal shapes after aspherical corneal ablation

    Science.gov (United States)

    Anera, Rosario G.; Villa, César; Jiménez, José R.; Gutiérrez, Ramón; Jiménez del Barco, Luis

    2005-07-01

    We study the differences between real and expected corneal shapes, using an aspherical ablation algorithm with a known equation and avoiding the limitation imposed by most studies of refractive surgery in which the ablation equations are not known. We have calculated the theoretical corneal shape predicted by this algorithm, comparing this shape with the real corneal topography. The results indicate that the deviations that appear in the corneal shape are significant for visual performance and for the correction of eye aberrations. If we include in this analysis the effect of reflection losses and nonnormal incidence on the cornea, we can reduce corneal differences, but they will remain significant. These results confirm that it is essential to minimize corneal differences to achieve effective correction in refractive surgery.

  3. Optical Design with Aspherical Gratings - the Example of the Uv-Prim Spectrograph

    Science.gov (United States)

    Lemaitre, G.

    1981-11-01

    Aspherical diffraction gratings have been produced by the elastic relaxation method. These gratings lead to more nearly ideal mountings from the standpoints of a small number of surfaces, of a wide field and of a fast aperture ratio. The UV-PRIM spectrograph is the first instrument of this type to have been constructed. Resumé en français. Des réseaux asphériques ont été obtenus en utilisant la méthode des relaxations élastiques. Ces réseaux de diffraction conduisent à un montage très performant du point de vue du faible nombre de surfaces optiques, d'un grand champ et d'un rapport d'ouverture élevé. Le spectrographe UV-PRIM est le premier instrument de ce type à avoir été construit.

  4. Stray, swing and scatter: angular momentum evolution of orbits and streams in aspherical potentials

    CERN Document Server

    Erkal, Denis; Belokurov, Vasily

    2016-01-01

    In aspherical potentials orbital planes continuously evolve. The gravitational torques impel the angular momentum vector to precess, that is to slowly stray around the symmetry axis, and nutate, i.e. swing up and down periodically in the perpendicular direction. This familiar orbital pole motion - if detected and measured - can reveal the shape of the underlying gravitational potential, the quantity only crudely gauged in the Galaxy so far. Here we demonstrate that the debris poles of stellar tidal streams show a very similar straying and swinging behavior, and give analytic expressions to link the amplitude and the frequency of the pole evolution to the flattening of the dark matter distribution. Most importantly, we explain how the differential orbital plane precession leads to the broadening of the stream and show that streams on polar orbits ought to scatter faster. We provide expressions for the stream width evolution as a function of the axisymmetric potential flattening and the angle from the symmetry ...

  5. Aspherical rotating dust dynamics for GIADA experiment in the coma of 67P/Churyumov- Gerasimenko

    Science.gov (United States)

    Ivanovski, S.; Zakharov, V.; Della Corte, V.; Lucarelli, F.; Crifo, J.-F.; Rotundi, A.; Fulle, M.

    2014-04-01

    The recent advances of the 3D+t cometary aspherical dust model [1, 2] have been used for studying the dust dynamics in the circumnuclear coma of the comet 67P/Churyumov-Gerasimenko (67P/C-G). This model will be used for analysis of the forthcoming in-situ dust data collected by GIADA (Grain Impact Analyzer and Dust Accumulator) [3] on board of the ESA ROSETTA probe. In the present research we study dust grain motion driven by the aerodynamic and gravitational forces and discuss the influence of dust grain's shape. We show the differences in dust grain velocities owing to the grain shape, initial orientation and rotation. The outcomes of the model are used to forecast by means of GIPSI [4] the dust distribution seen by GIADA at some of the ROSETTA operational phases.

  6. Reminder concerning vaccinations prior to departure on duty travel

    CERN Multimedia

    2006-01-01

    For many years the Medical Service has administered vaccination to any member of the personnel going on duty travel to countries with an endemic risk of disease. An appointment must be made with the medical secretariat (73186) a minimum of one month before departure. The doctors will write you a prescription for the vaccines and medicines at the time of the appointment. The vaccines and medicines will be reimbursed by your health insurance and the remaining balance by the relevant CERN Department. During the appointment you will be provided with documentation on the risks and the preventive measures to be taken. This service is offered to you but is not compulsory and you remain entirely free to choose your doctor. Please do not forget to bring your vaccination card to the appointment.

  7. New Physical Optics Method for Curvilinear Refractive Surfaces and its Verification in the Design and Testing of W-band Dual-Aspheric Lenses

    Science.gov (United States)

    2013-10-01

    aspheric ( plano -convex) and (b) optimized dual- aspheric W-band PTFE lenses as needed for a non-paraxial system of Fig. 1 . . 10 3 Profiles of (a) full...is comparable with the given lens diameter Dc = 140mm. Following conventional solutions, non-paraxial lenses of plano -convex type are usually em...optimized by applying more advanced methods, e.g., full-wave approaches, etc. When considering plano -convex lenses by ray-tracing methods, we arrive at

  8. Low-frequency Carbon Radio Recombination Lines. I. Calculations of Departure Coefficients

    Science.gov (United States)

    Salgado, F.; Morabito, L. K.; Oonk, J. B. R.; Salas, P.; Toribio, M. C.; Röttgering, H. J. A.; Tielens, A. G. G. M.

    2017-03-01

    In the first paper of this series, we study the level population problem of recombining carbon ions. We focus our study on high quantum numbers, anticipating observations of carbon radio recombination lines to be carried out by the Low Frequency Array. We solve the level population equation including angular momentum levels with updated collision rates up to high principal quantum numbers. We derive departure coefficients by solving the level population equation in the hydrogenic approximation and including low-temperature dielectronic capture effects. Our results in the hydrogenic approximation agree well with those of previous works. When comparing our results including dielectronic capture, we find differences that we ascribe to updates in the atomic physics (e.g., collision rates) and to the approximate solution method of the statistical equilibrium equations adopted in previous studies. A comparison with observations is discussed in an accompanying article, as radiative transfer effects need to be considered.

  9. Low Frequency Carbon Radio Recombination Lines I: Calculations of Departure Coefficients

    CERN Document Server

    Salgado, F; Oonk, J B R; Salas, P; Toribio, M C; Rottgering, H J A; Tielens, A G G M

    2016-01-01

    In the first paper of this series, we study the level population problem of recombining carbon ions. We focus our study on high quantum numbers anticipating observations of Carbon Radio Recombination Lines to be carried out by the LOw Frequency ARray (LOFAR). We solve the level population equation including angular momentum levels with updated collision rates up to high principal quantum numbers. We derive departure coefficients by solving the level population equation in the hydrogenic approximation and including low temperature dielectronic recombination effects. Our results in the hydrogenic approximation agree well with those of previous works. When comparing our results including dielectronic recombination we find differences which we ascribe to updates in the atomic physics (e.g., collision rates) and to the approximate solution method of the statistical equilibrium equations adopted in previous studies. A comparison with observations is discussed in an accompanying article, as radiative transfer effect...

  10. A more general Force Balance Model to predict Bubble Departure and Lift-off Diameters in flow boiling

    Science.gov (United States)

    Kommajosyula, Ravikishore; Mazzocco, Thomas; Ambrosini, Walter; Baglietto, Emilio

    2016-11-01

    Accurate prediction of Bubble Departure and Lift-off Diameters is key for development of closures in two-phase Eulerian CFD simulation of Flow Boiling, owing to its sensitivity in the Heat Flux partitioning approach. Several models ranging from simple correlations to solving complex force balance models have been proposed in literature; however, they rely on data-fitting for specific databases, and have shown to be inapplicable for general flow applications. The aim of this study is to extend the approach by proposing a more consistent and general formulation that accounts for relevant forces acting on the Bubble at the point of Departure and Lift-off. Among the key features of the model, the Bubble Inclination angle is treated as an unknown to be inferred along with the Departure Diameter, and the relative velocity of the bubble sliding on the surface, is modeled to determine the Lift-off Diameter. A novel expression is developed for the bubble growth force in terms of flow quantities, based on extensive data analysis. The model has been validated using 6 different experimental databases with varying flow conditions and 3 fluids. Results show high accuracy of predictions over a broad range, outperforming existing models both in terms of accuracy and generality. CASL - The Consortium for Advanced Simulation of LWRs.

  11. Very High Load Capacity Air Bearing Spindle for Large Diamond Turning Machines Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Diamond turning is able to produce highly aspheric visible quality optics which can be easily aligned. Very large optical systems such as OWL and EUSO are impossible...

  12. 19 CFR 4.64 - Electronic passenger and crew member departure manifests.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Electronic passenger and crew member departure manifests. 4.64 Section 4.64 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND... Customs and Border Protection (CBP) an electronic passenger departure manifest and an electronic...

  13. 33 CFR 165.113 - Security Zone: Dignitary arrival/departure Logan International Airport, Boston, MA

    Science.gov (United States)

    2010-07-01

    .../departure Logan International Airport, Boston, MA 165.113 Section 165.113 Navigation and Navigable Waters... Guard District § 165.113 Security Zone: Dignitary arrival/departure Logan International Airport, Boston... governments arriving at, or departing from, Logan International Airport and as determined by the transit...

  14. ON THE TRANSIENT DEPARTURE PROCESS OF Mx/G/1 QUEUEING SYSTEM WITH SINGLE SERVER VACATION

    Institute of Scientific and Technical Information of China (English)

    Yinghui TANG

    2007-01-01

    This paper studies the transient departure process of Mx/G/1 queueing system with single server vacation. We present a simple probability decomposition method to derive the expected number of departures occurring in finite time interval from any initial state and the asymptotic expansion of the expected number. Especially, we derive some more practical results for some special cases.

  15. Input-Output Modeling and Control of the Departure Process of Congested Airports

    Science.gov (United States)

    Pujet, Nicolas; Delcaire, Bertrand; Feron, Eric

    2003-01-01

    A simple queueing model of busy airport departure operations is proposed. This model is calibrated and validated using available runway configuration and traffic data. The model is then used to evaluate preliminary control schemes aimed at alleviating departure traffic congestion on the airport surface. The potential impact of these control strategies on direct operating costs, environmental costs and overall delay is quantified and discussed.

  16. Left Unsaid: The Role of Work Expectations and Psychological Contracts in Faculty Careers and Departure

    Science.gov (United States)

    O'Meara, KerryAnn; Bennett, Jessica Chalk; Neihaus, Elizabeth

    2016-01-01

    Early career faculty bring many expectations to the door-steps of their new academic homes. Yet such expectations are often left unsaid. Unfortunately, what is left unsaid can be a major factor in faculty departure. This study makes a distinct contribution to the departure literature by examining the psychological contracts and work expectations…

  17. Bubble Departure Diameter and Bubble Release Frequency Measurement from TAMU Subcooled Flow Boiling Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jun Soo [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-12-01

    The bubble departure diameter and bubble release frequency were obtained through the analysis of TAMU subcooled flow boiling experimental data. The numerous images of bubbles at departure were analyzed for each experimental condition to achieve the reliable statistics of the measured bubble parameters. The results are provided in this report with simple discussion.

  18. Assessing ecological departure from reference conditions with the Fire Regime Condition Class (FRCC) Mapping Tool

    Science.gov (United States)

    Stephen W. Barrett; Thomas DeMeo; Jeffrey L. Jones; J.D. Zeiler; Lee C. Hutter

    2006-01-01

    Knowledge of ecological departure from a range of reference conditions provides a critical context for managing sustainable ecosystems. Fire Regime Condition Class (FRCC) is a qualitative measure characterizing possible departure from historical fire regimes. The FRCC Mapping Tool was developed as an ArcMap extension utilizing the protocol identified by the Interagency...

  19. Method to design two aspheric surfaces for a wide field of view imaging system with low distortion.

    Science.gov (United States)

    Bian, Yinxu; Li, Haifeng; Wang, Yifan; Zheng, Zhenrong; Liu, Xu

    2015-09-20

    This paper presents a distortion correction method for designing a wide field of view (FOV) lens for an imaging system. The lens is composed of two aspheric surfaces and several spheres. In the preliminary design, profiles of the aspheric surfaces can be obtained according to aplanatism, refraction law, and polynomial fitting methods, where the numeric computation, the differential geometry computation, and the polynomial fitting algorithm are stated in detail. Then the lens is optimized by the damped least squares method. Theoretically, this method cannot eliminate aberrations absolutely but can balance some kinds of aberrations to the image well. Furthermore, a projector lens with a wide FOV, low distortion, and low throw ratio [TR = (projection distance)/(image diagonal size)] is designed successfully by this method.

  20. Accurate testing of aspheric surfaces using the transport of intensity equation by properly selecting the defocusing distance.

    Science.gov (United States)

    Soltani, Peyman; Darudi, Ahmad; Nehmetallah, George; Moradi, Ali Reza; Amiri, Javad

    2016-12-10

    In the last decade, the transport of intensity has been increasingly used in microscopy, wavefront sensing, and metrology. In this study, we verify by simulation and experiment the use of the transport of intensity equation (TIE) in the accurate testing of optical aspheric surfaces. Guided by simulation results and assuming that the experimental setup parameters and the conic constants are known, one can estimate an appropriate defocusing distance Δz that leads to an accurate solution of the TIE. In this paper, this method is verified through the construction of a non-nulled experiment for testing the 2D profile of an aspheric surface. The theoretical method and experimental results are compared to validate the results. Finally, to validate the TIE methodology, the phase distribution obtained by TIE is compared with the phase distribution obtained by a Shack-Hartmann sensor.

  1. The Lunar IceCube Mission Design: Construction of Feasible Transfer Trajectories with a Constrained Departure

    Science.gov (United States)

    Folta, David C.; Bosanac, Natasha; Cox, Andrew; Howell, Kathleen C.

    2016-01-01

    Lunar IceCube, a 6U CubeSat, will prospect for water and other volatiles from a low-periapsis, highly inclined elliptical lunar orbit. Injected from Exploration Mission-1, a lunar gravity assisted multi-body transfer trajectory will capture into a lunar science orbit. The constrained departure asymptote and value of trans-lunar energy limit transfer trajectory types that re-encounter the Moon with the necessary energy and flight duration. Purdue University and Goddard Space Flight Center's Adaptive Trajectory Design tool and dynamical system research is applied to uncover cislunar spatial regions permitting viable transfer arcs. Numerically integrated transfer designs applying low-thrust and a design framework are described.

  2. Multidisciplinary Simulation of Graphite-Composite and Cermet Fuel Elements for NTP Point of Departure Designs

    Science.gov (United States)

    Stewart, Mark E.; Schnitzler, Bruce G.

    2015-01-01

    This paper compares the expected performance of two Nuclear Thermal Propulsion fuel types. High fidelity, fluid/thermal/structural + neutronic simulations help predict the performance of graphite-composite and cermet fuel types from point of departure engine designs from the Nuclear Thermal Propulsion project. Materials and nuclear reactivity issues are reviewed for each fuel type. Thermal/structural simulations predict thermal stresses in the fuel and thermal expansion mis-match stresses in the coatings. Fluid/thermal/structural/neutronic simulations provide predictions for full fuel elements. Although NTP engines will utilize many existing chemical engine components and technologies, nuclear fuel elements are a less developed engine component and introduce design uncertainty. Consequently, these fuel element simulations provide important insights into NTP engine performance.

  3. What is known about the effects of medical tourism in destination and departure countries? A scoping review

    Directory of Open Access Journals (Sweden)

    Snyder Jeremy

    2010-11-01

    Full Text Available Abstract Background Medical tourism involves patients intentionally leaving their home country to access non-emergency health care services abroad. Growth in the popularity of this practice has resulted in a significant amount of attention being given to it from researchers, policy-makers, and the media. Yet, there has been little effort to systematically synthesize what is known about the effects of this phenomenon. This article presents the findings of a scoping review examining what is known about the effects of medical tourism in destination and departure countries. Methods Drawing on academic articles, grey literature, and media sources extracted from18 databases, we follow a widely used scoping review protocol to synthesize what is known about the effects of medical tourism in destination and departure countries. The review design has three main stages: (1 identifying the question and relevant literature; (2 selecting the literature; and (3 charting, collating, and summarizing the data. Results The large majority of the 203 sources accepted into the review offer a perspective of medical tourism from the Global North, focusing on the flow of patients from high income nations to lower and middle income countries. This greatly shapes any discussion of the effects of medical tourism on destination and departure countries. Five interrelated themes that characterize existing discussion of the effects of this practice were extracted from the reviewed sources. These themes frame medical tourism as a: (1 user of public resources; (2 solution to health system problems; (3 revenue generating industry; (4 standard of care; and (5 source of inequity. It is observed that what is currently known about the effects of medical tourism is minimal, unreliable, geographically restricted and mostly based on speculation. Conclusions Given its positive and negative effects on the health care systems of departure and destination countries, medical tourism is a

  4. What is known about the effects of medical tourism in destination and departure countries? A scoping review

    Science.gov (United States)

    2010-01-01

    Background Medical tourism involves patients intentionally leaving their home country to access non-emergency health care services abroad. Growth in the popularity of this practice has resulted in a significant amount of attention being given to it from researchers, policy-makers, and the media. Yet, there has been little effort to systematically synthesize what is known about the effects of this phenomenon. This article presents the findings of a scoping review examining what is known about the effects of medical tourism in destination and departure countries. Methods Drawing on academic articles, grey literature, and media sources extracted from18 databases, we follow a widely used scoping review protocol to synthesize what is known about the effects of medical tourism in destination and departure countries. The review design has three main stages: (1) identifying the question and relevant literature; (2) selecting the literature; and (3) charting, collating, and summarizing the data. Results The large majority of the 203 sources accepted into the review offer a perspective of medical tourism from the Global North, focusing on the flow of patients from high income nations to lower and middle income countries. This greatly shapes any discussion of the effects of medical tourism on destination and departure countries. Five interrelated themes that characterize existing discussion of the effects of this practice were extracted from the reviewed sources. These themes frame medical tourism as a: (1) user of public resources; (2) solution to health system problems; (3) revenue generating industry; (4) standard of care; and (5) source of inequity. It is observed that what is currently known about the effects of medical tourism is minimal, unreliable, geographically restricted and mostly based on speculation. Conclusions Given its positive and negative effects on the health care systems of departure and destination countries, medical tourism is a highly significant and

  5. What is known about the effects of medical tourism in destination and departure countries? A scoping review.

    Science.gov (United States)

    Johnston, Rory; Crooks, Valorie A; Snyder, Jeremy; Kingsbury, Paul

    2010-11-03

    Medical tourism involves patients intentionally leaving their home country to access non-emergency health care services abroad. Growth in the popularity of this practice has resulted in a significant amount of attention being given to it from researchers, policy-makers, and the media. Yet, there has been little effort to systematically synthesize what is known about the effects of this phenomenon. This article presents the findings of a scoping review examining what is known about the effects of medical tourism in destination and departure countries. Drawing on academic articles, grey literature, and media sources extracted from18 databases, we follow a widely used scoping review protocol to synthesize what is known about the effects of medical tourism in destination and departure countries. The review design has three main stages: (1) identifying the question and relevant literature; (2) selecting the literature; and (3) charting, collating, and summarizing the data. The large majority of the 203 sources accepted into the review offer a perspective of medical tourism from the Global North, focusing on the flow of patients from high income nations to lower and middle income countries. This greatly shapes any discussion of the effects of medical tourism on destination and departure countries. Five interrelated themes that characterize existing discussion of the effects of this practice were extracted from the reviewed sources. These themes frame medical tourism as a: (1) user of public resources; (2) solution to health system problems; (3) revenue generating industry; (4) standard of care; and (5) source of inequity. It is observed that what is currently known about the effects of medical tourism is minimal, unreliable, geographically restricted and mostly based on speculation. Given its positive and negative effects on the health care systems of departure and destination countries, medical tourism is a highly significant and contested phenomenon. This is especially

  6. A new way to measure the departure from thermodynamic equilibrium in stellar atmospheres

    Institute of Scientific and Technical Information of China (English)

    Zhong-Quan Qu; Long-Fei Hao; Xiao-Li Yan; Cheng-Lin Xu

    2009-01-01

    A new way to measure the departure from thermodynamic equilibrium is proposed based on the departure factor which evaluates the deviation from a Boltzmann level distribution, used by Short and Hauschildt (2005) and others. The way is based on an explicit relationship describing the departure factor as a function of line to continuum source, dynamic temperature and line photon frequency, under three assumptions that the scattering can be neglected, the background continuum can be treated as a Planck function, and finally the complete redistribution can be true. It has the advantage that the departure can be very conveniently evaluated from the spectral analysis with only the radiative transfer involved. Some physical insights are recovered for some extreme cases.Some example calculations of the departure are presented for the quiet Sun, faint solar flare and strong solar flare for the generally used solar chromospheric lines: Hα, Hβ,CaII H, K and triplet. It is revealed that in the case of solar flares, the departure is less than thermodynamic equilibrium along the larger depth range than in the quiet sun due to chromospheric condensation. It becomes hard to distinguish the departures for the different lines of the same atom or ion. It is expected that this investigation can be constructive for studying stellar atmospheres in cases where the three assumptions are close to reality.

  7. Enhancement of spike coherence by the departure from Gaussian noise in a Hodgkin-Huxley neuron

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Experimental study has shown that non-Gaussian noise exists in sensory systems like neurons.The departure from Gaussian behavior is a characteristic parameter of non-Gaussian noise.In this paper,we have numerically studied the effect of a particular kind of non-Gaussian colored noise(NGN),especially its departure q from Gaussian noise(q = 1),on the spiking activity in a deterministic Hodgkin-Huxley(HH) neuron driven by sub-threshold periodic stimulus.Simulation results show that the departure q can affect the spiking activity induced by noise intensity D.For smaller q values,the minimum in the variation coefficient(CV) as a function of noise intensity(D) becomes smaller,showing that D-induced stochastic resonance(SR) becomes strengthened.Meanwhile,depending on the value of D,q can either enhance or reduce the spiking regularity.Interestingly,CV changes non-monotonously with varying q and passes through a minimum at an intermediate q,representing the presence of "departure-induced SR".This result shows that appropriate departures of the NGN can enhance the spike coherence in the HH neuron.Since the departure of the NGN determines the probability distribution and hence may denote the type of the noise,"departure-induced SR" shows that different types of noise can enhance the spike coherence,and hence may improve the timing precision of sub-threshold signal encoding in the HH neuron.

  8. Aspheric surface lens for LED collimating illumination with low Fresnel loss

    Science.gov (United States)

    Chen, Xindu; Lin, Jiaping; Liu, Zhanji; Wu, Peixuan; Wang, Han

    2016-12-01

    An aspheric surface lens is presented to realize collimating illumination with low Fresnel loss based on Fresnel equations and Snell's law. The smooth 2D contour of refractive optical surface is constructed from a set of cubic Bézier segments, whose control points are computed by deCasteljau algorithm. Simulation results show that the optical efficiency of 90.82% is achieved under a divergence angle of ±2.87° for an extended light-emitting diode (LED) source with chip size of 1 mm × 1 mm and the Fresnel loss is only 8.76%, whose optical efficiency has improved 14.3% than traditional collimating lens. By employing this proposed surface construction method, the largest divergence angle of collimating lens for point source is only 0.26° with 15 feature points on each refractive surface, while more than 2° for the traditional method. Therefore, the beams are well controlled with fewer feature data points. Tolerance analyses are also conducted in detail.

  9. Aspheric surface lens for LED collimating illumination with low Fresnel loss

    Science.gov (United States)

    Chen, Xindu; Lin, Jiaping; Liu, Zhanji; Wu, Peixuan; Wang, Han

    2017-02-01

    An aspheric surface lens is presented to realize collimating illumination with low Fresnel loss based on Fresnel equations and Snell's law. The smooth 2D contour of refractive optical surface is constructed from a set of cubic Bézier segments, whose control points are computed by deCasteljau algorithm. Simulation results show that the optical efficiency of 90.82% is achieved under a divergence angle of ±2.87° for an extended light-emitting diode (LED) source with chip size of 1 mm × 1 mm and the Fresnel loss is only 8.76%, whose optical efficiency has improved 14.3% than traditional collimating lens. By employing this proposed surface construction method, the largest divergence angle of collimating lens for point source is only 0.26° with 15 feature points on each refractive surface, while more than 2° for the traditional method. Therefore, the beams are well controlled with fewer feature data points. Tolerance analyses are also conducted in detail.

  10. Aspherical lens design using hybrid neural-genetic algorithm of contact lenses.

    Science.gov (United States)

    Yen, Chih-Ta; Ye, Jhe-Wen

    2015-10-01

    The design of complex contact lenses involves numerous uncertain variables. How to help an optical designer to first design the optimal contact lens to reduce discomfort when wearing a pair of glasses is an essential design concern. This study examined the impact of aberrations on contact lenses to optimize a contact lens design for myopic and astigmatic eyes. In general, two aspherical surfaces can be assembled in an optical system to reduce the overall volume size. However, this design reduces the spherical aberration (SA) values at wide contact radii. The proposed optimization algorithm with optical design can be corrected to improve the SA value and, thus, reduce coma aberration (TCO) values and enhance the modulation transfer function (MTF). This means integrating a modified genetic algorithm (GA) with a neural network (NN) to optimize multiple-quality characteristics, namely the SA, TCO, and MTF, of contact lenses. When the proposed optional weight NN-GA is implemented, the weight values of the fitness function can be varied to adjust system performance. The method simplifies the selection of parameters in the optimization of optical systems. Compared with the traditional CODE V built-in optimal scheme, the proposed scheme is more flexible and intuitive to improve SA, TCO, and MTF values by 50.03%, 45.78%, and 24.7%, respectively.

  11. Aspherical Lens Design Using Genetic Algorithm for Reducing Aberrations in Multifocal Artificial Intraocular Lens

    Directory of Open Access Journals (Sweden)

    Chih-Ta Yen

    2015-09-01

    Full Text Available A complex intraocular lens (IOL design involving numerous uncertain variables is proposed. We integrated a genetic algorithm (GA with the commercial optical design software of (CODE V to design a multifocal IOL for the human eye. We mainly used an aspherical lens in the initial state to the crystalline type; therefore, we used the internal human eye model in the software. The proposed optimized algorithm employs a GA method for optimally simulating the focusing function of the human eye; in this method, the thickness and curvature of the anterior lens and the posterior part of the IOL were varied. A comparison of the proposed GA-designed IOLs and those designed using a CODE V built-in optimal algorithm for 550 degrees myopia and 175 degrees astigmatism conditions of the human eye for pupil size 6 mm showed that the proposed IOL design improved the spot size of root mean square (RMS, tangential coma (TCO and modulation transfer function (MTF at a spatial frequency of 30 with a pupil size of 6 mm by approximately 17%, 43% and 35%, respectively. However, the worst performance of spherical aberration (SA was lower than 46%, because the optical design involves a tradeoff between all aberrations. Compared with the traditional CODE V built-in optimal scheme, the proposed IOL design can efficiently improve the critical parameters, namely TCO, RMS, and MTF.

  12. Bionic optical imaging system with aspheric solid-liquid mixed variable-focus lens

    Science.gov (United States)

    Du, Jia-Wei; Wang, Xuan-Yin; Liang, Dan

    2016-02-01

    A bionic optical imaging system with an aspheric solid-liquid mixed variable-focus lens was designed and fabricated. The entire system mainly consisted of a doublet lens, a solid-liquid mixed variable-focus lens, a connecting part, and a CCD imaging device. To mimic the structure of the crystalline lens, the solid-liquid mixed variable-focus lens consisted of a polydimethylsiloxane (PDMS) lens, a polymethyl methacrylate lens, and the liquid of ethyl silicone oil. By pumping liquid in or out of the cavity using a microinjector, the curvatures of the front and rear surfaces of the PDMS lens were varied, resulting in a change of focal length. The overall structure of the system was presented, as well as a detailed description of the solid-liquid mixed variable-focus lens, material, and fabrication process. Under different injection volumes, the deformation of the PDMS lens was measured and simulated, pictures were captured, and the optical performance was analyzed in simulations and experiments. The focal length of the system ranged from 25.05 to 14.61 mm, and the variation of the diopter was 28.5D, which was larger than that of the human eye.

  13. How do energy stores and changes in these affect departure decisions by migratory birds? A critical view on stopover ecology studies and some future perspectives.

    Science.gov (United States)

    Schmaljohann, Heiko; Eikenaar, Cas

    2017-07-01

    In birds, accumulating energy is far slower than spending energy during flight. During migration, birds spend, therefore, most of the time at stopover refueling energy used during the previous flight. This elucidates why current energy stores and actual rate of accumulating energy are likely crucial factors influencing bird's decision when to resume migration in addition to other intrinsic (sex, age) and extrinsic (predation, weather) factors modulating the decision within the innate migration program. After first summarizing how energy stores and stopover durations are generally determined, we critically review that high-energy stores and low rates of accumulating energy were significantly related to high departure probabilities in several bird groups. There are, however, also many studies showing no effect at all. Recent radio-tracking studies highlighted that migrants leave a site either to resume migration or to search for a better stopover location, so-called "landscape movements". Erroneously treating such movements as departures increases the likelihood of type II errors which might mistakenly suggest no effect of either trait on departure. Furthermore, we propose that energy loss during the previous migratory flight in relation to bird's current energy stores and migration strategy significantly affects its urge to refuel and hence its departure decision.

  14. Aspherical mirrors for the Gamma-ray Cherenkov Telescope, a Schwarschild-Couder prototype proposed for the future Cherenkov Telescope Array

    Science.gov (United States)

    Dournaux, J. L.; Gironnet, J.; Huet, J. M.; Laporte, P.; Chadwick, P.; Dumas, D.; Pech, M.; Rulten, C. B.; Sayède, F.; Schmoll, J.; Sol, H.

    2016-07-01

    The Cherenkov Telescope Array (CTA) project, led by an international collaboration of institutes, aims to create the world's largest next generation Very High-Energy (VHE) gamma-ray telescope array, devoted to observations in a wide band of energy, from a few tens of GeV to more than 100 TeV. The Small-Sized Telescopes (SSTs) are dedicated to the highest energy range. Seventy SSTs are planned in the baseline array design with a required lifetime of about 30 years. The GCT (Gamma-ray Cherenkov Telescope) is one of the prototypes proposed for CTA's SST sub-array. It is based on a Schwarzschild-Couder dual-mirror optical design. This configuration has the benefit of increasing the field-of-view and decreasing the masses of the telescope and of the camera. But, in spite of these many advantages, it was never implemented before in ground-based Cherenkov astronomy because of the aspherical and highly curved shape required for the mirrors. The optical design of the GCT consists of a primary 4 meter diameter mirror, segmented in six aspherical petals, a secondary monolithic 2-meter mirror and a light camera. The reduced number of segments simplifies the alignment of the telescope but complicates the shape of the petals. This, combined with the strong curvature of the secondary mirror, strongly constrains the manufacturing process. The Observatoire de Paris implemented metallic lightweight mirrors for the primary and the secondary mirrors of GCT. This choice was made possible because of the relaxed requirements of optical Cherenkov telescopes compared to optical ones. Measurements on produced mirrors show that these ones can fulfill requirements in shape, PSF and reflectivity, with a clear competition between manufacturing cost and final performance. This paper describes the design of these mirrors in the context of their characteristics and how design optimization was used to produce a lightweight design. The manufacturing process used for the prototype and planned for the

  15. Simulation in Pre-departure Training for Residents Planning Clinical Work in a Low-Income Country

    Directory of Open Access Journals (Sweden)

    Kevin R. Schwartz

    2015-12-01

    Full Text Available Introduction: Increasingly, pediatric and emergency medicine (EM residents are pursuing clinical rotations in low-income countries. Optimal pre-departure preparation for such rotations has not yet been established. High-fidelity simulation represents a potentially effective modality for such preparation. This study was designed to assess whether a pre-departure high-fidelity medical simulation curriculum is effective in helping to prepare residents for clinical rotations in a low-income country. Methods: 43 pediatric and EM residents planning clinical rotations in Liberia, West Africa, participated in a simulation-based curriculum focused on severe pediatric malaria and malnutrition and were then assessed by survey at three time points: pre-simulation, post-simulation, and after returning from work abroad. Results: Prior to simulation, 1/43 (2% participants reported they were comfortable with the diagnosis and management of severe malnutrition; this increased to 30/42 (71% after simulation and 24/31 (77% after working abroad. Prior to simulation, 1/43 (2% of residents reported comfort with the diagnosis and management of severe malaria; this increased to 26/42 (62% after simulation and 28/31 (90% after working abroad; 36/42 (86% of residents agreed that a simulation-based global health curriculum is more useful than a didactic curriculum alone, and 41/42 (98% felt a simulator-based curriculum should be offered to all residents planning a clinical trip to a low-income country. Conclusion: High-fidelity simulation is effective in increasing residents’ self-rated comfort in management of pediatric malaria and malnutrition and a majority of participating residents feel it should be included as a component of pre-departure training for all residents rotating clinically to low-income countries.

  16. The Design and Optimization of an Integrated Arrival/Departure Scheduler Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Intelligent Automation, Inc. (IAI) proposes the design and validation of a dynamic integrated arrival/departure scheduler. In contrast to current approaches, we...

  17. 76 FR 77111 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Science.gov (United States)

    2011-12-12

    ... Federal Aviation Administration 14 CFR Part 97 Standard Instrument Approach Procedures, and Takeoff... Standard Instrument Approach Procedures (SIAPs) and associated Takeoff Minimums and Obstacle Departure... obtained from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters Building, 800 Independence...

  18. 78 FR 7650 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Science.gov (United States)

    2013-02-04

    ... Federal Aviation Administration 14 CFR Part 97 Standard Instrument Approach Procedures, and Takeoff... Standard Instrument Approach Procedures (SIAPs) and associated Takeoff Minimums and Obstacle Departure... from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters Building, 800 Independence Avenue...

  19. The Stiles-Crawford Effect: spot-size ratio departure in retinitis pigmentosa

    Science.gov (United States)

    Sharma, Nachieketa K.; Lakshminarayanan, Vasudevan

    2016-04-01

    The Stiles-Crawford effect of the first kind is the retina's compensative response to loss of luminance efficiency for oblique stimulation manifested as the spot-size ratio departure from the perfect power coupling for a normal human eye. In a retinitis pigmentosa eye (RP), the normal cone photoreceptor morphology is affected due to foveal cone loss and disrupted cone mosaic spatial arrangement with reduction in directional sensitivity. We show that the flattened Stiles-Crawford function (SCF) in a RP eye is due to a different spot-size ratio departure profile, that is, for the same loss of luminance efficiency, a RP eye has a smaller departure from perfect power coupling compared to a normal eye. Again, the difference in spot-size ratio departure increases from the centre towards the periphery, having zero value for axial entry and maximum value for maximum peripheral entry indicating dispersal of photoreceptor alignment which prevents the retina to go for a bigger compensative response as it lacks both in number and appropriate cone morphology to tackle the loss of luminance efficiency for oblique stimulation. The slope of departure profile also testifies to the flattened SCF for a RP eye. Moreover, the discrepancy in spot-size ratio departure between a normal and a RP eye is shown to have a direct bearing on the Stiles-Crawford diminution of visibility.

  20. Assessment of radial aspheres by the Arc-step algorithm as implemented by the Keratron keratoscope.

    Science.gov (United States)

    Tripoli, N K; Cohen, K L; Holmgren, D E; Coggins, J M

    1995-11-01

    To assess the accuracy with which the Keratron (Optikon 2000, Rome, Italy) measured rotationally symmetric, radially aspheric test surfaces according to an arc-step profile reconstruction algorithm and to discriminate between error caused by the algorithm and error from other sources. Height, local power, and axial power calculated from radius of curvature centered on the instrument's axis were reported by the Keratron for four surfaces that had radial profiles similar to normal corneas. The Keratron profile reconstruction algorithm was simulated by using ray tracing. Keratron measurements were compared with the surfaces' formulas and the ray-traced simulations. The heights reported by the Keratron were within 0.25 microns from the four surfaces at less than 3 mm from the keratoscope axis and generally within 1 micron of the height calculated from the surfaces' formulas. The Keratron's axial powers were within +/- 0.1 diopter of the simulation of the axial solution between 1 and 4 mm of the axis but were greater central to 1 mm and peripheral to 4 mm. The Keratron's local powers were within -0.25 diopters at less than 4 mm from the axis and peripherally were between +1.75 diopters and -0.75 diopter of power calculated from the surface's instantaneous radii of curvature. Height error because of the arc-step algorithm was less than -0.2 micron. The Keratron's arc-step profile reconstruction algorithm contributed to its ability to measure height more accurately than keratoscopes that use spherically biased algorithms and provided measurement of local power.

  1. Assessment of the power and height of radial aspheres reported by a computer-assisted keratoscope.

    Science.gov (United States)

    Cohen, K L; Tripoli, N K; Holmgren, D E; Coggins, J M

    1995-06-01

    The two purposes of this study were (a) to assess the accuracy with which a keratoscope, the Topographic Modeling System (TMS-1), calculated the heights and powers of rotationally symmetric, radially aspheric test surfaces and (b) to determine whether the TMS-1 used an axial solution for radius of curvature to determine the power of a sphere that would produce the same semichord as would the test surface on a keratograph. The TMS-1 heights and powers were studied for four test surfaces that had radial profiles similar to those of normal corneas. The powers of the surfaces were calculated from the local radius of curvature derived from the surfaces' manufacturing formulas. The heights and powers that would result from an axial solution were calculated in a TMS-1 simulator. TMS-1 data were compared with data from the surfaces' formulas and with data from the simulation. The TMS-1 data were almost identical to the heights and powers calculated from the simulated axial solution. The TMS-1 data were similar to the heights and powers calculated from the mathematical formulas from the apex to 2 mm from the apex but differed by up to 85 microns of height and 10 diopters of power in the periphery. The TMS-1 appeared to use the axial solution that does not calculate power from local radius of curvature. Clinicians should use caution when inferring corneal shape from power maps based on an axial solution, especially outside the central 2-mm radius of a normal cornea, because such power does not depict corneal curvature.

  2. Corneal Epithelial Remodeling and Its Effect on Corneal Asphericity after Transepithelial Photorefractive Keratectomy for Myopia

    Directory of Open Access Journals (Sweden)

    Jie Hou

    2016-01-01

    Full Text Available Purpose. To evaluate the changes in epithelial thickness profile following transepithelial photorefractive keratectomy (T-PRK for myopia and to investigate the effect of epithelial remodeling on corneal asphericity. Methods. Forty-four patients (44 right eyes who underwent T-PRK were retrospectively evaluated. Epithelial thickness was measured using spectral-domain optical coherence tomography at different corneal zones (central, 2 mm; paracentral, 2–5 mm; and mid-peripheral, 5-6 mm preoperatively and at 1 week and 1, 3, and 6 months postoperatively. The correlation between the changes in corneal epithelial thickness (ΔCET and postoperative Q-value changes (ΔQ was analyzed 6 months postoperatively. Results. Epithelial thickness at 6 months showed a negative meniscus-like lenticular pattern with less central thickening, which increased progressively toward the mid-periphery (3.69±4.2, 5.19±3.8, and 6.23±3.9 μm at the center, paracenter, and mid-periphery, resp., P<0.01. A significant positive relationship was observed between epithelial thickening and ΔQ 6 months postoperatively (r=0.438, 0.580, and 0.504, resp., P<0.01. Conclusions. Significant epithelial thickening was observed after T-PRK and showed a lenticular change with more thickening mid-peripherally, resulting in increased oblateness postoperatively. Epithelial remodeling may modify the epithelial thickness profile after surface ablation refractive surgery for myopia.

  3. Correlations between the alpha angle and femoral head asphericity: Implications and recommendations for the diagnosis of cam femoroacetabular impingement

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Michael D., E-mail: michael.harris@utah.edu [Department of Orthopaedics, Department of Bioengineering, University of Utah, 590 Wakara Way A-100, Salt Lake City, UT 84108 (United States); Kapron, Ashley L., E-mail: ashley.kapron@utah.edu [Department of Orthopaedics, Department of Bioengineering, University of Utah, 590 Wakara Way A-100, Salt Lake City, UT 84108 (United States); Peters, Christopher L., E-mail: chris.peters@hsc.utah.edu [Department of Orthopaedics, 590 Wakara Way A-100, Salt Lake City, UT 84108 (United States); Anderson, Andrew E., E-mail: andrew.anderson@hsc.utah.edu [Department of Orthopaedics, Department of Bioengineering, Department of Physical Therapy, Scientific Computing and Imaging Institute, University of Utah, 590 Wakara Way A-100, Salt Lake City, UT 84108 (United States)

    2014-05-15

    Objective: To determine the strength of common radiographic and radial CT views for measuring true femoral head asphericity. Patients and methods: In 15 patients with cam femoroacetabular impingement (FAI) and 15 controls, alpha angles were measured by two observers using radial CT (0°, 30°, 60°, 90°) and digitally reconstructed radiographs (DRRs) for the: anterior–posterior (AP), standing frog-leg lateral, 45° Dunn with neutral rotation, 45° Dunn with 40° external rotation, and cross-table lateral views. A DRR validation study was performed. Alpha angles were compared between groups. Maximum deviation from a sphere of each subject was obtained from a previous study. Alpha angles from each view were correlated with maximum deviation. Results: There were no significant differences between alpha angles measured on radiographs and the corresponding DRRs (p = 0.72). Alpha angles were significantly greater in patients for all views (p ≤ 0.002). Alpha angles from the 45° Dunn with 40° external rotation, cross-table lateral, and 60° radial views had the strongest correlations with maximum deviation (r = 0.831; r = 0.823; r = 0.808, respectively). The AP view had the weakest correlation (r = 0.358). Conclusion: DRRs were a validated means to simulate hip radiographs. The 45° Dunn with 40° external rotation, cross-table lateral, and 60° radial views best visualized femoral asphericity. Although commonly used, the AP view did not visualize cam deformities well. Overall, the magnitude of the alpha angle may not be indicative of the size of the deformity. Thus, 3D reconstructions and measurements of asphericity could improve the diagnosis of cam FAI.

  4. Clinical Evaluation of Functional Vision of +1.5 Diopters near Addition, Aspheric, Rotational Asymmetric Multifocal Intraocular Lens

    Science.gov (United States)

    Khoramnia, Rahmin; Attia, Mary Safwat; Koss, Michael Janusz; Linz, Katharina; Auffarth, Gerd Uwe

    2016-01-01

    Purpose To evaluate postoperative outcomes and visual performance in intermediate distance after implantation of a +1.5 diopters (D) addition, aspheric, rotational asymmetric multifocal intraocular lens (MIOL). Methods Patients underwent bilateral cataract surgery with implantation of an aspheric, asymmetric MIOL with +1.5 D near addition. A complete ophthalmological examination was performed preoperatively and 3 months postoperatively. The main outcome measures were monocular and binocular uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), distance corrected intermediate visual acuity (DCIVA), uncorrected near visual acuity (UNVA) and distance corrected keratometry, and manifest refraction. The Salzburg Reading Desk was used to analyze unilateral and bilateral functional vision with uncorrected and corrected reading acuity, reading distance, reading speed, and the smallest log-scaled print size that could be read effectively at near and intermediate distances. Results The study comprised 60 eyes of 30 patients (mean age, 68.30 ± 9.26 years; range, 34 to 80 years). There was significant improvement in UDVA and CDVA. Mean UIVA was 0.01 ± 0.09 logarithm of the minimum angle of resolution (logMAR) and mean DCIVA was -0.02 ± 0.11 logMAR. In Salzburg Reading Desk analysis for UIVA, the mean subjective intermediate distance was 67.58 ± 8.59 cm with mean UIVA of -0.02 ± 0.09 logMAR and mean word count of 96.38 ± 28.32 words/min. Conclusions The new aspheric, asymmetric, +1.5 D near addition MIOL offers good results for distance visual function in combination with good performance for intermediate distances and functional results for near distance. PMID:27729759

  5. Revival of The Stalled Core-Collapse Supernova Shock Triggered by Precollapse Asphericity in the Progenitor Star

    CERN Document Server

    Couch, Sean M

    2013-01-01

    Multi-dimensional simulations of advanced nuclear burning stages of massive stars suggest that the Si/O layers of presupernova stars harbor large deviations from the spherical symmetry typically assumed for presupernova stellar structure. We carry out three-dimensional core-collapse supernova simulations with and without aspherical velocity perturbations to assess their potential impact on the supernova hydrodynamics in the stalled shock phase. Our results show that realistic perturbations can qualitatively alter the postbounce evolution, triggering an explosion in a model that fails to explode without them. This finding underlines the need for a multi-dimensional treatment of the presupernova stage of stellar evolution.

  6. Relaxing the closure assumption in single-season occupancy models: staggered arrival and departure times

    Science.gov (United States)

    Kendall, William L.; Hines, James E.; Nichols, James D.; Grant, Evan H. Campbell

    2013-01-01

    Occupancy statistical models that account for imperfect detection have proved very useful in several areas of ecology, including species distribution and spatial dynamics, disease ecology, and ecological responses to climate change. These models are based on the collection of multiple samples at each of a number of sites within a given season, during which it is assumed the species is either absent or present and available for detection while each sample is taken. However, for some species, individuals are only present or available for detection seasonally. We present a statistical model that relaxes the closure assumption within a season by permitting staggered entry and exit times for the species of interest at each site. Based on simulation, our open model eliminates bias in occupancy estimators and in some cases increases precision. The power to detect the violation of closure is high if detection probability is reasonably high. In addition to providing more robust estimation of occupancy, this model permits comparison of phenology across sites, species, or years, by modeling variation in arrival or departure probabilities. In a comparison of four species of amphibians in Maryland we found that two toad species arrived at breeding sites later in the season than a salamander and frog species, and departed from sites earlier.

  7. Modeling of the New Machining Methods for Ultra-Precision Axisymmetric Aspheric Mirrors%轴对称非球面镜超精密加工新方法的几何模型

    Institute of Scientific and Technical Information of China (English)

    韩成顺; 张龙江; 董国军; 李国; 董申

    2006-01-01

    A new form generation method for ultra-precision axisymmetric aspheric mirrors is introduced. Linear motion guides are employed in the feed systems of most diamond turning machines. For rotary axes can be made less expensive,easier and more compact than a linear guide at the same precision level, a rotary arm that carries a diamond tool combined with a fast tool servo are used to replace the straight lines. The micro linear feed of the fast tool servo is real-time calculated with the use high resolution angular feedback on the swing tool based on the aspheric equation. Synchronized motion of the the fast tool servo, workpiece and the diamond tool produces ultra-precision axisymmetric aspheric mirrors. Geometric models of cutting tool path, the motion of fast tool servo and the corresponding calculations are presented. The machining approach is verified to be simple and reliable by computer simulation, so the production efficiency can be improved and the equipment input can be reduced.%介绍了轴对称光学非球面镜超精密加工的新方法.超精密金刚石切削加工机床的刀具进给机构通常由直线导轨实现.由于旋转轴与同等精度的直线导轨相比,具有制造难度小、成本低及结构紧凑等优点,所以采用具有快速伺服机构的金刚石刀架摆臂代替直线导轨进给运动方式.根据非球面方程,快速伺服机构的微进给量根据车刀摆角实时计算.快速伺服机构、工件以及金刚石刀具的同时运动,可以实现轴对称非球面的超精密加工.构建了回转进给工具路径、快速伺服机构运动以及相关的几何模型.通过计算机模拟验证了该加工方法的简便与可靠性,可以降低非球面反射镜加工的设备投入,提高生产效率.

  8. Contact mechanics and elastohydrodynamic lubrication in a novel metal-on-metal hip implant with an aspherical bearing surface.

    Science.gov (United States)

    Meng, Qingen; Gao, Leiming; Liu, Feng; Yang, Peiran; Fisher, John; Jin, Zhongmin

    2010-03-22

    Diameter and diametral clearance of the bearing surfaces of metal-on-metal hip implants and structural supports have been recognised as key factors to reduce the dry contact and hydrodynamic pressures and improve lubrication performance. On the other hand, application of aspherical bearing surfaces can also significantly affect the contact mechanics and lubrication performance by changing the radius of the curvature of a bearing surface and consequently improving the conformity between the head and the cup. In this study, a novel metal-on-metal hip implant employing a specific aspherical bearing surface, Alpharabola, as the acetabular surface was investigated for both contact mechanics and elastohydrodynamic lubrication under steady-state conditions. When compared with conventional spherical bearing surfaces, a more uniform pressure distribution and a thicker lubricant film thickness within the loaded conjunction were predicted for this novel Alpharabola hip implant. The effects of the geometric parameters of this novel acetabular surface on the pressure distribution and lubricant thickness were investigated. A significant increase in the predicted lubricant film thickness and a significant decrease in the dry contact and hydrodynamic pressures were found with appropriate combinations of these geometric parameters, compared with the spherical bearing surface.

  9. Numerical simulation of the optical characteristics of autostereoscopic displays that have an aspherical lens array with a slanted angle.

    Science.gov (United States)

    Jung, Sung-Min; Kang, In-Byeong

    2014-02-10

    We developed a 3D simulation model describing the optical phenomena on a slanted lenticular surface with aspherical lenses for autostereoscopic displays and analyzed the optical behavior of the multiview autostereoscopic display under actual design conditions by using a 3D simulation model. Optical characteristics, such as 3D crosstalk and 3D luminance differences, are obtained from the simulation of the light distribution for the multiview autostereoscopic displays with slated angles of 0.0°, 9.46°, 12.59°, and 14.04°. By investigating the effect of the conic constant of an aspherical lens surface on the 3D crosstalk and the 3D luminance differences for given several design conditions, we find the optimal values of the conic constant for slanted angles of 0.0° and 9.46° in order to minimize the 3D crosstalk and the 3D luminance difference. From these results, we think that our simulation model is very useful for designing the lens array to optimize the optical characteristics of autostereoscopic displays.

  10. Ground-based and orbital off-axis aspherized grating imager-spectrographs: ISARD-OMP and OSIRIS-ODIN

    Science.gov (United States)

    Lemaitre, Gerard R.; Richardson, Eric H.

    1998-07-01

    Progress in Active Optics Methods has led to the invention and production of blazed aspherical gratings. These developments use jointly 'vase form' submasters and a two-stage replication technique. It has been shown that the use of aspherized gratings greatly minimizes the number of optical surfaces. This improves the optical throughput of astronomical spectrographs and has a capability of correcting camera mirror aberrations up to f/1.2. With respect to refractive designs, the full achromaticity in correcting mirror aberrations by constant line spacing reflective gratings allows much broader spectral coverages -- hereafter [(lambda) (lambda) ] approximately equals 2 octaves. In addition, and also due to a full reflective design, such instruments provide quasi- constant spectral dispersions and are distortion free. These latter features increase the accuracy in the data reduction process (sky substraction, etc. ...), and are particularly convenient in the multi-aperture mode. Recent developments in this field are presented with imager-spectrograph ISARD, dedicated to the Cassegrain focus of the 2m Bernard Lyot Telescope at Pic-du-Midi Observatory for faint object studies in the optical domain [320 - 1200 nm], and with spectrograph OSIRIS, to be launched in a ODIN orbital mission in 1998 and built by the Canadian Space Agency for studies in the spectral range [295 - 800 nm].

  11. Transferable aspherical atom model refinement of protein and DNA structures against ultrahigh-resolution X-ray data.

    Science.gov (United States)

    Malinska, Maura; Dauter, Zbigniew

    2016-06-01

    In contrast to the independent-atom model (IAM), in which all atoms are assumed to be spherical and neutral, the transferable aspherical atom model (TAAM) takes into account the deformed valence charge density resulting from chemical bond formation and the presence of lone electron pairs. Both models can be used to refine small and large molecules, e.g. proteins and nucleic acids, against ultrahigh-resolution X-ray diffraction data. The University at Buffalo theoretical databank of aspherical pseudo-atoms has been used in the refinement of an oligopeptide, of Z-DNA hexamer and dodecamer duplexes, and of bovine trypsin. The application of the TAAM to these data improves the quality of the electron-density maps and the visibility of H atoms. It also lowers the conventional R factors and improves the atomic displacement parameters and the results of the Hirshfeld rigid-bond test. An additional advantage is that the transferred charge density allows the estimation of Coulombic interaction energy and electrostatic potential.

  12. The asphericity of the metabolic tumour volume in NSCLC: correlation with histopathology and molecular markers

    Energy Technology Data Exchange (ETDEWEB)

    Apostolova, Ivayla; Ego, Kilian; Steffen, Ingo G. [University Hospital, Otto-von-Guericke University Magdeburg, Clinic of Radiology and Nuclear Medicine, Magdeburg (Germany); Buchert, Ralph [University Medicine Charite, Clinic of Nuclear Medicine, Berlin (Germany); Wertzel, Heinz; Achenbach, H.J. [Lung Clinic Lostau GmbH, Lostau (Germany); Riedel, Sandra; Schreiber, Jens [University Hospital, Otto-von-Guericke University Magdeburg, Clinic of Pneumology, Magdeburg (Germany); Schultz, Meinald [Institute of Pathology Stendal, Stendal (Germany); Furth, Christian; Amthauer, Holger [University Hospital, Otto-von-Guericke University Magdeburg, Clinic of Radiology and Nuclear Medicine, Magdeburg (Germany); University Medicine Charite, Clinic of Nuclear Medicine, Berlin (Germany); Derlin, Thorsten [Hannover Medical School, Department of Nuclear Medicine, Hannover (Germany); Hofheinz, Frank [Helmholtz-Center Dresden-Rossendorf, Dresden (Germany); Kalinski, Thomas [University Hospital Magdeburg, Otto-von-Guericke University Magdeburg, Institute for Pathology, Magdeburg (Germany); Institute for Pathology Lademannbogen, Hamburg (Germany)

    2016-12-15

    Asphericity (ASP) is a tumour shape descriptor based on the PET image. It quantitates the deviation from spherical of the shape of the metabolic tumour volume (MTV). In order to identify its biological correlates, we investigated the relationship between ASP and clinically relevant histopathological and molecular signatures in non-small-cell lung cancer (NSCLC). The study included 83 consecutive patients (18 women, aged 66.4 ± 8.9 years) with newly diagnosed NSCLC in whom PET/CT with {sup 18}F-FDG had been performed prior to therapy. Primary tumour resection specimens and core biopsies were used for basic histopathology and determination of the Ki-67 proliferation index. EGFR status, VEGF, p53 and ALK expression were obtained in a subgroup of 44 patients. The FDG PET images of the primary tumours were delineated using an automatic algorithm based on adaptive thresholding taking into account local background. In addition to ASP, SUVmax, MTV and some further descriptors of shape and intratumour heterogeneity were assessed as semiquantitative PET measures. SUVmax, MTV and ASP were associated with pathological T stage (Kruskal-Wallis, p = 0.001, p < 0.0005 and p < 0.0005, respectively) and N stage (p = 0.017, p = 0.003 and p = 0.002, respectively). Only ASP was associated with M stage (p = 0.026). SUVmax, MTV and ASP were correlated with Ki-67 index (Spearman's rho = 0.326/p = 0.003, rho = 0.302/p = 0.006 and rho = 0.271/p = 0.015, respectively). The latter correlations were considerably stronger in adenocarcinomas than in squamous cell carcinomas. ASP, but not SUVmax or MTV, showed a tendency for a significant association with the extent of VEGF expression (p = 0.058). In multivariate Cox regression analysis, ASP (p < 0.0005) and the presence of distant metastases (p = 0.023) were significantly associated with progression-free survival. ASP (p = 0.006), the presence of distant metastases (p = 0.010), and Ki-67 index (p = 0.062) were significantly associated with

  13. A modified force-balance model for prediction of bubble departure diameter in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Sugrue, R., E-mail: rsugrue@mit.edu; Buongiorno, J.

    2016-08-15

    Highlights: • Existing bubble departure models were tested against various experimental databases. • General experimental trends were captured correctly but give large average errors. • A modified bubble departure model is proposed and tested against these databases. - Abstract: Experimental data by Sugrue et al., Klausner et al., Zeng et al., Prodanovic et al., and Situ et al. for bubble departure diameter in subcooled flow boiling in a wide range of orientation angle, subcooling, heat flux, mass flux, and pressure conditions were used to assess the predictive accuracy of the mechanistic force-balance models of Klausner et al. and Yun et al. The results suggested that both models capture the experimental trends correctly, but exhibit large average errors and standard deviations, i.e. 85.5% (σ = 49.7%) and 43.9% (σ = 23.1%) for Klausner’s and Yun’s models, respectively. Since the cube of the bubble departure diameter is used in subcooled flow boiling heat transfer models, such errors are unacceptable, and underscore the need for greater accuracy in predictions. Therefore, the databases were used to (i) identify the dominant forces determining bubble departure at various operating conditions, and (ii) optimize the empirical coefficients describing those forces in Klausner’s model. The modified model considerably lowers prediction error to 22.4% (σ = 19.9%) for all data considered. Application of the modified model is demonstrated for the subcooled flow boiling conditions present in the hot channel of a typical Pressurized Water Reactor (PWR).

  14. Collaborative Virtual Queue: Fair Management of Congested Departure Operations and Benefit Analysis

    CERN Document Server

    Burgain, Pierrick; Clarke, John-Paul

    2008-01-01

    Due to the stochastic nature of departure operations, working at full capacity makes major US airports very sensitive to uncertainties. Consequently, airport ground operations face critically congested taxiways and long runway queues. In this report, we show how improved management of departure operations from the ready-to-push-back time to the wheels-off time can potentially yield significant benefits to airlines and air traffic services. We develop a Collaborative Virtual Queue to enable better optimization capabilities during congested situations while taking into account the laissez-faire competitive environment. Results are evaluated using a departure system model, validated using current statistics and previous studies. First, the Collaborative Virtual Queue enables keeping aircraft away from runway queues, which increases wheels-off time predictability. Second, holding aircraft enables last-minute intra-airline flight switching. This creates new optimization capabilities for airlines i.e. it gives airl...

  15. Precision Departure Release Capability (PDRC) Overview and Results: NASA to FAA Research Transition

    Science.gov (United States)

    Engelland, Shawn; Davis, Tom.

    2013-01-01

    NASA researchers developed the Precision Departure Release Capability (PDRC) concept to improve the tactical departure scheduling process. The PDRC system is comprised of: 1) a surface automation system that computes ready time predictions and departure runway assignments, 2) an en route scheduling automation tool that uses this information to estimate ascent trajectories to the merge point and computes release times and, 3) an interface that provides two-way communication between the two systems. To minimize technology transfer issues and facilitate its adoption by TMCs and Frontline Managers (FLM), NASA developed the PDRC prototype using the Surface Decision Support System (SDSS) for the Tower surface automation tool, a research version of the FAA TMA (RTMA) for en route automation tool and a digital interface between the two DSTs to facilitate coordination.

  16. Extracting message inter-departure time distributions from the human electroencephalogram.

    Directory of Open Access Journals (Sweden)

    Bratislav Mišić

    2011-06-01

    Full Text Available The complex connectivity of the cerebral cortex is a topic of much study, yet the link between structure and function is still unclear. The processing capacity and throughput of information at individual brain regions remains an open question and one that could potentially bridge these two aspects of neural organization. The rate at which information is emitted from different nodes in the network and how this output process changes under different external conditions are general questions that are not unique to neuroscience, but are of interest in multiple classes of telecommunication networks. In the present study we show how some of these questions may be addressed using tools from telecommunications research. An important system statistic for modeling and performance evaluation of distributed communication systems is the time between successive departures of units of information at each node in the network. We describe a method to extract and fully characterize the distribution of such inter-departure times from the resting-state electroencephalogram (EEG. We show that inter-departure times are well fitted by the two-parameter Gamma distribution. Moreover, they are not spatially or neurophysiologically trivial and instead are regionally specific and sensitive to the presence of sensory input. In both the eyes-closed and eyes-open conditions, inter-departure time distributions were more dispersed over posterior parietal channels, close to regions which are known to have the most dense structural connectivity. The biggest differences between the two conditions were observed at occipital sites, where inter-departure times were significantly more variable in the eyes-open condition. Together, these results suggest that message departure times are indicative of network traffic and capture a novel facet of neural activity.

  17. Identifying Key Issues and Potential Solutions for Integrated Arrival, Departure, Surface Operations by Surveying Stakeholder Preferences

    Science.gov (United States)

    Aponso, Bimal; Coppenbarger, Richard A.; Jung, Yoon; Quon, Leighton; Lohr, Gary; O’Connor, Neil; Engelland, Shawn

    2015-01-01

    NASA's Aeronautics Research Mission Directorate (ARMD) collaborates with the FAA and industry to provide concepts and technologies that enhance the transition to the next-generation air-traffic management system (NextGen). To facilitate this collaboration, ARMD has a series of Airspace Technology Demonstration (ATD) sub-projects that develop, demonstrate, and transitions NASA technologies and concepts for implementation in the National Airspace System (NAS). The second of these sub-projects, ATD-2, is focused on the potential benefits to NAS stakeholders of integrated arrival, departure, surface (IADS) operations. To determine the project objectives and assess the benefits of a potential solution, NASA surveyed NAS stakeholders to understand the existing issues in arrival, departure, and surface operations, and the perceived benefits of better integrating these operations. NASA surveyed a broad cross-section of stakeholders representing the airlines, airports, air-navigation service providers, and industry providers of NAS tools. The survey indicated that improving the predictability of flight times (schedules) could improve efficiency in arrival, departure, and surface operations. Stakeholders also mentioned the need for better strategic and tactical information on traffic constraints as well as better information sharing and a coupled collaborative planning process that allows stakeholders to coordinate IADS operations. To assess the impact of a potential solution, NASA sketched an initial departure scheduling concept and assessed its viability by surveying a select group of stakeholders for a second time. The objective of the departure scheduler was to enable flights to move continuously from gate to cruise with minimal interruption in a busy metroplex airspace environment using strategic and tactical scheduling enhanced by collaborative planning between airlines and service providers. The stakeholders agreed that this departure concept could improve schedule

  18. Development of an aspheric 22-diopter 50-mm diameter magnifier Desenvolvimento de uma lupa asférica de 22 dioptrias de 50 mm de diâmetro

    Directory of Open Access Journals (Sweden)

    José Américo Bonatti

    2008-04-01

    Full Text Available PURPOSE: To develop in an interdisciplinary approach between ophthalmology and design areas an ergonomic +22-diopter 50-mm aspheric hand magnifier for low vision. METHODS: An aluminum cylinder was cut, processed using a lathe and carved to produce a ring that accommodated a 50-mm aspheric lens, with an external depression not to slide from the holder's fingers. A cylindrical steel bar was cut, processed using a lathe and carved in order to form an externally turned ring to be screwed into the internal thread of the aluminum ring, to maintain the lens in a steady position. Both rings were submitted to electrostatic painting with a dull black electrostatic Epoxi ink, except the lower border of the external ring, to indicate the correct side of the magnifier to face the material to be read. RESULTS: A 22-diopter 50-mm diameter aspheric lens magnifier with a black ring to be hold at its external circular depression was obtained in order to safely search the adequate reading focus with an inferior aluminum colored ring to face the object to be read and allow a less distorted reading. This is the first Brazilian high-magnification great-diameter magnifier for low vision that permits basically the focusing on an entire word, not only syllables, in order to allow a faster and more comfortable reading. CONCLUSIONS: By an interdisciplinary approach a 22-diopter 50-mm aspheric lens magnifier was developed with image and ergonomic characteristics such as to permit comfortable and adequate reading performance in cases of low vision.OBJETIVO: Desenvolver de modo interdisciplinar entre as áreas de oftalmologia e design uma lupa de mão ergonômica de +22 dioptrias de 50 mm de diâmetro asférica para baixa visão. MÉTODOS: Um cilindro de alumínio foi cortado, torneado e teve feita internamente uma rosca a fim de produzir um anel para acomodar uma lente asférica de 50 mm de diâmetro com uma depressão externa para não escorregar dos dedos do portador. Uma

  19. 非球面数控研抛力-位-姿解耦控制研究%Research on Force-position-posture Decoupling Control for NC Polishing of Aspheric Parts

    Institute of Scientific and Technical Information of China (English)

    史永杰; 郑堤; 詹建明; 王龙山

    2011-01-01

    In order to resolve the problem of force-position-posture coupling in automatic polishing systems and improve the polishing quality of aspheric part surface, a new decoupling control method for NC polishing based on magnetorheological torque servo (MRT) is proposed. Theoretical and experimental studies on the principle and model of this method are carried out. After a deep investigation into the coupling mechanism, the model of force-position-posture coupling is established based on Preston equation and Hertz theory, the principle of force-position-posture decoupling based on the MRT is introduced, the control models of polishing force and rotational speed of aspheric parts are deduced, and a corresponding experimental system is developed. Experiments are carried out, and mirror-like aspheric part surface with a roughness of Ra≤0.030 μm as well as constant material removal rates are obtained.Research results show that the MRT-based decoupling method can effectively resolve the problem of force-position-posture coupling,and provides a new way to achieve NC polishing of aspheric parts with high quality and efficiency and low cost.%为解决自动研抛系统中研抛力-研抛头位置-研抛头姿态之间的耦合问题,提高非球面表面的研抛质量,提出一种基于磁流变力矩伺服装置(Magnetorheologicalfluidtorque servo,MRT)的力-位-姿解耦控制方法,并对该方法的原理和模型进行理论和试验研究.通过分析自动研抛系统中力-位-姿之间的耦合机理,以Preston方程和Hertz接触理论为基础,建立力-位-姿耦合模型,探讨基于MRT的力-位-姿解耦原理,推导出基于MRT的研抛力控制模型和数控机床转速控制模型,研制相应的试验系统,并通过研抛试验得到表面粗糙度Ra≤0.030μm的镜面表面和均匀的材料去除率.研究结果表明,基于MRT的力-位-姿解耦控制方法,能够有效地解决研抛系统中力-位-姿耦合难题,是实现非球面高精度、

  20. Asphericity, Interaction, and Dust in the Type II-P/II-L Supernova 2013ej in Messier 74

    CERN Document Server

    Mauerhan, Jon C; Johansson, Joel; Hu, Maokai; Fox, Ori D; Wang, Lifan; Graham, Melissa L; Filippenko, Alexei V; Shivvers, Isaac

    2016-01-01

    SN 2013ej is a well-studied core-collapse supernova (SN) that stemmed from a directly identified red supergiant (RSG) progenitor in galaxy M74. The source exhibits signs of substantial geometric asphericity, X-rays from persistent interaction with circumstellar material (CSM), thermal emission from warm dust, and a light curve that appears intermediate between supernovae of Types II-P and II-L. The proximity of this source motivates a close inspection of these physical characteristics and their potential interconnection. We present multi-epoch spectropolarimetry of SN 2013ej during the first 107 days, and deep optical spectroscopy and ultraviolet through infrared photometry past ~800 days. SN 2013ej exhibits the strongest and most persistent continuum and line polarization ever observed for a SN of its class during the recombination phase. Modeling indicates that the data are consistent with an oblate ellipsoidal photosphere, viewed nearly edge-on, and probably augmented by optical scattering from circumstell...

  1. Asphericity in the Fermi Surface and Fermi Energy of Na-K,Na-Rb and Na-Cs Binary Alloys

    Institute of Scientific and Technical Information of China (English)

    MinalH.Patel; A.M.Vora; 等

    2002-01-01

    Detailed theoretical investigations into asphericity in the Fermi surface(FS) and Fermi energy(FE) of Na1-xKx,Na1-xRbx,and Na1-xCsx binary solid solutions are carried out for the first time,The allying behavior of the K,Rb,and Cs with the Na generates the Fermi surface distortion(FSD) of bcc simple metals,The FS of Na-K,Na-Rb,and Na-Cs solid solution is a distorted sphere with the largest deviation along[110],We have found that the impact of local-field correction function on FSD is maximum at [100] point and minimum at [111] point.The exchange and correlation effect is found to suppress the value of FE.

  2. Asphericity, Interaction, and Dust in the Type II-P/II-L Supernova 2013EJ in Messier 74

    Science.gov (United States)

    Mauerhan, Jon C.; Van Dyk, Schuyler D.; Johansson, Joel; Hu, Maokai; Fox, Ori D.; Wang, Lifan; Graham, Melissa L.; Filippenko, Alexei V.; Shivvers, Isaac

    2017-01-01

    SN 2013ej is a well-studied core-collapse supernova (SN) that stemmed from a directly identified red supergiant (RSG) progenitor in galaxy M74. The source exhibits signs of substantial geometric asphericity, X-rays from persistent interaction with circumstellar material (CSM), thermal emission from warm dust, and a light curve that appears intermediate between supernovae of Types II-P and II-L. The proximity of this source motivates a close inspection of these physical characteristics and their potential interconnection. We present multiepoch spectropolarimetry of SN 2013ej during the first 107 days and deep optical spectroscopy and ultraviolet through infrared photometry past ∼800 days. SN 2013ej exhibits the strongest and most persistent continuum and line polarization ever observed for a SN of its class during the recombination phase. Modeling indicates that the data are consistent with an oblate ellipsoidal photosphere, viewed nearly edge-on and probably augmented by optical scattering from circumstellar dust. We suggest that interaction with an equatorial distribution of CSM, perhaps the result of binary evolution, is responsible for generating the photospheric asphericity. Relatedly, our late-time optical imaging and spectroscopy show that asymmetric CSM interaction is ongoing, and the morphology of broad Hα emission from shock-excited ejecta provides additional evidence that the geometry of the interaction region is ellipsoidal. Alternatively, a prolate ellipsoidal geometry from an intrinsically bipolar explosion is also a plausible interpretation of the data but would probably require a ballistic jet of radioactive material capable of penetrating the hydrogen envelope early in the recombination phase. Finally, our latest space-based optical imaging confirms that the late interaction-powered light curve dropped below the stellar progenitor level, confirming the RSG star’s association with the explosion.

  3. Visual acuity and patient satisfaction at varied distances and lighting conditions after implantation of an aspheric diffractive multifocal one-piece intraocular lens

    Science.gov (United States)

    Chang, Daniel H

    2016-01-01

    Purpose The aim of the study is to evaluate the visual acuity and patient satisfaction at varied distances under photopic and mesopic lighting conditions in patients bilaterally implanted with aspheric diffractive multifocal one-piece intraocular lenses. Methods In this retrospective–prospective study, 16 patients with a mean age of 66.2±9.2 years (range: 50–81 years) who had undergone bilateral phacoemulsification surgery with implantation of a Tecnis multifocal one-piece intraocular lens (ZMB00) were evaluated. Monocular and binocular uncorrected and distance-corrected visual acuities were measured at distance (20 ft), intermediate (70–80 cm), and near (35–40 cm) under photopic (85 cd/m2) and mesopic (3 cd/m2) lighting conditions and were compared using the paired t-test. All patients also completed a subjective questionnaire. Results At a mean follow-up of 9.5±3.9 months, distance, near, and intermediate visual acuity improved significantly from preoperative acuity. Under photopic and mesopic conditions, 93.8% and 62.5% of patients, respectively, had binocular uncorrected intermediate visual acuity of 20/40 or better, and 62.5% and 31.3% of patients had binocular uncorrected near visual acuity of 20/20 or better. All patients were satisfied with their overall vision without using glasses and/or contact lenses when compared with before surgery. A total of 87.5% of patients reported no glare and 68.8% of patients reported no halos around lights at night. Conclusion Tecnis multifocal one-piece intraocular lenses provide good distance, intermediate, and near visual acuity under photopic as well as mesopic lighting conditions. High levels of spectacle independence with low levels of photic phenomenon were achieved, resulting in excellent patient satisfaction. PMID:27536061

  4. 76 FR 5058 - Airports of Entry or Departure for Flights to and From Cuba

    Science.gov (United States)

    2011-01-28

    ... or Departure for Flights to and From Cuba AGENCY: U.S. Customs and Border Protection, DHS. ACTION... United States and Cuba must arrive at or depart from one of three named U.S. airports: John F. Kennedy... the United States and Cuba. These amendments are in accordance with the President's recent...

  5. Methodology for Performance Evaluation of Pre Departure Sequencing Tools in terms of A-CDM concept

    Directory of Open Access Journals (Sweden)

    Hynek Hrabík

    2017-01-01

    Full Text Available The article describes the proposed methodology for performance evaluation of Pre-Departure Sequencing tools. Pre-departure management delivers optimal traffic flow to the runway by route planning and accurate taxi time forecasts. Firstly, a Pre-Departure Sequencer Start-Up Manager (SUM used by Air Navigation Services of the Czech Republic (ANS CZ at Vaclav Havel Airport Prague (LKPR is mentioned. The main parts deal with the proposed methodology for performance evaluation of Start-Up Manager. The methodology uses several indicators to evaluate the performance. The methodology utilizes time milestones introduced in Airport Collaborative Decision Making (A-CDM concept. It focuses especially on aircraft pre-departure sequencing processes. Methodology was tested on the Start-Up Manager used by Air Navigation Services (ANS of the Czech Republic at Vaclav Havel Airport Prague (LKPR. Achieved performance results and its credibility in accordance with the proposed methodology are presented and discussed in the final part of this paper.

  6. Ray Tracing Results for Elevation Angle Spread of Departure and its Impact on System Performance

    DEFF Research Database (Denmark)

    Mondal, Bishwarup; Thomas, Timothy; Nguyen, Huan Cong

    2014-01-01

    Elevation spread of departure angles (ESD) is the key parameter characterizing a 3D fast-fading channel model. 3D channel mod-eling is currently being studied in 3GPP to enable the develop-ment of MIMO techniques exploiting both azimuth and elevation dimensions of the channel. In this paper we us...

  7. 8 CFR 1240.26 - Voluntary departure-authority of the Executive Office for Immigration Review.

    Science.gov (United States)

    2010-01-01

    ... removability; (D) Waives appeal of all issues; and (E) Has not been convicted of a crime described in section... section 239(a) of the Act; (ii) The alien is, and has been, a person of good moral character for at least... business days of the immigration judge's order granting voluntary departure. (ii) An alien who has been...

  8. Accounting for the Theory of Planned Behaviour in departure time choice

    DEFF Research Database (Denmark)

    Thorhauge, Mikkel; Haustein, Sonja; Cherchi, Elisabetta

    2016-01-01

    choice. So far departure time choice modelling focussed mainly on objective factors, such as time and costs as main behavioural determinants. In this study, we derived psychological factors based on the Theory of Planned Behaviour, estimated them based on structural equation modelling, and included them...

  9. 77 FR 24381 - Security Zone; Passenger Vessel SAFARI EXPLORER Arrival/Departure, Kaunakakai Harbor, Molokai, HI

    Science.gov (United States)

    2012-04-24

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA87 Security Zone; Passenger Vessel SAFARI EXPLORER Arrival/ Departure, Kaunakakai Harbor, Molokai, HI AGENCY: Coast Guard, DHS. ACTION: Temporary interim...

  10. 78 FR 70494 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Science.gov (United States)

    2013-11-26

    ... 14 CFR Part 97 [Docket No. 30929; Amdt. No. 3564] Standard Instrument Approach Procedures, and... Standard Instrument Approach Procedures (SIAPs) and associated Takeoff Minimums and Obstacle Departure... from: 1. FAA Public Inquiry Center (APA-200), FAA Headquarters Building, 800 Independence Avenue...

  11. Testing for departures from additivity in mixtures of perfluoroalkyl acids (PFAAs)

    Science.gov (United States)

    This study is a follow-up to a paper by Carr, et al. that determined a design structure to optimally test for departures from additivity in a fixed ratio mixture of four perfluoroalkyl acids (PFAAs) using an in vitro transiently-transfected COS- 1 PPARa reporter model with an NHA...

  12. Developing Intercultural Understanding for Study Abroad: Students' and Teachers' Perspectives on Pre-Departure Intercultural Learning

    Science.gov (United States)

    Holmes, P.; Bavieri, L.; Ganassin, S.

    2015-01-01

    This study reports on students' and teachers' perspectives on a programme designed to develop Erasmus students' intercultural understanding prior to going abroad. We aimed to understand how students and their teachers perceived pre-departure materials in promoting their awareness of key concepts related to interculturality (e.g., essentialism,…

  13. Impacts of cloud flare-ups on hurricane intensity resulting from departures from balance laws

    Directory of Open Access Journals (Sweden)

    T. N. Krishnamurti

    2012-05-01

    Full Text Available Cloud flare-ups along the inner eye wall of a hurricane lead to enhancement of cloud scale divergence, which in turn leads to a large local enhancement of the departure from balance laws and can lead to local supergradient winds. This scenario is tested using the results from a mesoscale microphysical model at horizontal resolution of 1.33 km for the simulation of hurricane Katrina. Rainwater mixing ratio tags growing cloud elements. The departure from balance laws includes terms such as the local, horizontal and vertical advections of divergence, divergence square and a term invoking the gradient of vertical velocity. It is noted that these terms collectively contribute to a substantial local enhancement of the departure from balance laws. Departures from balance laws are related to the radial gradient wind imbalances in a storm-centred coordinate. In this study, several examples, from the hurricane Katrina simulations, that display this scenario of rapid intensification are illustrated. Organisation of convection in the azimuthal direction seems important for the hurricane scale; cloud flare-ups away from such regions of azimuthal organisation fail to contribute to this scenario for the overall intensification of the hurricane.

  14. Real Time Metrics and Analysis of Integrated Arrival, Departure, and Surface Operations

    Science.gov (United States)

    Sharma, Shivanjli; Fergus, John

    2017-01-01

    A real time dashboard was developed in order to inform and present users notifications and integrated information regarding airport surface operations. The dashboard is a supplement to capabilities and tools that incorporate arrival, departure, and surface air-traffic operations concepts in a NextGen environment. As trajectory-based departure scheduling and collaborative decision making tools are introduced in order to reduce delays and uncertainties in taxi and climb operations across the National Airspace System, users across a number of roles benefit from a real time system that enables common situational awareness. In addition to shared situational awareness the dashboard offers the ability to compute real time metrics and analysis to inform users about capacity, predictability, and efficiency of the system as a whole. This paper describes the architecture of the real time dashboard as well as an initial set of metrics computed on operational data. The potential impact of the real time dashboard is studied at the site identified for initial deployment and demonstration in 2017; Charlotte-Douglas International Airport. Analysis and metrics computed in real time illustrate the opportunity to provide common situational awareness and inform users of metrics across delay, throughput, taxi time, and airport capacity. In addition, common awareness of delays and the impact of takeoff and departure restrictions stemming from traffic flow management initiatives are explored. The potential of the real time tool to inform the predictability and efficiency of using a trajectory-based departure scheduling system is also discussed.

  15. The effect of perceived mobility necessity in the choice of departure time

    DEFF Research Database (Denmark)

    Thorhauge, Mikkel; Cherchi, Elisabetta; Rich, Jeppe

    2014-01-01

    Departure time choice plays a crucial role in addressing the problem of urban congestion. Since the work of Small (1982), many studies have shown that travelers trade-off between travel time and scheduling delay and that travel time variability also plays an important role because uncertainty is ...

  16. Boosting Lyα and He II λ1640 Line Fluxes from Population III Galaxies: Stochastic IMF Sampling and Departures from Case-B

    Science.gov (United States)

    Mas-Ribas, Lluís; Dijkstra, Mark; Forero-Romero, Jaime E.

    2016-12-01

    We revisit calculations of nebular hydrogen Lyα and He ii λ1640 line strengths for Population III (Pop III) galaxies, undergoing continuous, and bursts of, star formation. We focus on initial mass functions (IMFs) motivated by recent theoretical studies, which generally span a lower range of stellar masses than earlier works. We also account for case-B departures and the stochastic sampling of the IMF. In agreement with previous work, we find that departures from case-B can enhance the Lyα flux by a factor of a few, but we argue that this enhancement is driven mainly by collisional excitation and ionization, and not due to photoionization from the n = 2 state of atomic hydrogen. The increased sensitivity of the Lyα flux to the high-energy end of the galaxy spectrum makes it more subject to stochastic sampling of the IMF. The latter introduces a dispersion in the predicted nebular line fluxes around the deterministic value by as much as a factor of ∼4. In contrast, the stochastic sampling of the IMF has less impact on the emerging Lyman Werner photon flux. When case-B departures and stochasticity effects are combined, nebular line emission from Pop III galaxies can be up to one order of magnitude brighter than predicted by “standard” calculations that do not include these effects. This enhances the prospects for detection with future facilities such as the James Webb Space Telescope and large, ground-based telescopes.

  17. 76 FR 13204 - Agency Information Collection Activities: Request for Entry or Departure for Flights to and From...

    Science.gov (United States)

    2011-03-10

    ... Departure for Flights to and From Cuba AGENCY: U.S. Customs and Border Protection (CBP), Department of... requirement concerning the Request for Entry or Departure for Flights to and from Cuba. This request for... respondents or record keepers from the collection of information (a total capital/startup costs and operations...

  18. Comparative evaluation of visual outcomes and corneal asphericity after laser-assisted in situ keratomileusis with the six-dimension Amaris excimer laser system

    Science.gov (United States)

    Piao, JunJie; Li, Ying-Jun; Whang, Woong-Joo; Choi, Mihyun; Kang, Min Ji; Lee, Jee Hye; Yoon, Geunyoung; Joo, Choun-Ki

    2017-01-01

    Purpose To compare the visual and refractive outcomes after laser-assisted in situ keratomileusis (LASIK) surgery for correction of myopia or myopic astigmatism using a six-dimensional Amaris excimer laser. Methods In this retrospective cohort study, we enrolled 47 eyes of 28 patients (age: 19–36 years) with myopia or myopic astigmatism. We used the Custom Ablation Manager protocol and performed ablations with the SCHWIND AMARIS system. LASIK flaps were cut with an iFS Advanced Femtosecond Laser. Mean static (SCC) and dynamic cyclotorsion (DCC) were evaluated. Visual and refractive outcomes were evaluated during 6 months’ follow-up. Corneal asphericity (Q-value) was analyzed at 4 months postoperatively. Results The spherical equivalent (SE) reduction was statistically significant reduce 1 day after refractive surgery (P Free mode (AF) and 90% in the Corneal Wavefront mode (CW). SCC measurements were within ± 5 degrees in 57% (AF) and 68% (CW) of eyes. Mean DCC was within ± 1 degree in 96% (AF) or 95% (CW) of cases. At 6 months, the uncorrected distance visual acuity was 20/25 or better in all eyes. At last follow-up, both steep and flat keratometry values had significantly flattened in both groups (P < 0.001). Corneal asphericity also increased significantly during the postoperative period for an 8-mm corneal diameter (P < 0.001). Conclusions LASIK for myopia or myopic compound astigmatism correction using the six-dimensional AMARIS 750S excimer laser is safe, effective, and predictable. Postoperative corneal asphericity can be analyzed by linear regression to predict the changes in postoperative corneal asphericity with this approach. PMID:28187180

  19. Bounds for departure from normality and the Frobenius norm of matrix eigenvalues

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.L.

    1994-12-01

    New lower and upper bounds for the departure from normality and the Frobenius norm of the eigenvalues of a matrix axe given. The significant properties of these bounds axe also described. For example, the upper bound for matrix eigenvalues improves upon the one derived by Kress, de Vries and Wegmann in [Lin. Alg. Appl., 8 (1974), pp. 109-120]. The upper bound for departure from normality is sharp for any matrix whose eigenvalues are collinear in the complex plane. Moreover, the latter formula is a practical estimate that costs (at most) 2m multiplications, where m is the number of nonzeros in the matrix. In terms of applications, the results can be used to bound from above the sensitivity of eigenvalues to matrix perturbations or bound from below the condition number of the eigenbasis of a matrix.

  20. Scaling relation between earthquake magnitude and the departure time from P wave similar growth

    Science.gov (United States)

    Noda, Shunta; Ellsworth, William L.

    2016-01-01

    We introduce a new scaling relation between earthquake magnitude (M) and a characteristic of initial P wave displacement. By examining Japanese K-NET data averaged in bins partitioned by Mw and hypocentral distance, we demonstrate that the P wave displacement briefly displays similar growth at the onset of rupture and that the departure time (Tdp), which is defined as the time of departure from similarity of the absolute displacement after applying a band-pass filter, correlates with the final M in a range of 4.5 ≤ Mw ≤ 7. The scaling relation between Mw and Tdp implies that useful information on the final M can be derived while the event is still in progress because Tdp occurs before the completion of rupture. We conclude that the scaling relation is important not only for earthquake early warning but also for the source physics of earthquakes.

  1. Understanding patch departure rules for large carnivores: lion movements support a patch-disturbance hypothesis.

    Science.gov (United States)

    Valeix, Marion; Chamaillé-Jammes, Simon; Loveridge, Andrew J; Davidson, Zeke; Hunt, Jane E; Madzikanda, Hillary; Macdonald, David W

    2011-08-01

    We test two hypotheses that could account for patch departure by large mammalian carnivores. One hypothesis is the unsuccessful-hunt hypothesis, where carnivores leave an area after an unsuccessful hunt but continue hunting in the same area after a successful hunt. The second hypothesis is the patch-disturbance hypothesis, where carnivores depart the area after a successful hunt because of behavioral responses of prey to predator presence. We used global positioning system collars to monitor the movements of African lions (Panthera leo) and identified their kill sites to distinguish between these two hypotheses. Lions moved to a different area (≥ 5 km away) after 87% of the kills, which supports the patch-disturbance hypothesis for patch-departure behavior of large mammalian carnivores.

  2. An Approach to Optimize the Departure Times of Transit Vehicles with Strict Capacity Constraints

    Directory of Open Access Journals (Sweden)

    Huimin Niu

    2013-01-01

    Full Text Available This paper focuses on an urban transit line which connects several residential areas and a workplace during the morning rush hours. The congestion is represented by some passengers who must wait for an extended duration and board the next or the third departure vehicles. This paper divides the time horizon equally into several small periods to measure the dynamic passenger demands. Under period-dependent demand conditions, a biobjective optimization model is developed to determine the departure times of transit vehicles at the start station with strict capacity constraints, in which a heuristic algorithm based on intelligent search and local improvement is designed to solve the model. The developed model can address the case in which more than two passengers arrive at a station simultaneously during one same period and calculate the number of boarded passengers. Finally, the model and algorithm have been successfully verified by a numerical example.

  3. 41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?

    Science.gov (United States)

    2010-07-01

    ... departure/arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and... dates and times on my travel claim? You must record the date of departure from, and arrival at, the... visited. You do not have to record departure/arrival times, but you must annotate your travel claim when...

  4. AirSea Battle: A Point-of-Departure Operational Concept

    Science.gov (United States)

    2010-01-01

    advanced foreign ASCMs available on the market. See http://www.navy.mil/navydata/ fact_display.asp? cid =2200&tid= 200&ct=2. The US Navy had 250 nm...No. 2 (Spring 2008), pp. 79–95. AirSea Battle: A Point-of-Departure operational Concept 77 interception operations ( MIO ) against ships bound for...priority taskings, and thus would not generally be available to support MIO operations. However, Air Force bombers with their large payloads and long

  5. Lane Departure System Design using with IR Camera for Night-time Road Conditions

    Directory of Open Access Journals (Sweden)

    Osman Onur Akırmak

    2015-02-01

    Full Text Available Today, one of the largest areas of research and development in the automobile industry is road safety. Many deaths and injuries occur every year on public roads from accidents caused by sleepy drivers, that technology could have been used to prevent. Lane detection at night-time is an important issue in driving assistance systems. This paper deals with vision-based lane detection and tracking at night-time. This project consists of a research and development of an algorithm for automotive systems to detect the departure of vehicle from out of lane. Once the situation is detected, a warning is issued to the driver with sound and visual message through “Head Up Display” (HUD system. The lane departure is detected through the images obtained from a single IR camera, which identifies the departure at a satisfactory accuracy via improved quality of video stream. Our experimental results and accuracy evaluation show that our algorithm has good precision and our detecting method is suitable for night-time road conditions.

  6. Individual variation affects departure rate from the natal pond in an ephemeral pond-breeding anuran

    Science.gov (United States)

    Chelgren, N.D.; Rosenberg, D.K.; Heppell, S.S.; Gitelman, A.I.

    2008-01-01

    Frogs exhibit extreme plasticity and individual variation in growth and behavior during metamorphosis, driven by interactions of intrinsic state factors and extrinsic environmental factors. In northern red-legged frogs (Rana aurora Baird and Girard, 1852), we studied the timing of departure from the natal pond as it relates to date and size of individuals at metamorphosis in the context of environmental uncertainty. To affect body size at metamorphosis, we manipulated food availability during the larval stage for a sample (317) of 1045 uniquely marked individuals and released them at their natal ponds as newly metamorphosed frogs. We recaptured 34% of marked frogs in pitfall traps as they departed and related the timing of their initial terrestrial movements to individual properties using a time-to-event model. Median age at first capture was 4 and 9 days postmetamorphosis at two sites. The rate of departure was positively related to body size and to date of metamorphosis. Departure rate was strongly negatively related to time elapsed since rainfall, and this effect was diminished for smaller and later metamorphosing frogs. Individual variation in metamorphic traits thus affects individuals' responses to environmental variability, supporting a behavioral link with variation in survival associated with these same metamorphic traits. ?? 2008 NRC.

  7. 78 FR 70570 - Agency Information Collection Activities: Arrival and Departure Record (Forms I-94 and I-94W) and...

    Science.gov (United States)

    2013-11-26

    .... There are no proposed changes to Form I-94. Type of Review: Revision. Affected Public: Individuals, Carriers, and the Travel and Tourism Industry. Form I-94 (Arrival and Departure Record) Estimated Number...

  8. 76 FR 28239 - Agency Information Collection Activities: Arrival and Departure Record (Forms I-94 and I-94W) and...

    Science.gov (United States)

    2011-05-16

    ... proposed changes to CBP Form I-94. Type of Review: Revision. Affected Public: Individuals, Carriers, and the Travel and Tourism Industry. I-94 (Arrival and Departure Record) Estimated Number of...

  9. Study on the influence of the rotational speed of polishing disk on material removal in aspheric surface compliant polishing

    Directory of Open Access Journals (Sweden)

    Liyong Hu

    2015-03-01

    Full Text Available When a soft polishing tool is compressed on a stiff workpiece of curved surface, the contact area is a piece of the curved surface. In the process of aspheric surface polishing, the machining speed is always provided by the rotational speed of the spindle of a computer numerical control lathe. Yet, the polishing tool is usually made rotating to remove cutting scraps and broken abrasives from the contact area. The rotational speed of the polishing tool would change the distribution state of the relative speed in the whole contact area, and it would definitely change the volume of material removal in the surface of the workpiece. This article studies how the rotational speed of the polishing tool changes the distribution state of the relative speed in the whole contact area and material removal in the volume of the surface of the workpiece. The computing results show that the volume of material removal increases with the increase in both the rotational speed of polishing disk and the rotational speed of lathe spindle, but the polishing quality is totally not in this case.

  10. Effect of aspheric multifocal toric IOL implantation on visual acuity and contrast sensitivity in patients with cataract

    Directory of Open Access Journals (Sweden)

    Ling-Ling Zhang

    2016-07-01

    Full Text Available AIM: To observe the effect of intraocular lens(IOLimplantation on visual acuity and contrast sensitivity in patients with cataract.METHODS: Fifty-eight cases(72 eyescataract patients with regular cornel astigmatism, in our hospital from May 2014 to May 2015 were randomly divided into two groups to undergo phacoemulsification and IOL implantation: the observation group: 29 cases(36 eyesreceived multifocal toric IOL implantation; the control group: 29 cases(36 eyesreceived monofocal toric IOL implantation. Uncorrected distance visual acuity(UCDVA, uncorrected near visual acuity(UCNVA, best corrected distance visual acuity(BCDVA, the best corrected near visual acuity(BCNVA, total eye astigmatism, and the dark contrast sensitivity were observed for these patients at 1 and 6mo after cataract surgery. RESULTS: There were no statistical significant difference between the two groups at postoperative 1, 6mo on UCDVA, BCNVA, BCDVA and total eye astigmatism(P>0.05. UCNVA of observation group at 1 and 6mo were better than those of control group(PPCONCLUSION: Both monofocal toric IOL implantation, and aspheric multifocal toric IOL implantation for cataract with regular corneal astigmatism are effective to improve visual acuity. But the latter treatment would contribute to the improvement of uncorrected near visual acuity and the dark contrast sensitivity.

  11. Comprehensive Evaluation of Anterior Corneal Change in Asphericity Calculated by the Tangential Radius of Curvature after LASIK

    Science.gov (United States)

    Ying, Jinglu; Cai, Jianqiu; Zhu, Leru

    2017-01-01

    To evaluate the change in the anterior corneal asphericity (ΔQ) comprehensively calculated using the tangential radius (rt) after LASIK. Forty-two right eyes were evaluated using the Orbscan II corneal topographer. The pre- and postoperative Q-values of the flat principal semimeridians calculated by the sagittal radius were compared to those by the tangential radius. The Q-value of each semimeridian in the horizontal region was calculated by rt. Fourier fitting was used to model the 360-semimeridional variation of Q-values and to fit the Q-values in the vertical region before and after surgery. There were significant differences in Q-values between the two methods before (P < 0.001) and after surgery (P = 0.003). A significant increase in postoperative Q-value was detected compared to preoperative Q-value (P < 0.001) calculated by rt. The 360-semimeridional variation of the Q-values was well fitted with a third- and fourth-degree Fourier function before and after surgery. The ΔQ-value distribution presented double valley variation, with the amount of ΔQ being lowest in the near-vertical regions and highest in the near-horizontal regions. Calculating the Q-value with rt combined with Fourier fitting, we evaluated 360 ΔQ-values' variation of semimeridians of the entire anterior corneal surface and then displayed true and complete anterior corneal shape after LASIK.

  12. Direct design of aspherical lenses for extended non-Lambertian sources in three-dimensional rotational geometry.

    Science.gov (United States)

    Wu, Rengmao; Hua, Hong

    2016-01-25

    Illumination design used to redistribute the spatial energy distribution of light source is a key technique in lighting applications. However, there is still no effective illumination design method for extended sources, especially for extended non-Lambertian sources. What we present here is to our knowledge the first direct method for extended non-Lambertian sources in three-dimensional (3D) rotational geometry. In this method, both meridional rays and skew rays of the extended source are taken into account to tailor the lens profile in the meridional plane. A set of edge rays and interior rays emitted from the extended source which will take a given direction after the refraction of the aspherical lens are found by the Snell's law, and the output intensity at this direction is then calculated to be the integral of the luminance function of the outgoing rays at this direction. This direct method is effective for both extended non-Lambertian sources and extended Lambertian sources in 3D rotational symmetry, and can directly find a solution to the prescribed design problem without cumbersome iterative illuminance compensation. Two examples are presented to demonstrate the effectiveness of the proposed method in terms of performance and capacity for tackling complex designs.

  13. 22 CFR 46.6 - Departure from the Canal Zone, the Trust Territory of the Pacific Islands, or outlying...

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Departure from the Canal Zone, the Trust Territory of the Pacific Islands, or outlying possessions of the United States. 46.6 Section 46.6 Foreign Relations DEPARTMENT OF STATE VISAS CONTROL OF ALIENS DEPARTING FROM THE UNITED STATES § 46.6 Departure from the Canal Zone, the Trust Territory...

  14. Increased evidence for the prognostic value of primary tumor asphericity in pretherapeutic FDG PET for risk stratification in patients with head and neck cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hofheinz, Frank; Lougovski, Alexandr [Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, PET Center, Dresden (Germany); Zoephel, Klaus; Hentschel, Maria [University Hospital Carl Gustav Carus, Technische Universitaet Dresden, Department of Nuclear Medicine, Dresden (Germany); Steffen, Ingo G.; Wedel, Florian; Buchert, Ralph; Brenner, Winfried [Charite - Universitaetsmedizin Berlin, Department of Nuclear Medicine, Berlin (Germany); Apostolova, Ivayla [Universitaetsklinikum Magdeburg A.oe.R., Klinik fuer Radiologie und Nuklearmedizin, Magdeburg (Germany); Baumann, Michael [University Hospital Carl Gustav Carus, Technische Universitaet Dresden, Department of Radiation Oncology, Dresden (Germany); OncoRay - National Center for Radiation Research in Oncology, Dresden (Germany); Institute of Radiooncology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Kotzerke, Joerg; Hoff, Joerg van den [Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, PET Center, Dresden (Germany); University Hospital Carl Gustav Carus, Technische Universitaet Dresden, Department of Nuclear Medicine, Dresden (Germany)

    2014-11-22

    In a previous study, we demonstrated the first evidence that the asphericity (ASP) of pretherapeutic FDG uptake in the primary tumor provides independent prognostic information in patients with head and neck cancer. The aim of this work was to confirm these results in an independent patient group examined at a different site. FDG-PET/CT was performed in 37 patients. The primary tumor was delineated by an automatic algorithm based on adaptive thresholding. For the resulting ROIs, the metabolically active part of the tumor (MTV), SUV{sub max}, SUV{sub mean}, total lesion glycolysis (TLG) and ASP were computed. Univariate Cox regression with respect to progression free survival (PFS) and overall survival (OS) was performed. For survival analysis, patients were divided in groups of high and low risk according to the parameter cut-offs defined in our previous work. In a second step, the cut-offs were adjusted to the present data. Univariate and multivariate Cox regression was performed for the pooled data consisting of the current and the previously described patient group (N = 68). In multivariate Cox regression, clinically relevant parameters were included. Univariate Cox regression using the previously published cut-off values revealed TLG (hazard ratio (HR) = 3) and ASP (HR = 3) as significant predictors for PFS. For OS MTV (HR = 2.7) and ASP (HR = 5.9) were significant predictors. Using the adjusted cutoffs MTV (HR = 2.9/3.3), TLG (HR = 3.1/3.3) and ASP (HR = 3.1/5.9) were prognostic for PFS/OS. In the pooled data, multivariate Cox regression revealed a significant prognostic value with respect to PFS/OS for MTV (HR = 2.3/2.1), SUV{sub max} (HR = 2.1/2.5), TLG (HR = 3.5/3.6), and ASP (HR = 3.4/4.4). Our results confirm the independent prognostic value of ASP of the pretherapeutic FDG uptake in the primary tumor in patients with head and neck cancer. Moreover, these results demonstrate that ASP can be determined unambiguously across different sites. (orig.)

  15. Visual acuity and patient satisfaction at varied distances and lighting conditions after implantation of an aspheric diffractive multifocal one-piece intraocular lens

    Directory of Open Access Journals (Sweden)

    Chang DH

    2016-08-01

    Full Text Available Daniel H Chang Empire Eye and Laser Center, Bakersfield, CA, USA Purpose: The aim of the study is to evaluate the visual acuity and patient satisfaction at varied distances under photopic and mesopic lighting conditions in patients bilaterally implanted with aspheric diffractive multifocal one-piece intraocular lenses. Methods: In this retrospective–prospective study, 16 patients with a mean age of 66.2±9.2 years (range: 50–81 years who had undergone bilateral phacoemulsification surgery with implantation of a Tecnis multifocal one-piece intraocular lens (ZMB00 were evaluated. Monocular and binocular uncorrected and distance-corrected visual acuities were measured at distance (20 ft, intermediate (70–80 cm, and near (35–40 cm under photopic (85 cd/m2 and mesopic (3 cd/m2 lighting conditions and were compared using the paired t-test. All patients also completed a subjective questionnaire. Results: At a mean follow-up of 9.5±3.9 months, distance, near, and intermediate visual acuity improved significantly from preoperative acuity. Under photopic and mesopic conditions, 93.8% and 62.5% of patients, respectively, had binocular uncorrected intermediate visual acuity of 20/40 or better, and 62.5% and 31.3% of patients had binocular uncorrected near visual acuity of 20/20 or better. All patients were satisfied with their overall vision without using glasses and/or contact lenses when compared with before surgery. A total of 87.5% of patients reported no glare and 68.8% of patients reported no halos around lights at night. Conclusion: Tecnis multifocal one-piece intraocular lenses provide good distance, intermediate, and near visual acuity under photopic as well as mesopic lighting conditions. High levels of spectacle independence with low levels of photic phenomenon were achieved, resulting in excellent patient satisfaction. Keywords: Tecnis multifocal one-piece IOL, photopic visual acuity, mesopic visual acuity, intermediate visual

  16. Precise and accurate train run data: Approximation of actual arrival and departure times

    DEFF Research Database (Denmark)

    Richter, Troels; Landex, Alex; Andersen, Jonas Lohmann Elkjær

    trains have come to a halt nor when trains have set in motion again. Thus the measurements are inaccurate and do not express the experience of the passengers. A commonly accepted method to make this measurement possible is to construct a correction function to the track circuit based measurement....... This function estimates the inaccuracy or bias of the measurement and thus which offset is needed to approximate the actual arrival and departure times. The development of such a function is described in this paper. The development is based on international best practices combined with what is technically...

  17. Reducing Fuel Consumption in Bucharest Terminal Area for Flights Using a Standard Instrument Departure

    Directory of Open Access Journals (Sweden)

    Alin George DIACONU

    2011-01-01

    Full Text Available Reconfiguration of the standard instrument departure and standard arrival routes at certain airports can bring significant reductions in fuel consumption and level of noise. This can be done either by implementing modern radionavigation aids for terminal areas or by eliminating the flying restrictions over cities and inhabited places and designing of low level of noise procedures for these areas. These solutions have other important benefits like decreasing the workload for the air traffic controllers and reducing the total flight time. The paper describes an operational solution in this manner for Bucharest Henri Coanda International Airport.

  18. Functional Analysis for an Integrated Capability of Arrival/Departure/Surface Management with Tactical Runway Management

    Science.gov (United States)

    Phojanamongkolkij, Nipa; Okuniek, Nikolai; Lohr, Gary W.; Schaper, Meilin; Christoffels, Lothar; Latorella, Kara A.

    2014-01-01

    The runway is a critical resource of any air transport system. It is used for arrivals, departures, and for taxiing aircraft and is universally acknowledged as a constraining factor to capacity for both surface and airspace operations. It follows that investigation of the effective use of runways, both in terms of selection and assignment as well as the timing and sequencing of the traffic is paramount to the efficient traffic flows. Both the German Aerospace Center (DLR) and NASA have developed concepts and tools to improve atomic aspects of coordinated arrival/departure/surface management operations and runway configuration management. In December 2012, NASA entered into a Collaborative Agreement with DLR. Four collaborative work areas were identified, one of which is called "Runway Management." As part of collaborative research in the "Runway Management" area, which is conducted with the DLR Institute of Flight Guidance, located in Braunschweig, the goal is to develop an integrated system comprised of the three DLR tools - arrival, departure, and surface management (collectively referred to as A/D/S-MAN) - and NASA's tactical runway configuration management (TRCM) tool. To achieve this goal, it is critical to prepare a concept of operations (ConOps) detailing how the NASA runway management and DLR arrival, departure, and surface management tools will function together to the benefit of each. To assist with the preparation of the ConOps, the integrated NASA and DLR tools are assessed through a functional analysis method described in this report. The report first provides the highlevel operational environments for air traffic management (ATM) in Germany and in the U.S., and the descriptions of the DLR's A/D/S-MAN and NASA's TRCM tools at the level of details necessary to compliment the purpose of the study. Functional analyses of each tool and a completed functional analysis of an integrated system design are presented next in the report. Future efforts to fully

  19. Evaluation of actual retinal images produced by misaligned aspheric intraocular lenses in a model eye

    Directory of Open Access Journals (Sweden)

    Fujikado T

    2014-11-01

    Full Text Available Takashi Fujikado,1 Makoto Saika2 1Department of Applied Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan; 2Research and Development Department of Topcon Corporation, Tokyo, Japan Purpose: To examine the effect of misalignment (decentration and tilt of intraocular lenses (IOLs on retinal image quality using a water-immersed model eye with corneal spherical aberration adjusted to the values found in normal human eyes (spherical aberration 0.25 µm; pupil diameter 6 mm.Methods: Three types of IOL holders were prepared. The first was without decentration or tilt, the second had a decentration of 0.5 mm, and the third had a tilt of 5.0°. One spherical IOL and three aspherical IOLs, each with a power of +20 D, were set in the holders and their optical properties (wave front aberration, defocused modulation transfer function, defocused point spread function, and Landolt ring simulations were compared.Results: Coma aberrations generated by misaligned IOLs were related to the spherical aberration corrective power of the IOLs. Landolt ring simulations show that the depth of focus increased as spherical aberration increased and that the retinal image quality was degraded by increases in coma aberration.Conclusion: Coma aberration was generated by IOLs with a large degree of spherical aberration correction, leading to reduced retinal image quality when the IOL was misaligned. This suggests that, in a clinical setting, the quality of vision might be improved by reducing the degree of coma aberration using IOLs that retain, or minimally correct, spherical aberration. Keywords: coma aberration, decentration, misalignment, spherical aberration, tilt

  20. Two Distinct-absorption X-Ray Components from Type IIn Supernovae: Evidence for Asphericity in the Circumstellar Medium

    Science.gov (United States)

    Katsuda, Satoru; Maeda, Keiichi; Bamba, Aya; Terada, Yukikatsu; Fukazawa, Yasushi; Kawabata, Koji; Ohno, Masanori; Sugawara, Yasuharu; Tsuboi, Yohko; Immler, Stefan

    2016-12-01

    We present multi-epoch X-ray spectral observations of three Type IIn supernovae (SNe), SN 2005kd, SN 2006jd, and SN 2010jl, acquired with Chandra, XMM-Newton, Suzaku, and Swift. Previous extensive X-ray studies of SN 2010jl have revealed that X-ray spectra are dominated by thermal emission, which likely arises from a hot plasma heated by a forward shock propagating into a massive circumstellar medium (CSM). Interestingly, an additional soft X-ray component was required to reproduce the spectra at a period of ˜1-2 years after the SN explosion. Although this component is likely associated with the SN, its origin remained an open question. We find a similar, additional soft X-ray component from the other two SNe IIn as well. Given this finding, we present a new interpretation for the origin of this component; it is thermal emission from a forward shock essentially identical to the hard X-ray component, but directly reaches us from a void of the dense CSM. Namely, the hard and soft components are responsible for the heavily and moderately absorbed components, respectively. The co-existence of the two components with distinct absorptions as well as the delayed emergence of the moderately absorbed X-ray component could be evidence for asphericity of the CSM. We show that the X-ray spectral evolution can be qualitatively explained by considering a torus-like geometry for the dense CSM. Based on our X-ray spectral analyses, we estimate the radius of the torus-like CSM to be on the order of ˜5 × 1016 cm.

  1. Measurement of focusing properties for high numerical aperture optics using an automated submicron beamprofiler

    CERN Document Server

    Chapman, J J; Streed, E W; Kielpinski, D

    2007-01-01

    The focusing properties of three aspheric lenses with numerical aperture (NA) between 0.53 and 0.68 were directly measured using an interferometrically referenced scanning knife-edge beam profiler with sub-micron resolution. The results obtained for two of the three lenses tested were in agreement with paraxial gaussian beam theory. It was also found that the highest NA aspheric lens which was designed for 830nm was not diffraction limited at 633nm. This process was automated using motorized translation stages and provides a direct method for testing the design specifications of high numerical aperture optics.

  2. Study on Lightweight and Optimization of Supporting Structure for the Rectangular Aspherical Reflector%长条型非球面反射镜轻量化及支撑结构优化研究

    Institute of Scientific and Technical Information of China (English)

    宋朝辉; 卢锷; 吴清文

    2001-01-01

    Lightweight, high resolution, visible light space remoter with wide view f ield has been developed with miniaturization of satellite. First lightweight t e chnical approaches are applied for The rectangular aspherical reflector used in lightweight remoter, then the static analysis of its supporting structure was ma de by means of FEM(Finite Element Method). The mirror is improved & its structure is selected to meet the WFE specification.%针对轻型光学空间遥感器的长条型非球面反射镜,首先进行了轻量化研究,然后针 对 支撑结构的初步设计方案,采用有限元法进行了静力学分析和计算。以对镜面面型精度的影 响为评价指标,进行了有效的多次迭代优化,最终确定了满足要求的支撑结构方案。

  3. Bubble Departure from Metal-Graphite Composite Surfaces and Its Effects on Pool Boiling Heat Transfer

    Science.gov (United States)

    Chao, David F.; Sankovic, John M.; Motil, Brian J.; Yang, W-J.; Zhang, Nengli

    2010-01-01

    The formation and growth processes of a bubble in the vicinity of graphite micro-fiber tips on metal-graphite composite boiling surfaces and their effects on boiling behavior are investigated. It is discovered that a large number of micro bubbles are formed first at the micro scratches and cavities on the metal matrix in pool boiling. By virtue of the non-wetting property of graphite, once the growing micro bubbles touch the graphite tips, the micro bubbles are sucked by the tips and merged into larger micro bubbles sitting on the end of the tips. The micro bubbles grow rapidly and coalesce to form macro bubbles, each spanning several tips. The necking process of a detaching macro bubble is analyzed. It is revealed that a liquid jet is produced by sudden break-off of the bubble throat. The composite surfaces not only have higher temperatures in micro- and macrolayers but also make higher frequency of the bubble departure, which increase the average heat fluxes in both the bubble growth stage and in the bubble departure period. Based on these analyses, the enhancement mechanism of pool boiling heat transfer on composite surfaces is clearly revealed.

  4. A new shared control for lane keeping and road departure prevention

    Science.gov (United States)

    Merah, Abdelkader; Hartani, Kada; Draou, Azeddine

    2016-01-01

    In recent years, the driver's active assistances have become important features in commercialised vehicles. In this paper, we present one of these features which consists of an advanced driver assistance system for lane keeping. A thorough analysis of its performance and stability with respect to variations in driver behaviour will be given. Firstly, the lateral control model based on visual preview is established and the kinematics model based on visual preview, including speed and other factors, is used to calculate the lateral error and direction error. Secondly, and according to the characteristics of the lateral control, an efficient strategy of intelligent electric vehicle lateral mode is proposed. The integration of the vehicle current lateral error and direction error is chosen as the parameter of the sliding mode switching function to design the sliding surface. The control variables are adjusted according to the fuzzy control rules to ensure that they meet the existence and reaching condition. A new fuzzy logic-based switching strategy with an efficient control law is also proposed to ensure a level of continuous and variable sharing according to the state of the driver and the vehicle positioning on the roadway. The proposed control law acts either at the centre of the lane, as a lane keeping assistance system to reduce the driver's workload for long trips, or as a lane departure avoidance system that intervenes for unintended lane departures. Simulation results are included in this paper to explain this concept.

  5. Research on Arrival/Departure Scheduling of Flights on Multirunways Based on Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Hang Zhou

    2014-01-01

    Full Text Available Aiming at the phenomenon of a large number of flight delays in the terminal area makes a reasonable scheduling for the approach and departure flights, which will minimize flight delay losses and improve runway utilization. This paper considered factors such as operating conditions and safety interval of multi runways; the maximum throughput and minimum flight delay losses as well as robustness were taken as objective functions; the model of optimization scheduling of approach and departure flights was established. Finally, the genetic algorithm was introduced to solve the model. The results showed that, in the program whose advance is not counted as a loss, its runway throughput is improved by 18.4%, the delay losses are reduced by 85.8%, and the robustness is increased by 20% compared with the results of FCFS (first come first served algorithm, while, compared with the program whose advance is counted as a loss, the runway throughput is improved by 15.16%, flight delay losses are decreased by 75.64%, and the robustness is also increased by 20%. The algorithm can improve the efficiency and reduce delay losses effectively and reduce the workload of controllers, thereby improving economic results.

  6. Assessing Impact of Dual Sensor Enhanced Flight Vision Systems on Departure Performance

    Science.gov (United States)

    Kramer, Lynda J.; Etherington, Timothy J.; Severance, Kurt; Bailey, Randall E.

    2016-01-01

    Synthetic Vision (SV) and Enhanced Flight Vision Systems (EFVS) may serve as game-changing technologies to meet the challenges of the Next Generation Air Transportation System and the envisioned Equivalent Visual Operations (EVO) concept - that is, the ability to achieve the safety and operational tempos of current-day Visual Flight Rules operations irrespective of the weather and visibility conditions. One significant obstacle lies in the definition of required equipage on the aircraft and on the airport to enable the EVO concept objective. A motion-base simulator experiment was conducted to evaluate the operational feasibility and pilot workload of conducting departures and approaches on runways without centerline lighting in visibility as low as 300 feet runway visual range (RVR) by use of onboard vision system technologies on a Head-Up Display (HUD) without need or reliance on natural vision. Twelve crews evaluated two methods of combining dual sensor (millimeter wave radar and forward looking infrared) EFVS imagery on pilot-flying and pilot-monitoring HUDs. In addition, the impact of adding SV to the dual sensor EFVS imagery on crew flight performance and workload was assessed. Using EFVS concepts during 300 RVR terminal operations on runways without centerline lighting appears feasible as all EFVS concepts had equivalent (or better) departure performance and landing rollout performance, without any workload penalty, than those flown with a conventional HUD to runways having centerline lighting. Adding SV imagery to EFVS concepts provided situation awareness improvements but no discernible improvements in flight path maintenance.

  7. Investigation, Modeling, and Analysis of Integrated Metroplex Arrival and Departure Coordination Concepts

    Science.gov (United States)

    Clarke, John-Paul B.; Brooks, James; McClain, Evan; Paladhi, Anwesha Roy; Li, Leihong; Schleicher, David; Saraf, Aditya; Timar, Sebastian; Crisp, Don; Bertino, Jason; Laroza, Ryan; Cross, Carolyn

    2012-01-01

    This work involves the development of a concept that enhances integrated metroplex arrival and departure coordination, determines the temporal (the use of time separation for aircraft sharing the same airspace resources) and spatial (the use of different routes or vertical profiles for aircraft streams at any given time) impact of metroplex traffic coordination within the National Airspace System (NAS), and quantifies the benefits of the most desirable metroplex traffic coordination concept. Researching and developing metroplex concepts is addressed in this work that broadly applies across the range of airspace and airport demand characteristics envisioned for NextGen metroplex operations. The objective of this work is to investigate, formulate, develop models, and analyze an operational concept that mitigates issues specific to the metroplex or that takes advantage of unique characteristics of metroplex airports to improve efficiencies. The concept is an innovative approach allowing the NAS to mitigate metroplex interdependencies between airports, optimize metroplex arrival and departure coordination among airports, maximize metroplex airport throughput, minimize delay due to airport runway configuration changes, increase resiliency to disruptions, and increase the tolerance of the system to degrade gracefully under adverse conditions such as weather, traffic management initiatives, and delays in general.

  8. An Analysis of Departure Behaviors of High-Quality Career Designated First-Term Marine Officers

    Science.gov (United States)

    2016-03-01

    forms. The binary variables include race, marital status, gender and education beyond a bachelor’s degree. We simplify the race variable into two...correlation with reduced performance that could be attributed to either increased diversity or gender . During the same time period, there is a...Designated 7 Final Non -acceptance Adapted from: Halton, M. (2015, January 5). Career designation pre-board population identification.[Power Point

  9. Boosting Lya and HeII 1640A Line Fluxes from Pop III Galaxies: Stochastic IMF Sampling and Departures from Case-B

    CERN Document Server

    Mas-Ribas, Lluís; Forero-Romero, Jaime E

    2016-01-01

    We revisit calculations of nebular hydrogen Lya and HeII 1640A line strengths for population III galaxies, undergoing continuous and bursts of star formation. We focus on initial mass functions (IMFs) motivated by recent theoretical studies, which generally span a lower range of stellar masses than earlier works. We also account for case-B departures and the stochastic sampling of the IMF. In agreement with previous works, we find that departures from case-B can enhance the Lya flux by a factor of a few, but we argue that this enhancement is driven mainly by collisional excitation and ionization, and not due to photoionization from the n = 2 state of atomic hydrogen. The increased sensitivity of the Lya flux to the high-energy end of the galaxy spectrum makes it more subject to stochastic sampling of the IMF. The latter introduces a dispersion in the predicted nebular line fluxes around the deterministic value by as much as a factor of ~4. In contrast, the stochastic sampling of the IMF has less impact on the...

  10. Design and high-volume manufacture of low-cost molded IR aspheres for personal thermal imaging devices

    Science.gov (United States)

    Zelazny, A. L.; Walsh, K. F.; Deegan, J. P.; Bundschuh, B.; Patton, E. K.

    2015-05-01

    The demand for infrared optical elements, particularly those made of chalcogenide materials, is rapidly increasing as thermal imaging becomes affordable to the consumer. The use of these materials in conjunction with established lens manufacturing techniques presents unique challenges relative to the cost sensitive nature of this new market. We explore the process from design to manufacture, and discuss the technical challenges involved. Additionally, facets of the development process including manufacturing logistics, packaging, supply chain management, and qualification are discussed.

  11. Plasma Pressure Driven Magnetic Self-Focusing of Aspherical Supernovae and Highly Collimated Gamma-Ray Bursts

    CERN Document Server

    Tsui, K H

    2012-01-01

    During the process of core-collapse of a massive star, the iron core evolves into an inner central core and an outer envelope, generating a cavity in between. The dynamics of this cavity, filled with plasma and magnetic field by the rapidly rotating pulsar (spun-down magnetar) at the center, is believed to be very relevant to account for supernovae and gamma-ray bursts \\citep{uzdensky2007}. The interactions of the pressurized conducting plasma and the magnetic field could generate some spatial distributions of plasma and magnetic field within the cavity. In an effort to better understand the spatial distributions, a set of time-dependent magnetohydrodynamic (MHD) equations is used to model this cavity system. Homologous solutions in Lagrangian representation are obtained to account for the spatial structures. Under this self-similar description, the magnetic flux function is governed by an eigenvalue equation with the eigenvalue being the poloidal plasma $\\beta$, which is the ratio of plasma pressure to poloi...

  12. Real-time lane departure warning system based on principal component analysis of grayscale distribution and risk evaluation model

    Institute of Scientific and Technical Information of China (English)

    张伟伟; 宋晓琳; 张桂香

    2014-01-01

    A technology for unintended lane departure warning was proposed. As crucial information, lane boundaries were detected based on principal component analysis of grayscale distribution in search bars of given number and then each search bar was tracked using Kalman filter between frames. The lane detection performance was evaluated and demonstrated in ways of receiver operating characteristic, dice similarity coefficient and real-time performance. For lane departure detection, a lane departure risk evaluation model based on lasting time and frequency was effectively executed on the ARM-based platform. Experimental results indicate that the algorithm generates satisfactory lane detection results under different traffic and lighting conditions, and the proposed warning mechanism sends effective warning signals, avoiding most false warning.

  13. Aspherical-atom modeling of coordination compounds by single-crystal X-ray diffraction allows the correct metal atom to be identified.

    Science.gov (United States)

    Dittrich, Birger; Wandtke, Claudia M; Meents, Alke; Pröpper, Kevin; Mondal, Kartik Chandra; Samuel, Prinson P; Amin Sk, Nurul; Singh, Amit Pratap; Roesky, Herbert W; Sidhu, Navdeep

    2015-02-02

    Single-crystal X-ray diffraction (XRD) is often considered the gold standard in analytical chemistry, as it allows element identification as well as determination of atom connectivity and the solid-state structure of completely unknown samples. Element assignment is based on the number of electrons of an atom, so that a distinction of neighboring heavier elements in the periodic table by XRD is often difficult. A computationally efficient procedure for aspherical-atom least-squares refinement of conventional diffraction data of organometallic compounds is proposed. The iterative procedure is conceptually similar to Hirshfeld-atom refinement (Acta Crystallogr. Sect. A- 2008, 64, 383-393; IUCrJ. 2014, 1,61-79), but it relies on tabulated invariom scattering factors (Acta Crystallogr. Sect. B- 2013, 69, 91-104) and the Hansen/Coppens multipole model; disordered structures can be handled as well. Five linear-coordinate 3d metal complexes, for which the wrong element is found if standard independent-atom model scattering factors are relied upon, are studied, and it is shown that only aspherical-atom scattering factors allow a reliable assignment. The influence of anomalous dispersion in identifying the correct element is investigated and discussed.

  14. Visualization of droplet departure on a superhydrophobic surface and implications to heat transfer enhancement during dropwise condensation

    Science.gov (United States)

    Dietz, C.; Rykaczewski, K.; Fedorov, A. G.; Joshi, Y.

    2010-07-01

    Droplet departure frequency is investigated using environmental scanning electron microscopy with implications to enhancing the rate of dropwise condensation on superhydrophobic surfaces. Superhydrophobic surfaces, formed by cupric hydroxide nanostructures, allow the condensate to depart from a surface with a tilt angle of 30° from the horizontal. The resulting decrease in drop departure size shifts the drop size distribution to smaller radii, which may enhance the heat transfer rate during dropwise condensation. The heat transfer enhancement is estimated by modifying the Rose and Le Fevre drop distribution function to account for a smaller maximum droplet size on a superhydrophobic surface.

  15. Generalized Measure of Departure from No Three-Factor Interaction Model for 2 x 2 x K Contingency Tables

    Directory of Open Access Journals (Sweden)

    Yohei Ban

    2008-12-01

    Full Text Available For 2 x 2 x K contingency tables, Tomizawa considered a Shannon entropy type measure to represent the degree of departure from a log-linear model of no three-factor interaction (the NOTFI model. This paper proposes a generalization of Tomizawa's measure for 2 x 2 x K tables. The measure proposed is expressed by using Patil-Taillie diversity index or Cressie-Read power-divergence. A special case of the proposed measure includes Tomizawa's measure. The proposed measure would be useful for comparing the degrees of departure from the NOTFI model in several tables.

  16. The Transitional Stripped-Envelope SN 2008ax: Spectral Evolution and Evidence for Large Asphericity

    CERN Document Server

    Chornock, R; Li, W; Marion, G H; Foley, R J; Modjaz, M; Rafelski, M; Becker, G D; de Vries, W H; Garnavich, P; Jorgenson, R A; Lynch, D K; Malec, A L; Moran, E C; Murphy, M T; Rudy, R J; Russell, R W; Silverman, J M; Steele, T N; Stockton, A; Wolfe, A M; Woodward, C E

    2010-01-01

    Supernova (SN) 2008ax in NGC 4490 was discovered within hours after shock breakout, presenting the rare opportunity to study a core-collapse SN beginning with the initial envelope-cooling phase immediately following shock breakout. We present an extensive sequence of optical and near-infrared spectra, as well as three epochs of optical spectropolarimetry. Our initial spectra, taken two days after shock breakout, are dominated by hydrogen Balmer lines at high velocity. However, by maximum light, He I lines dominated the optical and near-infrared spectra, which closely resembled those of normal Type Ib supernovae (SNe Ib) such as SN 1999ex. This spectroscopic transition defines Type IIb supernovae, but the strong similarity of SN 2008ax to normal SNe Ib beginning near maximum light, including an absorption feature near 6270A due to H-alpha at high velocities, suggests that many objects classified as SNe Ib in the literature may have ejected similar amounts of hydrogen as SN 2008ax, roughly a few x 0.01 M_sun. E...

  17. 非球面复眼设计及其制备工艺研究%Design and preparation of aspherical compound eye

    Institute of Scientific and Technical Information of China (English)

    郝永平; 李伦; 于军波

    2016-01-01

    提出了一种制备非球面仿生复眼的方法。昆虫的复眼是由一个个尺寸微小的独立小眼沿曲面小眼阵列的方式分布在头部的两侧,以实现大视角探测。设计曲面基底上阵列非均匀微透镜结构,沿径向排列的各级微透镜的焦距及尺寸均不相同。根据几何光学成像原理,计算各级微透镜的尺寸参数,对构建的模型进行光线追迹,优化各级微透镜的尺寸参数。分析不同制备技术特点,研究材料性能及不同材料间的关系,提出了可简单、快速的制备非球面仿生复眼的方法。该方法中,利用精密五轴数控机床加工非球面复眼模具,然后通过压力灌注方法将非球面复眼结构转移出来,获得所需的非球面仿生复眼。通过仿真及实验结果表明,整个曲面仿生复眼边缘成像质量明显提高,各子眼通道均能够采集清晰亮斑。%A preparation method for aspherical bionic compound eye is proposed.The compound eyes of insects are composed of many tiny independent ommatidia,and these ommatidia along the surface of the array distribute on both sides of the head to achieve large angle viewing.The array of non-uniform substrate surface is designed for micro-lens structure,and the focal lengths and sizes of radial arrayed micro-lenses are all different.According to geometrical op-tics imaging principle,size parameters of all level micro-lenses are computed,and the constructed model is carried out by ray-tracing and the size parameters of all level micro-lenses are optimized.The technical characteristics of different preparation methods are analyzed,and material properties and the relationship between different materials are studied, so a simple and fast preparation method for aspherical bionic compound eye is proposed.In this method,the mold of aspherical compound eyes is manufactured by precise five-axis CNC machine and then the aspheric compound eye structure is transferred

  18. 高斯光束非球面镜整形系统的设计%Design of Aspherics Lenses Shaping System on Gaussian Beam

    Institute of Scientific and Technical Information of China (English)

    冯科; 李劲松

    2013-01-01

    Application value of the Gaussian beam with flat-top shaping and some main shaping methods were introduced. Because of the advantages of aspherics, aspherics shaping method was studied, Fermi Dirac function was chosen as a flat-top beam distribution model, and the relationship between its flat-top distribution and the characteristic parameters was analyzed. By analyzing aspherics shaping principle theoretically, according to the law of conservation of energy and ray tracing function, aspheric surface form expression was deduced. Considering the processing factors, the effects of system parameters on the spherical degree was analyzed. And then, by choosing appropriate parameters, MATLAB software was used to solve numerical solution of mapping relation and surface shape curve and fit to get aspheric coefficient. By using ZEMAX optical software to make system modeling, the output beam of light intensity distribution and propagation characteristic could be gotten through the physical optics propagate-POP simulation. As a result, output beam of the flat-top quality is close to the expected effect, and its error mainly comes from numerical calculation accuracy and edge diffraction.%  首先介绍了高斯光束平顶整形的应用价值及一些主要整形方法,由于非球面镜整形的优点,本文研究非球面镜整形法。选择费米-狄拉克函数作为平顶光束模型,并分析了其平顶分布与特性参数之间的关系。理论分析了非球面镜整形原理,根据能量守恒定律和光线追迹函数推导出非球面面形表达式。考虑到加工因素,分析了影响非球面度的系统参数,根据分析,选择适当的参数,用 MATLAB 软件对映射关系和面形曲线进行数值求解并拟合得到非球面系数。用ZEMAX光学软件对整形系统进行建模,通过物理光学传播POP仿真可以得到输出光束的光强分布和传输特性,结果输出光束的平顶质量接近理论上的预期

  19. Amplitudes of solar-like oscillations in red giants: Departures from the quasi-adiabatic approximation

    Directory of Open Access Journals (Sweden)

    Barban C.

    2013-03-01

    Full Text Available CoRoT and Kepler measurements reveal us that the amplitudes of solar-like oscillations detected in red giant stars scale from stars to stars in a characteristic way. This observed scaling relation is not yet fully understood but constitutes potentially a powerful diagnostic about mode physics. Quasi-adiabatic theoretical scaling relations in terms of mode amplitudes result in systematic and large differences with the measurements performed for red giant stars. The use of a non-adiabatic intensity-velocity relation derived from a non-adiabatic pulsation code significantly reduces the discrepancy with the CoRoT measurements. The origin of the remaining difference is still unknown. Departure from adiabatic eigenfunction is a very likely explanation that is investigated in the present work using a 3D hydrodynamical model of the surface layers of a representative red giant star.

  20. A departure from cognitivism: Implications of Chomsky's second revolution in linguistics

    Science.gov (United States)

    Schoneberger, Ted

    2000-01-01

    In 1957 Noam Chomsky published Syntactic Structures, expressing views characterized as constituting a “revolution” in linguistics. Chomsky proposed that the proper subject matter of linguistics is not the utterances of speakers, but what speakers and listeners know. To that end, he theorized that what they know is a system of rules that underlie actual performance. This theory became known as transformational grammar. In subsequent versions of this theory, rules continued to play a dominant role. However, in 1980 Chomsky began a second revolution by proposing the elimination of rules in a new theory: the principles-and-parameters approach. Subsequent writings finalized the abandonment of rules. Given the centrality of rules to cognitivism, this paper argues that Chomsky's second revolution constitutes a departure from cognitivism. PMID:22477214

  1. A departure from cognitivism: Implications of Chomsky's second revolution in linguistics.

    Science.gov (United States)

    Schoneberger, T

    2000-01-01

    In 1957 Noam Chomsky published Syntactic Structures, expressing views characterized as constituting a "revolution" in linguistics. Chomsky proposed that the proper subject matter of linguistics is not the utterances of speakers, but what speakers and listeners know. To that end, he theorized that what they know is a system of rules that underlie actual performance. This theory became known as transformational grammar. In subsequent versions of this theory, rules continued to play a dominant role. However, in 1980 Chomsky began a second revolution by proposing the elimination of rules in a new theory: the principles-and-parameters approach. Subsequent writings finalized the abandonment of rules. Given the centrality of rules to cognitivism, this paper argues that Chomsky's second revolution constitutes a departure from cognitivism.

  2. Survival units as the point of departure for a relational social theory

    DEFF Research Database (Denmark)

    Kaspersen, Lars Bo; Gabriel, Norman

    makes two claims: 1) the only theoretically sustainable point of departure for a social theory is to study human beings, human society (and maybe also other animals but we leave this aside for the moment!) in a relational perspective! This claim is justified by a number of arguments among others his......Relational social theory can be found in the works of Hegel, Marx, Simmel, Mannheim, Mead, Saussure, Lévi-Strauss, Althusser, Foucault and Bourdieu. However, one of the most consistent relational thinkers is Norbert Elias. In order to develop his figurational and relational social theory Elias...... individual or a man-woman relation (family) or man-nature (subject-object). The first unit of analysis is the double relational binding of human beings in social groups. In the first order we find the relation between survival units (`state'-`state'). In a second order we find relations between families...

  3. Modelling of aspherical nebulae. I. A quick pseudo-3D photoionization code

    CERN Document Server

    Morisset, C; Peña, M

    2005-01-01

    We describe a pseudo-3D photoionization code, NEBU_3D and its associated visualization tool, VIS_NEB3D, which are able to easily and rapidly treat a wide variety of nebular geometries, by combining models obtained with a 1D photoionization code. The only requirement for the code to work is that the ionization source is uniqu e and not extended. It is applicable as long as the diffuse ionizing radiation f ield is not dominant and strongly inhomogeneous. As examples of the capabilities of these new tools, we consider two very differ ent theoretical cases. One is that of a high excitation planetary nebula that ha s an ellipsoidal shape with two polar density knots. The other one is that of a blister HII region, for which we have also constructed a spherical model (the sp herical impostor) which has exactly the same Hbeta surface brightness distrib ution as the blister model and the same ionizing star. These two examples warn against preconceived ideas when interpreting spectroscop ic and imaging data of HII regi...

  4. Depth of focus in spherical and aspheric intraocular lenses%球面与非球面人工晶状体焦深研究

    Institute of Scientific and Technical Information of China (English)

    南莉; 汤欣; 刘永基

    2012-01-01

    目的 利用眼模型研究球面和非球面人工晶状体(IOL)眼模型焦深.方法 计算机数值模拟实验研究.以Liou-Brennan眼模型为基础在ZEMAX光学设计软件中建立IOL眼模型,模拟植入不同球面和非球面IOL离焦调制传递函数(MTF)曲线,分析瞳孔、非球面设计因素对焦深的影响.结果 550 nm单色光下,球面和非球面IOL眼焦深均随瞳孔直径缩小而增加(FY60AD眼模型6 mm瞳孔1.20D,5 mm瞳孔1.35 D,4mm瞳孔1.70 D,3 mm瞳孔2.46 D; YA60BBR眼模型6 mm瞳孔1.24D,5 mm瞳孔1.48 D,4 mm瞳孔1.80 D,3mm瞳孔2.50 D),球面IOL在负离焦一侧MTF曲线较高,瞳孔直径较大时明显.5 mm瞳孔下消球差的非球面IOL眼在良好聚焦条件下MTF高于球面IOL眼,但焦深小于球面IOL眼(Tecnis Z9000为1.31 D,FY60AD为1.35 D,CeeOn911为1.55 D,YA60BBR为1.48 D),零球差IOL眼焦深降低程度较小(LI61AO为1.42 D).结论 小瞳孔下IOL眼焦深较大,大瞳孔时良好聚焦的非球面IOL眼图像质量高于球面IOL眼,但损失部分焦深,对离焦的耐受能力下降,负离焦时明显.%Objective To investigate depth of focus (DOF) in spherical and aspheric IOL eye models.Methods Computer numerical simulation experiment was used.IOL eye model based on LiouBrennan eye model was constructed by using ZEMAX optical design software.Different IOL were implanted in this eye model Monochromatic through focus modulation transfer function (MTF) curves were computed.Pupil and aspheric designs' effect on DOF were analyzed.Results DOF of eye model increased with pupil shrinkage in 550 nm monochromatic light ( FY60AD 1.20 D at 6 mm pupil,1.35 D at 5 mm pupil,1.70 D at 4 mm pupil,2.46 D at 3 mm pupil; YA60BBR 1.24 D at 6 mm pupil,1.48 D at 5 mm pupil,1.80 D at 4 mm pupil,2.50 D at 3 mm pupil).MTF in spherical IOL eye model was higher with minus defocus,this trend was obvious at larger pupil MTF of aspheric IOL eyes were higher than spherical IOL eyes when well focused at 5 mm pupil,while the

  5. Developing Intercultural Understanding for Study Abroad: Students' and Teachers' Perspectives on Pre-Departure Intercultural Learning

    Science.gov (United States)

    Holmes, P.; Bavieri, L.; Ganassin, S.

    2015-01-01

    This study reports on students' and teachers' perspectives on a programme designed to develop Erasmus students' intercultural understanding prior to going abroad. We aimed to understand how students and their teachers perceived pre-departure materials in promoting their awareness of key concepts related to interculturality (e.g.,…

  6. 75 FR 76997 - Agency Information Collection Activities: Arrival and Departure Record (Forms I-94 and I-94W) and...

    Science.gov (United States)

    2010-12-10

    ... SECURITY U.S. Customs and Border Protection Agency Information Collection Activities: Arrival and Departure Record (Forms I-94 and I-94W) and Electronic System for Travel Authorization AGENCY: U.S. Customs and...; Extension of an existing information collection: 1651-0111. SUMMARY: U.S. Customs and Border Protection...

  7. 8 CFR 215.6 - Departure from the Canal Zone, the Trust Territory of the Pacific Islands, or outlying...

    Science.gov (United States)

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Departure from the Canal Zone, the Trust Territory of the Pacific Islands, or outlying possessions of the United States. 215.6 Section 215.6 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS CONTROLS OF ALIENS DEPARTING FROM THE UNITED STATES § 215.6...

  8. 8 CFR 1215.6 - Departure from the Canal Zone, the Trust Territory of the Pacific Islands, or outlying...

    Science.gov (United States)

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Departure from the Canal Zone, the Trust Territory of the Pacific Islands, or outlying possessions of the United States. 1215.6 Section 1215.6 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION REGULATIONS CONTROLS OF ALIENS DEPARTING FROM...

  9. Using NDVI to assess departure from average greenness and its relation to fire business. Forest Service general technical report

    Energy Technology Data Exchange (ETDEWEB)

    Burgan, R.E.; Hartford, R.A.; Eidenshink, J.C.

    1996-04-01

    Satellite-derived vegetation greenness maps of the contiguous United States have been available to fire managers since 1989. This report describes a new map, departure from average, which is designed to compare current-year vegetation greenness to average greenness for the same time of year and describes it relationship to fire business.

  10. 8 CFR 212.2 - Consent to reapply for admission after deportation, removal or departure at Government expense.

    Science.gov (United States)

    2010-01-01

    ..., removal or departure at Government expense. (a) Evidence. Any alien who has been deported or removed from... who has been deported or removed from the United States and is applying for a visa, admission to the... alien deported, or removed 2 or more times, or at any time after deportation or removal in the case...

  11. Fat, weather, and date affect migratory songbirds’ departure decisions, routes, and time it takes to cross the Gulf of Mexico

    Science.gov (United States)

    Deppe, Jill L.; Ward, Michael P.; Bolus, Rachel; Diehl, Robert H.; Celis-Murillo, A.; Zenzal, Theodore J.; Moore, Frank R.; Benson, Thomas J.; Smolinsky, Jaclyn A.; Schofield, Lynn N.; Enstrom, David A.; Paxton, Eben; Bohrer, Gil; Beveroth, Tara A.; Raim, Arlo; Obringer, Renee L.; Delaney, David; Cochran, William W.

    2015-01-01

    Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson’s Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing ∼1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf.

  12. Fat, weather, and date affect migratory songbirds’ departure decisions, routes, and time it takes to cross the Gulf of Mexico

    Science.gov (United States)

    Deppe, Jill L.; Ward, Michael P.; Bolus, Rachel T.; Diehl, Robert H.; Celis-Murillo, Antonio; Zenzal, Theodore J.; Moore, Frank R.; Benson, Thomas J.; Smolinsky, Jaclyn A.; Schofield, Lynn N.; Enstrom, David A.; Paxton, Eben H.; Bohrer, Gil; Beveroth, Tara A.; Raim, Arlo; Obringer, Renee L.; Delaney, David; Cochran, William W.

    2015-01-01

    Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson’s Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing ∼1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf. PMID:26578793

  13. Conserved phenotypic variation patterns, evolution along lines of least resistance, and departure due to selection in fossil rodents.

    Science.gov (United States)

    Renaud, Sabrina; Auffray, Jean-Christophe; Michaux, Jacques

    2006-08-01

    Within a group of organisms, some morphologies are more readily generated than others due to internal developmental constraints. Such constraints can channel evolutionary changes into directions corresponding to the greatest intraspecific variation. Long-term evolutionary outputs, however, depend on the stability of these intraspecific patterns of variation over time and from the interplay between internal constraints and selective regimes. To address these questions, the relationship between the structure of phenotypic variance covariance matrices and direction of morphological evolution was investigated using teeth of fossil rodents. One lineage considered here leads to Stephanomys, a highly specialized genus characterized by a dental pattern supposedly favoring grass eating. Stephanomys evolved in the context of directional selection related to the climatic trend of global cooling causing an increasing proportion of grasslands in southwestern Europe. The initial divergence (up to approximately 6.5 mya) was channeled along the direction of greatest intraspecific variation, whereas after 6.5 mya, morphological evolution departed from the direction favored by internal constraints. This departure from the "lines of least resistance" was likely the consequence of an environmental degradation causing a selective gradient strong enough to overwhelm the constraints to phenotypic evolution. However, in a context of stabilizing selection, these constraints actually channel evolution, as exemplified by the lineage of Apodemus. This lineage retained a primitive diet and dental pattern over the last 10 myr. Limited morphological changes occurred nevertheless in accordance with the main patterns of intraspecific variation. The importance of these lines of least resistance directing long-term morphological evolution may explain parallel evolution of some dental patterns in murine evolution.

  14. Comparação da análise da frente de onda e da sensibilidade ao contraste em olhos pseudofácicos com implante de lentes intra-oculares esférica e asférica Wavefront analysis and contrast sensitivity comparison between spheric and aspheric intraocular lenses

    Directory of Open Access Journals (Sweden)

    Wilson Takashi Hida

    2008-06-01

    eyes of 16 patients. A complete ophthalmic evaluation was done before, and after surgery at days 1,3, 7 and 90, and included best corrected visual acuity, the contrast sensitivity, under photopic and mesopic conditions, and aberrometry. Almost all exams were done monocularly with undilated pupils (aberrometry under pharmacological dilatation. The patients eyes were operated with conventional phacoemulsification, with aspheric intraocular lenses in one eye, and spherical in the other. RESULTS: The visual acuity with the best correction was -0.146 in the spheric group, and -0.165 logMAR in the aspheric group in photopic conditions, and 0.024 and -0.003 LogMAR under mesopic conditions. The contrast sensitivity under photopic and mesopic conditions was similar comparing the two groups. In regard to optical aberrations there was a significant diference between the total (1.09 ± 0.56 in the aspheric, and 1.52± 1.19 in the spherical group and spherical component of high order aberrations (0.422± 0.202 in spheric group and 0.124 ± 0.087 in the aspheric group. CONCLUSION: Both groups reached excellent postoperative visual acuity in high contrast situations, however aspheric intraocular lenses group had lower total and spherical aberrations, comparing to the spheric intraocular lenses group.

  15. Asphericity in the Fermi Surface and Fermi Energy of Na-K, Na-Rb and Na-Cs Binary Alloys

    Institute of Scientific and Technical Information of China (English)

    Minal H. Patel; A.M. Vora; P.N. Gajjar; A.R. Jani

    2002-01-01

    Detailed theoretical investigations into asphericity in the Fermi surface (FS) and Fermi energy (FE) ofNa1_xKx, Na1_xRbx, and Na1_xCsx binary solid solutions are carried out for the first time. The alloying behavior ofthe K, Rb, and Cs with the Na generates the Fermi surface distortion (FSD) of bce simple metals. The FS of Na-K,Na-Rb, and Na-Cs solid solution is a distorted sphere with the largest deviation along [110]. We have found that theimpact of local-field correction function on FSD is maximun at [100] point and minimum at [111] point. The exchangeand correlation effect is found to suppress the value of FE.

  16. FIRST DIGIT DISTRIBUTION IN SOME BIOLOGICAL DATA SETS. POSSIBLE EXPLANATIONS FOR DEPARTURES FROM BENFORD'S LAW

    Directory of Open Access Journals (Sweden)

    José Luis Hernández Cáceres

    2008-01-01

    Full Text Available Aim: To explore whether the first digit law (FDL is abided by data sets from biological origin.Materials and Methods: Data were collected from different sources, including gene data length for bacteria, pre-vaccination measles incidence data and absolute values from human MEG recordings. First digit frequencies were computed and compared to predictions from FDL. Simulations included a simple model for two-dimensional epidemics spread and a randomly set upper bound model aimed to explain the behaviour of MEG data.Results: We observed that FDL is obeyed in a case of epidemic data reported at a putative focus of spread (pre-vaccination measles incidence for Preston, England. However, peculiar departures were observed for gene length distribution in microorganisms, magneto-encephalograms (MEG, and epidemic data pooled from large geographical regions.Conclusions: Simulation studies revealed that averaging data on a scenario of propagating waves can explain some of the observed distortions from FDL. This could help to understand the behaviour of epidemics data. A randomly set upper bound model (RUBM can likely explain the observed behaviour of MEG data. Explanation for gene length data behaviour requires further theoretical work.

  17. Tactile stimulations and wheel-rotation responses: Toward augmented lane departure warning systems

    Directory of Open Access Journals (Sweden)

    Christophe eTandonnet

    2014-10-01

    Full Text Available When an on-board system detects a drift of a vehicle to the left or to the right, in what way should the information be delivered to the driver? Car manufacturers have so far neglected relevant results from Experimental Psychology and Cognitive Neuroscience. Here we show that this situation possibly led to the sub-optimal design of a lane departure warning system (AFIL, PSA Peugeot Citroën implemented in commercially available automobile vehicles. Twenty participants performed a two-choice reaction time task in which they were to respond by clockwise or counter-clockwise wheel-rotations to tactile stimulations of their left or right wrist. They performed poorer when responding counter-clockwise to the right vibration and clockwise to the left vibration (incompatible mapping than when responding according to the reverse (compatible mapping. This suggests that AFIL implements the worse (incompatible mapping for the operators. This effect depended on initial practice with the interface. The present research illustrates how basic approaches in Cognitive Science may benefit to Human Factors Engineering and ultimately improve man-machine interfaces and show how initial learning can affect interference effects.

  18. How flexible is flexible? Accounting for the effect of rescheduling possibilities in choice of departure time for work trips

    DEFF Research Database (Denmark)

    Thorhauge, Mikkel; Cherchi, Elisabetta; Rich, Jeppe

    2016-01-01

    ' willingness to pay to avoid being late at work, where the presence of constraints on daily activities other than work is particularly relevant for individuals with no constraints at work. The important impact of these findings is that if we neglect the presence of constraints, as is common practise......In departure time studies it is crucial to ascertain whether or not individuals are flexible in their choices. Previous studies have found that individuals with flexible work times have a lower value of time for late arrivals. Flexibility is usually measured in terms of flexible work start time...... or in terms of constraints in arrival time at work. Although used for the same purpose, these two questions can convey different types of information. Moreover, constraints in departure time are often related not only to the main work activity, but to all daily activities. The objective of this paper...

  19. Review on departure time choice theory for highway traffic; Doro kotsu ni okeru shuppatsu jikoku sentaku ni kansuru kenkyu kaisetsu

    Energy Technology Data Exchange (ETDEWEB)

    Kuwahara, M. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science

    1998-04-01

    This paper explains theoretical results achieved to date on the fundamental theory for time smoothing which is drawing attention as a measure to mitigate traffic congestion, that is departure time choice theory for highway traffic. If a trip having a definite restriction on arrival time is used as an object of the discussion, the travel expense for a traveler consists of an expense for travel time when a car was driven at free speeds, an expense for waiting time at bottlenecks, and an expense incurred by schedule delay (s). Under an assumption that the traveler selects departure time to minimize the expense, a time-based equilibrium condition can be introduced. If a schedule expense function (f(s)) to convert `s` into an expense is convex with regard to the `s`, the first in first work (FIFW) principle can be established, that the bottleneck is reached in the order of earlier departure time that is desired. Thus, starting from handling numerically the relationship between queuing expense function in the bottleneck and the f(s), the theory developed to the multiple bottleneck and random effect theory. 19 refs., 8 figs.

  20. Timing of the departure of ocean biogeochemical cycles from the preindustrial state.

    Science.gov (United States)

    Christian, James R

    2014-01-01

    Changes in ocean chemistry and climate induced by anthropogenic CO2 affect a broad range of ocean biological and biogeochemical processes; these changes are already well underway. Direct effects of CO2 (e.g. on pH) are prominent among these, but climate model simulations with historical greenhouse gas forcing suggest that physical and biological processes only indirectly forced by CO2 (via the effect of atmospheric CO2 on climate) begin to show anthropogenically-induced trends as early as the 1920s. Dates of emergence of a number of representative ocean fields from the envelope of natural variability are calculated for global means and for spatial 'fingerprints' over a number of geographic regions. Emergence dates are consistent among these methods and insensitive to the exact choice of regions, but are generally earlier with more spatial information included. Emergence dates calculated for individual sampling stations are more variable and generally later, but means across stations are generally consistent with global emergence dates. The last sign reversal of linear trends calculated for periods of 20 or 30 years also functions as a diagnostic of emergence, and is generally consistent with other measures. The last sign reversal among 20 year trends is found to be a conservative measure (biased towards later emergence), while for 30 year trends it is found to have an early emergence bias, relative to emergence dates calculated by departure from the preindustrial mean. These results are largely independent of emission scenario, but the latest-emerging fields show a response to mitigation. A significant anthropogenic component of ocean variability has been present throughout the modern era of ocean observation.

  1. Anticancer and DNA binding activities of platinum (IV) complexes; importance of leaving group departure rate.

    Science.gov (United States)

    Pouryasin, Zahra; Yousefi, Reza; Nabavizadeh, S Masoud; Rashidi, Mehdi; Hamidizadeh, Peyman; Alavianmehr, Mohammad-Mehdi; Moosavi-Movahedi, Ali Akbar

    2014-03-01

    The two six-coordinate Pt(IV) complexes, containing bidentate nitrogen donor/methyl ligands with general formula [Pt(X)2Me2((t)bu2bpy)], where (t)bu2bpy = 4,4'-ditert-butyl-2,2'-bipyridine and X = Cl (C1) or Br (C2), serving as the leaving groups were synthesized for evaluation of their anticancer activities and DNA binding properties. To examine anticancer activities of the synthetic complexes, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and ethidium bromide/acridine orange (EB/AO) staining method were performed. The binding properties of these complexes to DNA and purine nucleotides were examined, using different spectroscopic techniques. These complexes demonstrated significant anticancer activities against three cancer cell lines Jurkat, K562, and MCF-7. On the basis of the results of EB/AO staining, C1 and C2 were also capable to induce apoptosis in cancer cells. These complexes comprise halide leaving groups, displaying different departure rates; accordingly, they demonstrated slightly dissimilar anticancer activity and significantly different DNA/purine nucleotide binding properties. The results of DNA interaction studies of these complexes suggest a mixed-binding mode, comprising partial intercalation and groove binding. Overall, the results presented herein indicate that the newly synthesized Pt(IV) complexes are promising class of the potential anticancer agents which can be considered as molecular templates in designing novel platinum anticancer drugs. This study also highlights the importance of leaving group in anticancer activity and DNA binding properties of Pt(IV) complexes.

  2. NASA's Advanced Exploration Systems Mars Transit Habitat Refinement Point of Departure Design

    Science.gov (United States)

    Simon, Matthew; Latorella, Kara; Martin, John; Cerro, Jeff; Lepsch, Roger; Jefferies, Sharon; Goodliff, Kandyce; McCleskey, Carey; Smitherman, David; Stromgren, Chel

    2017-01-01

    This paper describes the recently developed point of departure design for a long duration, reusable Mars Transit Habitat, which was established during a 2016 NASA habitat design refinement activity supporting the definition of NASA's Evolvable Mars Campaign. As part of its development of sustainable human Mars mission concepts achievable in the 2030s, the Evolvable Mars Campaign has identified desired durations and mass/dimensional limits for long duration Mars habitat designs to enable the currently assumed solar electric and chemical transportation architectures. The Advanced Exploration Systems Mars Transit Habitat Refinement Activity brought together habitat subsystem design expertise from across NASA to develop an increased fidelity, consensus design for a transit habitat within these constraints. The resulting design and data (including a mass equipment list) contained in this paper are intended to help teams across the agency and potential commercial, academic, or international partners understand: 1) the current architecture/habitat guidelines and assumptions, 2) performance targets of such a habitat (particularly in mass, volume, and power), 3) the driving technology/capability developments and architectural solutions which are necessary for achieving these targets, and 4) mass reduction opportunities and research/design needs to inform the development of future research and proposals. Data presented includes: an overview of the habitat refinement activity including motivation and process when informative; full documentation of the baseline design guidelines and assumptions; detailed mass and volume breakdowns; a moderately detailed concept of operations; a preliminary interior layout design with rationale; a list of the required capabilities necessary to enable the desired mass; and identification of any worthwhile trades/analyses which could inform future habitat design efforts. As a whole, the data in the paper show that a transit habitat meeting the 43

  3. 一种塑料非球面门镜光学系统的设计%Optical system design for plastic aspherical doorscope

    Institute of Scientific and Technical Information of China (English)

    吴福田

    2001-01-01

    介绍了一种塑料非球面门镜的设计原理及方法。 把门镜视为逆向伽俐略系统来确定外形尺 寸参数;仔细选取系统的光阑位置,选取二次曲面的系数及二次曲面的位置,可以校正系统 的参差及像散。设计的门镜比现有的多种专利门镜结构简单、成像清晰。 其视场中心像质 达到了人眼明视距离处的极限分辨率。%This paper presents the design principle and method of an optical system for pla stic aspherical doorscope. The dimension parameters are determined by viewing t h e lens as an inverse Galileo system. The coma aberation and astigmation are rec t ified through carefully selecting the position of aperture stop and the paramete rs of the quadratic surface. Compared with the methods in the available patents , design result shows that structure is simpler and imaging is clearer. The imag e quality can reach the limit of resolution at the least distance of distinct vis ion of 250 mm.

  4. Fabrication of Light Extraction Efficiency of Organic Light-Emitting Diodes with 3D Aspherical Microlens by Using Dry Etching Process

    Directory of Open Access Journals (Sweden)

    Y. C. Chen

    2013-01-01

    Full Text Available organic light-emitting diode (OLED can enable a greater artificial contrast ratio and viewing angle compared to liquid crystal display (LCD because OLED pixels directly emit light. There is a shortcoming that the internal quantum efficiency can reach values close to 100%, but about 80% light disperses because of the difference among the refractive indices of the substrate, anode, indium tin oxide (ITO film, and air. In this paper, three dimensions aspherical microlens arrays (3D A-MLAs with substrate modifications are developed to simulate the optical luminous field by using FRED software. This study modified parameters of 3D A-MLAs such as the diameter, fill-factor, aspect ratio, dry etching parameters, and electroforming rates of microlens to improve the extraction efficiency of the OLED. In dry etching, not only the aspect ratio with better extraction rate can be obtained by reactive ion etching (RIE dry etching, but also an undercutting phenomenon can be avoided. The dimensions of 3D A-MLAs can be accurately controlled in the electroforming process used to make a nickel-cobalt (Ni-Co metal mold to achieve the designed dimensions. According to the measured results, the average luminance efficacy of the OLEDs with 3D A-MLAs can be enhanced.

  5. 非球面人工晶状体植入术后患者的生存质量%Quality of life after aspheric intraocular lens implantation

    Institute of Scientific and Technical Information of China (English)

    陈风华; 曲惠红; 闫爱民

    2009-01-01

    目的 对植入非球面人工晶状体(aspherical intraocular lens,AIOL)的效果进行评价.方法 将2007年2月至2008年2月在本院行白内障超声乳化联合人工晶状体植入术患者96例随机分成AIOL组和球面人工晶状体(spherical intraocular lens,SIOL)组,并对2组患者术后满意度和生存质量进行比较.结果 AIOL组和SIOL组患者总满意率分别为42例(87.50%)和28例(58.33%),差异有显著统计学意义(P<0.01).AIOL组和SIOL组患者半年后视物舒适度及暗适应功能分值经比较,差异均有显著统计学意义(t=5.746 1,P<0.001;t=2.959 7,P<0.01).结论 AIOL值得在临床推广.

  6. Active optics and the axisymmetric case: MINITRUST wide-field three-reflection telescopes with mirrors aspherized from tulip and vase forms

    Science.gov (United States)

    Lemaitre, Gerard R.; Montiel, Pierre; Joulie, Patrice; Dohlen, Kjetil; Lanzoni, Patrick

    2004-09-01

    Wide-field astronomy requires larger size telescopes. Compared to the catadioptric Schmidt, the optical properties of a three mirror telescope provides significant advantages. (1) The flat field design is anastigmatic at any wavelength, (2) the system is extremely compact -- four times shorter than a Schmidt -- and, (3) compared to a Schmidt with refractive corrector -- requiring the polishing of three optical surfaces --, the presently proposed Modified-Rumsey design uses all of eight available free parameters of a flat fielded anastigmatic three mirror telescope for mirrors generated by active optics methods. Compared to a Rumsey design, these parameters include the additional slope continuity condition at the primary-tertiary link for in-situ stressing and aspherization from a common sphere. Then, active optics allows the polishing of only two spherical surfaces: the combined primary-tertiary mirror and the secondary mirror. All mirrors are spheroids of the hyperboloid type. This compact system is of interest for space and ground-based astronomy and allows to built larger wide-field telescopes such as demonstrated by the design and construction of identical telescopes MINITRUST-1 and -2, f/5 - 2° FOV, consisting of an in-situ stressed double vase form primary-tertiary and of a stress polished tulip form secondary. Optical tests of these telescopes, showing diffraction limited images, are presented.

  7. Explosive nucleosynthesis in the neutrino-driven aspherical supernova explosion of a non-rotating 15$M_{\\odot}$ star with solar metallicity

    CERN Document Server

    Fujimoto, Shin-ichiro; Hashimoto, Masa-aki; Ono, Masaomi; Ohnishi, Naofumi

    2011-01-01

    We investigate explosive nucleosynthesis in a non-rotating 15$M_\\odot$ star with solar metallicity that explodes by a neutrino-heating supernova (SN) mechanism aided by both standing accretion shock instability (SASI) and convection. To trigger explosions in our two-dimensional hydrodynamic simulations, we approximate the neutrino transport with a simple light-bulb scheme and systematically change the neutrino fluxes emitted from the protoneutron star. By a post-processing calculation, we evaluate abundances and masses of the SN ejecta for nuclei with the mass number $\\le 70$ employing a large nuclear reaction network. Aspherical abundance distributions, which are observed in nearby core-collapse SN remnants, are obtained for the non-rotating spherically-symmetric progenitor, due to the growth of low-mode SASI. Abundance pattern of the supernova ejecta is similar to that of the solar system for models whose masses ranges $(0.4-0.5) \\Ms$ of the ejecta from the inner region ($\\le 10,000\\km$) of the precollapse ...

  8. Usability Evaluation of Spot and Runway Departure Advisor (SARDA) Concept in Dallas/Fort Worth Airport Tower Simulation

    Science.gov (United States)

    Hayashi, Miwa; Hoang, Ty; Jung, Yoon C.; Gupta, Gautam; Malik, Waqar; Dulchinos, Victoria

    2013-01-01

    Spot and Runway Departure Advisor (SARDA) is a proposed decision-support tool for air traffic control tower controllers for reducing taxi delay and optimizing the departure sequence. In the present study, the tool's usability was evaluated to ensure that its claimed performance benefits are not being realized at the cost of increasing the work burden on controllers. For the evaluation, workload ratings and questionnaire responses collected during a human-in-the-loop simulation experiment were analyzed to assess the SARDA advisories' effects on the controllers' ratings on cognitive resources (e.g., workload, spare attention) and satisfaction. The results showed that SARDA reduced the controllers' workload and increased their spare attention. It also made workload and attention levels less susceptible to the effects of increases in the traffic load. The questionnaire responses suggested that the controllers generally were satisfied with the ease of use of the tool and the objectives of the SARDA concept, but with some caution. To gain more trust from controllers, the the reasoning behind advisories may need to be made more transparent to them.

  9. Desempenho visual após implante de uma lente intraocular asférica multifocal difrativa Visual performance after implantation of an aspheric multifocal diffractive intraocular lens

    Directory of Open Access Journals (Sweden)

    Leonardo Akaishi

    2010-08-01

    Full Text Available OBJETIVO: Avaliar a acuidade visual a distancia, intermediária e perto após o implante de uma lente intraocular (LIO asférica multifocal difrativa AcrySof® ReSTOR® SN6AD1. MÉTODOS: Estudo prospectivo de 50 pacientes com catarata submetidos à facoemulsificação e implante de LIO AcrySof® ReSTOR®. Foram avaliados acuidade visual sem correção (AVSC, acuidade visual com correção (AVCC para longe, acuidade visual para perto corrigida para longe (AVPC e acuidade visual intermediária corrigida para longe (AVIC. Um questionário de satisfação e fenômenos visuais foi administrado ao final do estudo. RESULTADO: Após três meses de cirurgia, a média das acuidades (logMAR era: AVSC, 0,05 ± 0,07; AVCC, 0,00 ± 0,01; AVPC, 0,00 ± 0,0, e AVIC, 0,15 ± 0,05. A AVCC e AVPC era de 20/25 ou melhor em todos os pacientes, sendo a AVIC J3 ou melhor em 83% dos pacientes. Pacientes relataram excelente desempenho visual nas questões relacionadas a atividades para distância, intermediário, e perto com pouca ou nenhuma dificuldade. Nenhum paciente relatou halos ou 'glare' severos, sendo os mesmos caracterizados entre nenhum a moderado. CONCLUSÃO: A LIO asférica AcrySof® ReSTOR® SN6AD1 mostrou excelentes resultados na visão para longe, perto e intermediário, além de apresentar uma baixa incidência de fenômenos visuais.PURPOSE: To evaluate distance, intermediate, and near vision after aspheric multifocal diffractive AcrySof® ReSTOR® SN6AD1 intraocular lens (IOL implantation. METHODS: Prospective study of 50 patients with cataract that had phacoemulsification and AcrySof® ReSTOR® IOL implantation. Uncorrected distance vision acuity (UDVA, corrected distance visual acuity (CDVA, distance-corrected near visual acuity (DCNVA, and distance-corrected intermediate visual acuity (DCIVA were measured postoperatively. A patient-satisfaction and visual phenomena questionnaire was administered at the end of the study. RESULTS: Three months

  10. Comparison of clinical outcomes in PRK with a standard and aspherical optimized profile: a full case analysis of 100 eyes with 1-year follow-up

    Directory of Open Access Journals (Sweden)

    Dausch D

    2014-11-01

    Full Text Available Dieter Dausch,1,2 Burglinde Dausch,2 Matthias Wottke,3 Georg Sluyterman van Langeweyde31Chung-Ang University, Seoul, South Korea; 2Augen-Laser-Klinik Nürnberg, Nuremberg, Germany; 3Carl Zeiss Meditec AG, Jena, Germany Purpose: One hundred eyes from 55 adult patients with myopia were retrospectively studied to determine the comparative safety, efficacy, and predictability of aberration smart ablation (ASA and a new advanced ablation algorithm (Triple-A using the MEL® 80 excimer laser.Methods: Fifty myopic eyes with a manifest refraction spherical equivalent (MRSE between -1.0 diopters (D and -9.75 D were consecutively treated with photorefractive keratectomy ASA, and 50 myopic eyes with an MRSE between -1.38 D and -11.0 D with photorefractive keratectomy Triple-A. Uncorrected distance visual acuity, MRSE, the absolute value of the cylinder, corrected distance visual acuity, and postoperative complications at 1 month, 3 months, 6 months, and 12 months (1 year were descriptively analyzed and compared at 1 year.Results: After 12 months, the MRSE variance was statistically significantly better in patients triaged to receive Triple-A compared with patients receiving ASA (ASA, ±0.7 D; Triple-A, ±0.15 D; P<0.001. Furthermore, no patient in the Triple-A group had any cylinder postoperatively. Patients in the Triple-A treatment arm achieved a superior result. No statistically significant difference in the two treatment arms was noted for the analysis of the mean MRSE at 12 months (P=0.78.Conclusion: Triple-A was more effective than standard aspherical surgical intervention in a number of treatment outcome parameters (eg, MRSE, astigmatism, efficacy index. The two surgical procedures were equivalent in terms of safety. Keywords: aberration smart ablation (ASA, manifest refraction spherical equivalent, Triple-A advanced ablation algorithm, uncorrected distance visual acuity, corrected distance visual acuity, excimer laser, PRK, ablation profile

  11. 亲水性非球面与球面人工晶状体植入术后高阶像差的研究%Higher order aberrations in eyes implanted with aspheric vs spherical hydrophilic intraocular lenses

    Institute of Scientific and Technical Information of China (English)

    Ibrahim Kocak; Faruk Kaya; Hakan Baybora

    2012-01-01

    AIM: To compare the effect of spherical and aspheric hydrophilic intraocular lenses (IOL) on postoperative higher order aberrations (HOA). METHODS: Uneventful phacoemulsification was performed in 78 eyes of 66 patients with implanting either spherical Softec or aspheric Ocuva lenses. Preoperative and postoperative 3rd month aberrometry was performed with Visx Wavescan aberrometer to be compared. RESULTS: There was no statistically significant difference between two groups. Postoperative root-mean-square (RMS) value of HOA: 0.27±0.11 in Softec and 0.28±0.13 in Ocuva group, spherical aberration (SA): 0.11±0.07 in Softec and 0.11±0.08 in Ocuva group. CONCLUSION: Aspheric Ocuva IOL seems not to have an advantage of decreasing postoperative HOA compared to spherical Softec IOL.%目的:比较亲水性球面和非球面人工晶状体(intraocular lenses,IOL)对术后高阶像差(higher order aberrations,HOA)的影响.方法:66例78眼行白内障超声乳化术并顺利植入球面Softec或者非球面Ocuva人工晶状体.术前和术后第3mo使用VISX Wavescan像差计进行像差测量与比较.结果:两组间统计学无显著性差异.术后的高阶像差均方根值(root-mean-square,RMS):Softec组0.27±0.11,Ocuva组0.28±0.13,球面像差(spherical aberration,SA):Softec组0.11±0.07,Ocuva组0.11±0.08.结论:与球面Softec人工晶状体比较,Ocuva非球面人工晶状体似乎没有减少术后高阶像差的优势.

  12. Marangoni凝结液珠脱离半径分析%Droplet Departure Radii for Marangoni Condensation

    Institute of Scientific and Technical Information of China (English)

    胡申华; 严俊杰; 王进仕

    2011-01-01

    An oblique copper block,which created surface temperature gradient,was designed to experimentally study the effect of macroscopic temperature gradient on Marangoni condensation of ethanol–water vapor mixtures.The experiment was carried out under a wide range of concentrations(0%-50%).For each concentration,the experiment was performed at different velocities and pressures.During the experiment condensation photographs were shot.Dropwise condensation departure radii was studied based on these photographs under the condition of different concentration,vapor-to-surface temperature difference and vapor velocity.The departure radii of dropwise condensation closely depended on the above factors.The correlation for the maximum departure radii of condensate drops was obtained on the basis of the formula for pure water vapor with velocity and Marangoni effect caused by condensation surface temperature difference.The calculation results are in good agreement with the experimental measurement over large vapor-to-surface temperature difference,and its maximum error is 23%.%为研究宏观温度梯度对Marangoni凝结的影响,设计了一个截面为梯形的试验块。在大范围的酒精气相浓度条件下(0%~50%),用实验的方法研究了宏观温度梯度对Marangoni凝结的影响。对于每个浓度都在不同蒸汽流速和压力下进行了实验并拍摄凝结图片。以凝结实验中所拍摄的实验图片为分析对象,分析不同质量分数、过冷度和流速下的凝结液珠脱离半径。凝结液珠的脱离半径与表面过冷度、凝结表面的横向温差、酒精质量分数、蒸汽流速等因素有关。以纯水的脱离半径公式为基础,考虑温差带来的Marangoni效应和蒸气流速后,拟合出Marangoni凝结凝结液珠的最大脱离半径公式,在大部分过冷度的情况下,计算值与实验数据一致性较好,最大误差为23%。

  13. 角膜地形图引导和非球面切削LASIK术后视觉质量问卷分析%Questionnaire analysis of visual quality after corneal topography guided and aspherical cutting laser in situ keratomileusis

    Institute of Scientific and Technical Information of China (English)

    闻华明; 李海祥

    2011-01-01

    satifaction ( all P < 0. 05 ) ; At high myopia, the night vision satisfaction and visual quality complaint scores mean rank of the ORK-Aph group ( 11 cases) were sperior than that of ORK-CAT groups ( 12 cases) at 1 week , 1 month and 3 months after operation ( all P < 0. 05 ) . Conclusions The visual quality is different in different customized cutting ways, there is no difference in low myopia , comeal topography guided LASIK is better for medium myopia and corneal aspherical cutting LASIK for hign myopia treatment.%目的 分析角膜地形图引导个性化LASIK和非球面切削LASIK术后视觉质量问卷调查结果 .方法 选择在遵义医学院附属医院近视眼激光治疗中心进行LASIK的患者133例(257眼),根据自愿非随机方法 分三组,其中35例(69眼)接受常规LASIK(常规组),51例(98眼)接受角膜地形图引导个性化LASIK(ORK-CAT组),另47例(90眼)接受非球面切削LASIK(ORK-Aph组).设计主观视觉质量问卷(subjective visual quality questionnaire,SVQ)调查,分别于术后1周、1个月、3个月对患者进行SVQ调查,包括夜视力满意度和视觉质量主诉评分(视朦、眩光、光晕、复视、夜视模糊等).结果 SVQ调查表明,在术后1周、1个月、3个月时,三组间夜视力满意度比较差异有统计学意义(P0.05);中度近视ORK-CAT组(25例)平均秩次在各时间段均优于ORK-Aph组(23例)和常规组(13例,均为P<0.05);高度近视在术后1周、1个月、3个月时ORK-Aph组(11例)夜视力满意度优于ORK-cAT组(12例,均为P<0.05),各时间段视觉主诉平均秩次均低于ORK-CAT组(均为P<0.05).结论 SVQ调查结果 显示:不同的优化角膜切削方式对视觉质量的影响不同,在低度近视影响无差别,ORK-CAT在中度近视显示出优越性,而ORK-Aph对高度近视治疗效果更好.

  14. Influence of departures from LTE on calcium, titanium, and iron abundance determinations in cool giants of different metallicities

    Science.gov (United States)

    Mashonkina, L. I.; Sitnova, T. N.; Pakhomov, Yu. V.

    2016-09-01

    We have performed statistical equilibrium calculations for Ca I-Ca II, Ti I-Ti II, and Fe I-Fe II by taking into account the nonequilibrium line formation conditions (the non-LTE approach) in model atmospheres of giant stars with effective temperatures 4000 K ≤ T eff ≤ 5000 K and metal abundances -4 ≤ [Fe/H] ≤ 0. The dependence of departures from LTE on atmospheric parameters has been analyzed. We present the non-LTE abundance corrections for 28 Ca I lines, 42 Ti I lines, 54 Ti II lines, and 262 Fe I lines and a three-dimensional interpolation code to obtain the non-LTE correction online for an individual line and specified atmospheric parameters.

  15. Integrated production and distribution scheduling problems related to fixed delivery departure dates and weights of late orders.

    Science.gov (United States)

    Li, Shanlin; Li, Maoqin

    2015-01-01

    We consider an integrated production and distribution scheduling problem faced by a typical make-to-order manufacturer which relies on a third-party logistics (3PL) provider for finished product delivery to customers. In the beginning of a planning horizon, the manufacturer has received a set of orders to be processed on a single production line. Completed orders are delivered to customers by a finite number of vehicles provided by the 3PL company which follows a fixed daily or weekly shipping schedule such that the vehicles have fixed departure dates which are not part of the decisions. The problem is to find a feasible schedule that minimizes one of the following objective functions when processing times and weights are oppositely ordered: (1) the total weight of late orders and (2) the number of vehicles used subject to the condition that the total weight of late orders is minimum. We show that both problems are solvable in polynomial time.

  16. Influence of departures from LTE on calcium, titanium, and iron abundance determinations in cool giants of different metallicities

    CERN Document Server

    Mashonkina, Lyudmila; Pakhomov, Yuri

    2016-01-01

    Non-local thermodynamic equilibrium (non-LTE) line formation for Ca I-Ca II, Ti I-Ti II, and Fe I-Fe II is considered in model atmospheres of giant stars with an effective temperature of 4000 K $\\le$ Teff $\\le$ 5000 K and a metal abundance of -4 $\\le$ [Fe/H] $\\le$ 0. The departures from LTE are analyzed depending on atmospheric parameters. We present the non-LTE abundance corrections for 28 lines of Ca I, 42 lines of Ti I, 54 lines of Ti II, and 262 lines of Fe I and a three-dimensional interpolation code to obtain the non-LTE correction online (http://spectrum.inasan.ru/nLTE/) for an individual spectral line and given atmospheric parameters.

  17. The effectiveness of lane departure warning systems-A reduction in real-world passenger car injury crashes.

    Science.gov (United States)

    Sternlund, Simon; Strandroth, Johan; Rizzi, Matteo; Lie, Anders; Tingvall, Claes

    2017-02-17

    The objective of this study was to estimate the safety benefits of in vehicle lane departure warning (LDW) and lane keeping aid (LKA) systems in reducing relevant real-world passenger car injury crashes. The study used an induced exposure method, where LDW/LKA-sensitive and nonsensitive crashes were compared for Volvo passenger cars equipped with and without LDW/LKA systems. These crashes were matched by car make, model, model year, and technical equipment; that is, low-speed autonomous emergency braking (AEB) called City Safety (CS). The data were extracted from the Swedish Traffic Accident Data Acquisition database (STRADA) and consisted of 1,853 driver injury crashes that involved 146 LDW-equipped cars, 11 LKA-equipped cars, and 1,696 cars without LDW/LKA systems. The analysis showed a positive effect of the LDW/LKA systems in reducing lane departure crashes. The LDW/LKA systems were estimated to reduce head-on and single-vehicle injury crashes on Swedish roads with speed limits between 70 and 120 km/h and with dry or wet road surfaces (i.e., not covered by ice or snow) by 53% with a lower limit of 11% (95% confidence interval [CI]). This reduction corresponded to a reduction of 30% with a lower limit of 6% (95% CI) for all head-on and single-vehicle driver injury crashes (including all speed limits and all road surface conditions). LDW/LKA systems were estimated to lower the driver injury risk in crash types that the systems are designed to prevent; that is, head-on and single-vehicle crashes. Though these are important findings, they were based on a small data set. Therefore, further research is desirable to evaluate the effectiveness of LDW/LKA systems under real-world conditions and to differentiate the effectiveness between technical solutions (i.e., LDW and LKA) proposed by different manufacturers.

  18. Unravelling the Structure of Aspherical Protoplanetary Nebulae I. HST Imaging and OH Maser-Line Observations of Roberts 22

    Science.gov (United States)

    Sahai, R.; Zijlstra, A.; Bujarrabal, V.; Hekkert, P. L.

    1998-01-01

    We have obtained high-resolution wide-band, narrow-band and polarimetric images of the bipolar protoplanetary nebula Roberts 22 with the Wide-Field & Planetary Camera 2 on HST. OH maser-line emission has also been observed using the Australia Telescope Compact Array.

  19. “福家双星”——Voigtlander Nokton 35mm f/1.2 Aspherical Color-Skopar 35mm f/2.5 PⅡ 试用手记

    Institute of Scientific and Technical Information of China (English)

    陈彦

    2004-01-01

    35mm焦段是广受欢迎的旁轴相机镜头,因此成为各厂商显示镜头制造水平的标准,当Leica迷们还在津津乐道Summilux-M 35mm f/1.4 ASPH和Summilux-M 35mm f/2 ASPH该如何取舍时,福伦达(Voigtlander)Nokton 35mm f/1.2 Aspherical 和Color-Skopar 35mm f/2.5 PⅡ已经悄悄地挂在一部分旁轴爱好者的嘴边和器材城的柜台上了。细算一下,加上福伦达Ultron 35mm f/1.7 Aspherical,Color-Skopar 35mm f/2.5 C和Color-Skopar 35mm f/2.5P及搭配在Bessa-R2S/R2C 上的SC Skopar 35mm f/2.5,确善能公司(Cosina)已经推出了六款福伦35mm小广角旁轴镜头了,真是不遗余力。

  20. Effect of aspherical and yellow tinted intraocular lens on blue-on-yellow perimetry Efeito das lentes intraoculares asféricas e com pigmentação amarela na campimetria azul-amarelo

    Directory of Open Access Journals (Sweden)

    Rodrigo França de Espíndola

    2012-10-01

    Full Text Available PURPOSE: To investigate the possible effect of aspherical or yellow tinted intraocular lens (IOL on contrast sensitivity and blue-on-yellow perimetry. METHODS: This prospective randomized bilateral double-masked clinical study included 52 patients with visually significant bilateral cataracts divided in two groups; 25 patients (50 eyes received aspherical intraocular lens in one eye and spherical intraocular lens in the fellow eye; and 27 patients (54 eyes received ultraviolet and blue light filter (yellow tinted IOL implantation in one eye and acrylic ultraviolet filter IOL in the fellow eye. The primary outcome measures were contrast sensitivity and blue-on-yellow perimetry values (mean deviation [MD] and pattern standard deviation [PSD] investigated two years after surgery. The results were compared intra-individually. RESULTS: There was a statistically significant between-group (aspherical and spherical intraocular lens difference in contrast sensitivity under photopic conditions at 12 cycles per degree and under mesopic conditions at all spatial frequencies. There were no between-group significant differences (yellow tinted and clear intraocular lens under photopic or mesopic conditions. There was no statistically significant difference between all intraocular lens in MD or PSD. CONCLUSION: Contrast sensitivity was better under mesopic conditions with aspherical intraocular lens. Blue-on-yellow perimetry did not appear to be affected by aspherical or yellow tinted intraocular lens. Further studies with a larger sample should be carried out to confirm or not that hypotheses.OBJETIVO: Investigar a possibilidade de efeitos na sensibilidade ao contraste e nos resultados da campimetria azul-amarelo com implante de uma lente intraocular (LIO asférica ou de pigmentação amarela. MÉTODOS: Trata-se de um estudo prospectivo, randomizado, duplo-mascarado, envolvendo 52 pacientes portadores de catarata senil bilateral, divididos em dois grupos; 25

  1. Comparison of toxicogenomics and traditional approaches to inform mode of action and points of departure in human health risk assessment of benzo[a]pyrene in drinking water

    Science.gov (United States)

    Labib, Sarah; Bourdon-Lacombe, Julie; Kuo, Byron; Buick, Julie K.; Lemieux, France; Williams, Andrew; Halappanavar, Sabina; Malik, Amal; Luijten, Mirjam; Aubrecht, Jiri; Hyduke, Daniel R.; Fornace, Albert J.; Swartz, Carol D.; Recio, Leslie; Yauk, Carole L.

    2015-01-01

    Toxicogenomics is proposed to be a useful tool in human health risk assessment. However, a systematic comparison of traditional risk assessment approaches with those applying toxicogenomics has never been done. We conducted a case study to evaluate the utility of toxicogenomics in the risk assessment of benzo[a]pyrene (BaP), a well-studied carcinogen, for drinking water exposures. Our study was intended to compare methodologies, not to evaluate drinking water safety. We compared traditional (RA1), genomics-informed (RA2) and genomics-only (RA3) approaches. RA2 and RA3 applied toxicogenomics data from human cell cultures and mice exposed to BaP to determine if these data could provide insight into BaP's mode of action (MOA) and derive tissue-specific points of departure (POD). Our global gene expression analysis supported that BaP is genotoxic in mice and allowed the development of a detailed MOA. Toxicogenomics analysis in human lymphoblastoid TK6 cells demonstrated a high degree of consistency in perturbed pathways with animal tissues. Quantitatively, the PODs for traditional and transcriptional approaches were similar (liver 1.2 vs. 1.0 mg/kg-bw/day; lung 0.8 vs. 3.7 mg/kg-bw/day; forestomach 0.5 vs. 7.4 mg/kg-bw/day). RA3, which applied toxicogenomics in the absence of apical toxicology data, demonstrates that this approach provides useful information in data-poor situations. Overall, our study supports the use of toxicogenomics as a relatively fast and cost-effective tool for hazard identification, preliminary evaluation of potential carcinogens, and carcinogenic potency, in addition to identifying current limitations and practical questions for future work. PMID:25605026

  2. A Departure from prediction: Electroweak physics at NuTeV

    Energy Technology Data Exchange (ETDEWEB)

    K. S. McFarland et al.

    2004-01-12

    The NuTeV experiment has performed precision measurements of the ratio of neutral-current to charged-current cross-sections in high rate, high energy neutrino and antineutrino beams on a dense, primarily steel, target. The separate neutrino and anti-neutrino beams, high statistics, and improved control of other experimental systematics, allow the determination of electroweak parameters with significantly greater precision than past {nu}N scattering experiments. Our null hypothesis test of the standard model prediction measures sin{sup 2} {theta}{sub W}{sup (on shell)} = 0.2277 {+-} 0.0013(stat) {+-} 0.0009(syst), a value which is 3.0{sigma} above the prediction. We discuss possible explanations for and implications of this discrepancy.

  3. SMEs and Electronic Commerce: A Departure from the Traditional Prioritisation of Training?

    Science.gov (United States)

    Barry, Helen; Milner, Brigid

    2002-01-01

    A survey of 56 small/medium-sized Irish enterprises showed that 46% were highly proficient in electronic commerce, 42% were at the basic level. Media pressure significantly influenced adoption. In 40% of firms, owner-managers were the driving force. E-commerce was not yet business critical and relevant training was not yet a comprehensive…

  4. SMEs and Electronic Commerce: A Departure from the Traditional Prioritisation of Training?

    Science.gov (United States)

    Barry, Helen; Milner, Brigid

    2002-01-01

    A survey of 56 small/medium-sized Irish enterprises showed that 46% were highly proficient in electronic commerce, 42% were at the basic level. Media pressure significantly influenced adoption. In 40% of firms, owner-managers were the driving force. E-commerce was not yet business critical and relevant training was not yet a comprehensive…

  5. Integrated Production and Distribution Scheduling Problems Related to Fixed Delivery Departure Dates and Weights of Late Orders

    Directory of Open Access Journals (Sweden)

    Shanlin Li

    2015-01-01

    Full Text Available We consider an integrated production and distribution scheduling problem faced by a typical make-to-order manufacturer which relies on a third-party logistics (3PL provider for finished product delivery to customers. In the beginning of a planning horizon, the manufacturer has received a set of orders to be processed on a single production line. Completed orders are delivered to customers by a finite number of vehicles provided by the 3PL company which follows a fixed daily or weekly shipping schedule such that the vehicles have fixed departure dates which are not part of the decisions. The problem is to find a feasible schedule that minimizes one of the following objective functions when processing times and weights are oppositely ordered: (1 the total weight of late orders and (2 the number of vehicles used subject to the condition that the total weight of late orders is minimum. We show that both problems are solvable in polynomial time.

  6. Simulation of the Electric Signal During the Formation and Departure of Droplets in the Electroslag Remelting Process

    Science.gov (United States)

    Kharicha, A.; Wu, M.; Ludwig, A.; Karimi-Sibaki, E.

    2016-04-01

    In the ESR process, it is very difficult to make experimental observations of the phenomena occurring within the molten slag. At present, the state of the process is solely evaluated from the variation of the measured electric variables. The present paper proposes the use of 3D numerical model to explore the complex coupling existing between the electrodynamics and the phase distribution during the process. The droplet formation during melting of an electrode under the action of a strong DC current is simulated with a multiphase-magnetohydrodynamic approach. A volume-of-fluid approach is used for the interface tracking, and the potential formulation is used to determine the electric and magnetic fields. The Lorentz force and the Joule heating are recalculated at each time step as a function of the phase distribution. The evolution of the electric resistance of the system during the droplet formation and departure is reported. The results are compared with the measurements made in experimental and industrial-scale ESR processes. Two values of metal/slag interfacial tension of 1 and 0.1 N m-1 are explored. The effects of the control system as well as the presence of a horizontal magnetic field are also investigated. These results open the possibility to link online the voltage signal variation with real physical phenomena happening during the process.

  7. Individual differences in cognitive functioning predict effectiveness of a heads-up lane departure warning for younger and older drivers.

    Science.gov (United States)

    Aksan, Nazan; Sager, Lauren; Hacker, Sarah; Lester, Benjamin; Dawson, Jeffrey; Rizzo, Matthew; Ebe, Kazutoshi; Foley, James

    2017-02-01

    The effectiveness of an idealized lane departure warning (LDW) was evaluated in an interactive fixed base driving simulator. Thirty-eight older (mean age=77years) and 40 younger drivers (mean age=35years) took four different drives/routes similar in road culture composition and hazards encountered with and without LDW. The four drives were administered over visits separated approximately by two weeks to examine changes in long-term effectiveness of LDW. Performance metrics were number of LDW activations and average correction time to each LDW. LDW reduced correction time to re-center the vehicle by 1.34s on average (95% CI=1.12-1.57s) but did not reduce the number of times the drivers drifted enough in their lanes to activate the system (LDW activations). The magnitude of reductions in average correction RT was similar for older and younger drivers and did not change with repeated exposures across visits. The contribution of individual differences in basic visual and motor function, as well as cognitive function to safety gains from LDW was also examined. Cognitive speed of processing predicted lane keeping performance for older and younger drivers. Differences in memory, visuospatial construction, and executive function tended to predict performance differences among older but not younger drivers. Cognitive functioning did not predict changes in the magnitude of safety benefits from LDW over time. Implications are discussed with respect to real-world safety systems.

  8. Modelling Airport Efficiency With Distributions Of The Inefficient Error Term: An Application Of Time Series Data For Aircraft Departure Delay

    Directory of Open Access Journals (Sweden)

    Ronald Wesonga

    2013-04-01

    Full Text Available The study employs determinants of the aircraft departure delay to estimate airport efficiency. Two main parameters were applied to fit the stochastic frontier model using transcendental logarithmic function where both frontier and inefficiency models were generated. The estimated airport efficiencies over a period of 1827 days applying the half-normal and exponential distributions for the inefficiency error terms were (0.7498; δ=0.1417, n=1827 and (0.8181; δ=0.1224, n=1827 respectively. The correlation coefficient for the efficiency estimates (ρ=0.9791, n=1827, p<0.05 between the half-normal and exponential distributions showed no significant statistical difference. Further analysis showed that airport inefficiency was significantly associated with higher number of persons on board, lower visibility level, lower air pressure tendency, higher wind speed and a higher proportion of arrival aircraft delays. The study offers a contribution towards assessing the dynamics for the distribution of inefficient error term to estimate airport efficiency by employing both meteorological and aviation parameters. The study recommends that although either half-normal or exponential distributions could be used; the exponential distribution for the error term was found more suitable when estimating the efficiency score for the airport.

  9. Comparación del LASIK convencional y el LASIK asférico en el tratamiento de la ametropía Comparison of conventional LASIK and aspheric LASIK in the treatment of ametropia

    Directory of Open Access Journals (Sweden)

    Yanaisa Riverón Ruiz

    2012-12-01

    Full Text Available Objetivo: comparar los resultados del LASIK con patrón de ablación convencional y el asférico en la corrección de ametropías y evaluar la sensibilidad al contraste en ambos procedimientos. Métodos: se realizó un estudio comparativo y prospectivo en 64 pacientes de la consulta externa del Servicio de Cirugía Refractiva del Instituto Cubano de Oftalmología "Ramón Pando Ferrer". Estos fueron distribuidos aleatoriamente en dos grupos iguales para ambas técnicas. Las variables estudiadas fueron agudeza visual sin corrección y mejor corregida, aberración y sensibilidad al contraste en condiciones fotópicas. Resultados: la agudeza visual sin corrección mejoró ocho líneas en la cartilla de Snellen, sin diferencias entre ambos procedimientos. La aberración esférica presentó un valor medio inferior en el tratamiento asférico (0,30. Se encontró una disminución de la sensibilidad al contraste después del tratamiento convencional. Conclusiones: ambas técnicas quirúrgicas mantienen una buena agudeza visual con corrección y sin esta, después de la cirugía en ambientes fotópicos. La calidad visual del tratamiento asférico es superior, al inducir menor aberración esférica y mejor sensibilidad al contraste después de cirugía.Objective: to compare the results obtained with the LASIK using both conventional and aspheric patterns to correct ametropies and to evaluate the contrast sensitivity after these two procedures. Methods: a comparative and prospective study was conducted in 64 patients who attended the refractive surgery outpatient service of “Ramon Pando Ferrer” Cuban Institute of Ophthalmology. They were randomly distributed in two groups for both procedures. Several variables were studied such as: uncorrected visual acuity, best corrected visual acuity, aberration and contrast sensitivity at photopic conditions. Results: uncorrected visual acuity improved 8 lines in the Snellen’s chart, without significant

  10. Multilocus sequence data reveal extensive departures from equilibrium in domesticated tomato (Solanum lycopersicum L.).

    Science.gov (United States)

    Labate, J A; Robertson, L D; Baldo, A M

    2009-09-01

    Limited genetic variation has been observed within tomato (Solanum lycopersicum L.), although no studies have extensively surveyed single nucleotide polymorphism (SNP) diversity among tomato landraces. We estimated intraspecific DNA sequence variation by analyzing 50 gene fragments (23.2 kb) per plant in a 31 plant diversity panel. The majority of loci (80%) were polymorphic with the minor allele at a frequency of 10% or less for most (141 of 155) SNPs. Mean diversity as estimated by theta and pi was approximately 1.5 SNPs per kb. Significant linkage disequilibrium was observed between 19% of locus pairs, and within-locus population recombination estimates were negligible. We also sequenced 43 gene fragments from wild tomato Solanum arcanum Peralta as an outgroup. Various statistical tests rejected a neutral equilibrium model of molecular evolution at 10 of 50 loci. Rare, highly diverged alleles were observed, involving at least seven tomato lines and five loci. Some of these may represent introgressions that originated both from natural hybridization with Solanum pimpinellifolium L. and from crosses with S. pimpinellifolium and additional wild relatives for crop improvement. The former was reported from classical field studies carried out by CM Rick; the latter has been extensively documented in the crop, particularly for transfer of disease resistance alleles. Extensive introgression and frequent bottlenecks within S. lycopersicum will pose a challenge to reconstructing the genetic bases of domestication and selection using methods that rely on patterns of molecular polymorphism.

  11. Measuring chess experts' single-use sequence knowledge: an archival study of departure from 'theoretical' openings.

    Directory of Open Access Journals (Sweden)

    Philippe Chassy

    Full Text Available The respective roles of knowledge and search have received considerable attention in the literature on expertise. However, most of the evidence on knowledge has been indirect--e.g., by inferring the presence of chunks in long-term memory from performance in memory recall tasks. Here we provide direct estimates of the amount of monochrestic (single use and rote knowledge held by chess players of varying skill levels. From a large chess database, we analyzed 76,562 games played in 2008 by individuals ranging from Class B players (average players to Masters to measure the extent to which players deviate from previously known initial sequences of moves ("openings". Substantial differences were found in the number of moves known by players of different skill levels, with more expert players knowing more moves. Combined with assumptions independently made about the branching factor in master games, we estimate that masters have memorized about 100,000 opening moves. Our results support the hypothesis that monochrestic knowledge is essential for reaching high levels of expertise in chess. They provide a direct, quantitative estimate of the number of opening moves that players have to know to reach master level.

  12. Viability effects and not meoitic drive cause dramatic departures from Mendelian inheritance for malic enzyme in hybrids of Tigriopus californicus populations.

    Science.gov (United States)

    Willett, C S; Berkowitz, J N

    2007-05-01

    The genetic basis of post-zygotic reproductive isolation is beginning to be untangled in closely related species, but less is known about the genetics of reproductive isolation between divergent populations. Here, two genes encoding malic enzyme (ME) are isolated from the copepod Tigriopus californicus and their influence upon lowered viability in F(2) hybrids of genetically divergent populations is determined. Each ME gene has diverged extensively between T. californicus populations and one gene shows evidence for a recent selective sweep. Segregation patterns of genotypes for both ME genes in adult F(2) hybrids reveal dramatic departures from Mendelian inheritance, deviations that are not seen in F(2) nauplii implying that selection is acting during development based upon the genotype at these ME genes. These results imply that selection against deleterious gene combinations and not aberrant segregation (i.e. meiotic drive) is likely to lead to dramatic departures from Mendelian inheritance observed in these crosses.

  13. Departure from multiplicative interaction for catechol-O-methyltransferase genotype and active/passive exposure to tobacco smoke among women with breast cancer

    Directory of Open Access Journals (Sweden)

    Wilk Jemma

    2006-01-01

    Full Text Available Abstract Background Women with homozygous polymorphic alleles of catechol-O-methyltransferase (COMT-LL metabolize 2-hydroxylated estradiol, a suspected anticarcinogenic metabolite of estrogen, at a four-fold lower rate than women with no polymorphic alleles (COMT-HH or heterozygous women (COMT-HL. We hypothesized that COMT-LL women exposed actively or passively to tobacco smoke would have higher exposure to 2-hydroxylated estradiol than never-active/never passive exposed women, and should therefore have a lower risk of breast cancer than women exposed to tobacco smoke or with higher COMT activity. Methods We used a case-only design to evaluate departure from multiplicative interaction between COMT genotype and smoking status. We identified 502 cases of invasive incident breast cancer and characterized COMT genotype. Information on tobacco use and other potential breast cancer risk factors were obtained by structured interviews. Results We observed moderate departure from multiplicative interaction for COMT-HL genotype and history of ever-active smoking (adjusted odds ratio [aOR] = 1.6, 95% confidence interval [CI]: 0.7, 3.8 and more pronounced departure for women who smoked 40 or more years (aOR = 2.3, 95% CI: 0.8, 7.0. We observed considerable departure from multiplicative interaction for COMT-HL genotype and history of ever-passive smoking (aOR = 2.0, 95% CI: 0.8, 5.2 or for having lived with a smoker after age 20 (aOR = 2.8, 95% CI: 0.8, 10. Conclusion With greater control over potential misclassification errors and a large case-only population, we found evidence to support an interaction between COMT genotype and tobacco smoke exposure in breast cancer etiology.

  14. Binocular clinical comparison study of Tecnis multifocal aspheric and monofocal spherical intraocular lenses%双眼植入Tecnis多焦点和单焦点球面人工晶状体的临床比较研究

    Institute of Scientific and Technical Information of China (English)

    叶盼盼; 姚克; 李霞; 吴炜; 黄晓丹; 俞一波

    2010-01-01

    pseudophakic patients with bilateral implantation of Tecnis multifocal aspheric and conventional monofocal spherical intraocular lenses (IOL). Methods A prospective study of 100 consecutive cases (200 eyes) was conducted. All cataract patients underwent phaocoemulsification were randomized to receive multifocal aspheric IOL ( Tecnis ZM900, AMO, multifocal aspheric group) or conventional spherical IOL ( Akreos Adapt, Bausch&Lomb, monofocal spherical group) . The following investigations were performed to assess the uncorrected and distance-corrected visual acuity of distance, intermediate and near distances, accommodative amplitude, spherical aberrations of total eye, contrast sensitivity, glare sensitivity and near stereoacuity. Patients were surveyed for visual disturbances and lifestyle visual quality. The independent-samples t test waa used to compare the measure data which met normal distribution and the Mann-Whitney U test was used to compare the measure data which didn' t meet. The chi-square test was applied to compare categorical variables. Results The uncorrected and distance-corrected bilateral visual acuity of multifocal aspheric group at 30 cm and 40 cm were 0. 24 ± 0. 12 and 0. 22 ± 0. 11 (logMAR) , better than monofocal spherical group ( Z = - 8. 261, P = 0. 000;Z = -5. 508, P =0.000), but the visual acuity at other distances had no statistical difference between two groups. Patients with multifocal aspheric IOL had significantly higher accommodative amplitude than those with monofcal spherical IOL, improved about 2. 3 - 2. 8 D ( Z= -10. 655, P = 0. 000; Z =- 2. 709, P = 0. 007). Mean spherical aberration of multifocal aspheric group was ( 0. 027 ±0. 160) μm and (0. 006 ±0. 083)μm, significantly lower than that of monofocal spherical group (0. 269 ±0. 161) μm, (0.037 ±0.205) μm at 5 mm and 3 mm pupil diameter(Z= - 8. 815, P = 0. 000; Z = -2. 791, P = 0. 005) . The difference of contrast sensitivity was not significant, but glare sensitivity was higher

  15. Evaluation of the benchmark dose for point of departure determination for a variety of chemical classes in applied regulatory settings.

    Science.gov (United States)

    Izadi, Hoda; Grundy, Jean E; Bose, Ranjan

    2012-05-01

    Repeated-dose studies received by the New Substances Assessment and Control Bureau (NSACB) of Health Canada are used to provide hazard information toward risk calculation. These studies provide a point of departure (POD), traditionally the NOAEL or LOAEL, which is used to extrapolate the quantity of substance above which adverse effects can be expected in humans. This project explored the use of benchmark dose (BMD) modeling as an alternative to this approach for studies with few dose groups. Continuous data from oral repeated-dose studies for chemicals previously assessed by NSACB were reanalyzed using U.S. EPA benchmark dose software (BMDS) to determine the BMD and BMD 95% lower confidence limit (BMDL(05) ) for each endpoint critical to NOAEL or LOAEL determination for each chemical. Endpoint-specific benchmark dose-response levels , indicative of adversity, were consistently applied. An overall BMD and BMDL(05) were calculated for each chemical using the geometric mean. The POD obtained from benchmark analysis was then compared with the traditional toxicity thresholds originally used for risk assessment. The BMD and BMDL(05) generally were higher than the NOAEL, but lower than the LOAEL. BMDL(05) was generally constant at 57% of the BMD. Benchmark provided a clear advantage in health risk assessment when a LOAEL was the only POD identified, or when dose groups were widely distributed. Although the benchmark method cannot always be applied, in the selected studies with few dose groups it provided a more accurate estimate of the real no-adverse-effect level of a substance.

  16. High-Speed Visualization of Bubble Behaviors for Pool Boiling of R-141b

    Institute of Scientific and Technical Information of China (English)

    Yanhua DIAO; Yaohua ZHAO; Qiuliang WANG

    2006-01-01

    A visualization study on the behavior of bubbles has been carried out for pool boiling of R141b on a horizontal transparent heater at pressure 0.1 MPa. The behaviors of bubbles were recorded by a high-speed camera placed beneath the heater surface. The departure diameter, departure time of bubbles and nucleation site density at different heat flux were obtained. The visualization results show that bubble departure diameter and departure time decrease, while the nucleation site density increases as the heat flux increases. It is also observed that there is no liquid recruited into the microlayer in the experiment. Based on the experimental results, boiling curve for R141b was predicted by using the dynamic microlayer model. As a result, the agreement between the predictive result based on the dynamic microlayer model and the experiment data for boiling curve of R141b is good at high heat flux.

  17. Departure Roger Anthoine

    CERN Multimedia

    Schopper,H

    1986-01-01

    Remerciements et discours du D.G. H.Schopper à l'occasion du départ de Roger Anthoine (attaché de presse), qui travaillait dans la communication et quitte le Cern après 27 ans de service. Il gardait des relations avec des médias internationaux et la presse locale; remise des cadeaux: album photo avec images des musés de Genève et un radio aviation; R.A. fait un résumé de ses activités et souvenirs et remercie ses collaborateurs

  18. CERN Council Meeting : British Under Secretary of State, Robert Jackson, underlines U.K. interest in CERN's future : decisions on CERN Review Committee recommendations : early departure scheme for at least 200 employees - Member States' contributions to be updated

    CERN Multimedia

    CERN Press Office. Geneva

    1988-01-01

    CERN Council Meeting : British Under Secretary of State, Robert Jackson, underlines U.K. interest in CERN's future : decisions on CERN Review Committee recommendations : early departure scheme for at least 200 employees - Member States' contributions to be updated

  19. Odisea de Kazantzakis Itaca, punto de llegada y de partida Kazantzakis' Odyssey. Ithaca, point of arrival and departure

    Directory of Open Access Journals (Sweden)

    Miguel Castillo Didier

    2010-01-01

    Full Text Available Odiseo llegó a Itaca en el texto de Homero y también en la Odisea moderna. En realidad, ya había llegado ya cuando se inicia el nuevo poema. Itaca conserva la simbología que tuvo en el texto homérico, pero adquiere un nuevo rol. En la isla, Odiseo reafirma su identidad: es el mismo héroe que participó en la guerra de Troya y después luchó contra adversidades y tentaciones durante diez años, sin perder la voluntad de retornar a la tierra y al hogar. Reconoce su territorio, sepulta a su padre, casa a su hijo. Pero, además, ahora es el punto de partida. Desde ella sale Odiseo en el nuevo viaje, acaso más largo que el antiguo y sin regreso. La isla amada sigue siendo la isla amada. Amándola, la deja el antiguo héroe. Y en su larguísima travesía hacia la muerte en los hielos antarticos, la recuerda no pocas veces.Odysseus reaches Ithaca in the Homeric text and also in the modern Odyssey. He had really reached there when the new poem begins. Ithaca preserves the symbology which had in the Homeric text, but it acquires a new role. In the island, Odysseus reaffirms his identity: he is the same hero who participated in theTrojan war, fought against adversities and temptation for ten years, without losing the will to return to his land and home. He recognizes his territory, buries his father and accompanies his son in the latter s wedding. Now it is also the point of departure: Odysseus sails from it in a new voyage, perhaps longer than the previous one and with no return. The beloved island remains as such. Loving it, the hero abandons it. In his very long voyage to death on he Antarctic ices he often remembers it.

  20. Departure Time Choice Behavior Based on Bounded Rationality%有限理性下个体出发时间选择行为研究

    Institute of Scientific and Technical Information of China (English)

    栾琨; 傅忠宁; 隽志才

    2016-01-01

    Subject to such limitations as cognitive ability and logical reasoning ability, it is difficult for individual to be perfectly rational in the travel decision-making process. Taking departure time choice as an example, key behavior factors such as spatial knowledge acquisition, learning, cognition update and solution search are introduced. The theoretical framework of travel decision-making process is built based on bounded rationality. Departure time behavioral intention survey program is designed by integration of RP and SP survey methods. Individual’s knowledge representation is studied, and cognitive update is completed by using Bayesian learning theory. Functions of search cost and search gain are defined. By using survey data, departure time heuristic search rules and decision rules are derived based on PART and RIPPER algorithm separately. The results show that there exist perception threshold in individual’s departure time choice behavior under bounded rationality, rather than seeking global optimal solution.%个体受限于认知能力和逻辑推理能力的限制,在出行决策过程中很难做到完全理性。本文以出发时间选择为例,在有限理性行为假设基础上,引入空间知识获取、学习及认知更新和方案搜索等关键行为要素,构建有限理性下的出行决策过程理论框架。融合RP和SP调查方法,设计出发时间选择行为意向调查方案。研究个体知识的表达方式,应用贝叶斯学习理论完成认知更新。定义搜索成本和收益函数,利用调查数据分别提取基于PART和RIPPER算法的出发时间启发式搜索规则和决策规则。结果表明,有限理性下个体出发时间选择行为存在感知阈值,而并非寻求全局最优解。

  1. Horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications.

    Science.gov (United States)

    Ma, Hongcai; Wu, Lin

    2015-07-10

    We present the design of a horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications. This solar concentrator consists of an array of telecentric primary concentrators, a horizontally staggered lightguide layer, and a vertically tapered lightguide layer. The primary concentrator is realized by two plano-aspheric lenses with lateral movement and maintains a high F-number over an angle range of ±23.5°. The results of the simulations show that the solar concentrator achieves a high concentration ratio of 500× with ±0.5° of acceptance angle by a single-axis tracker and dual lateral translation stages.

  2. Photoemission studies of high-temperature superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Margaritondo, G. (Inst. de Physique Appliquee, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (CH))

    1990-11-01

    Photoemission spectroscopy has recently emerged as one of the leading techniques in the study of high-temperature superconductors. Relevant successes include the direct detection of the superconductivity gap, tests for departure from Fermi-liquid behavior, and many interface chemical studies with technological interest. The authors present a review of the fundamental and applied aspects of this technique.

  3. 终极控制股东两权偏离、替代效应与公司价值%Rights Departure of Ultimate Controlling Shareholders,Substitution Effect and Firm Performance

    Institute of Scientific and Technical Information of China (English)

    张耀伟

    2011-01-01

    significantly negative effect on corporate performance. Ultimate controlling shareholders can get more controlling rights in comparison with its cash flow rights, especially in the high level of rights departure. Third, improved corporate governance has significant positive effect on corporate performance, and has significant mediating effect between rights departure and firm performance.The biggest shareholder has absolute controlling rights. Optimizing corporate governance should pay more attention to building competitive ownership structure, improving top managers' incentives and restrictive mechanisms, and strengthening information disclosure. The revenue is higher and the cost is lower because governance mechanisms have stronger substitution effect with board governance. We should limit the control levels of ultimate controlling shareholders to cash flow rights. Doing so can increase positive effect on public corporate performance and lessen exploitation behaviors.

  4. Cockroach control methods for departure trains in Wuhan%武汉始发列车蟑螂防治方法的研究

    Institute of Scientific and Technical Information of China (English)

    邹建国; 殷璐; 李春生; 戴兆明

    2011-01-01

    Objective To control cockroaches density on trains effectively. Methods Cockroach species and density were investigated by irritating cockroaches with pyrethrum spray. Fumigation, residual spray, gel bait,poison bait and ULV spray were used to control the cockroaches, then their control effects were studied. Results The component ratio of German cockroach on departure trains in Wuhan was 91.60% - 94.46%. Cockroach infestation rate of high grade to low grade trains increased from 6.85% to 37.69%. The one week killing rates of fumigation or residual spray treated merely were 82. 35% - 100%, but the cockroach densities restored rapidly in 2 months.While treated regularly with residual spray, gel bait and poison bait, the one week killing rates were 91.94% -100% ,and low densities of cockroach were keeped in 2 months. 48 h killing rates of emergent treat with ULV spray and fumigation were 95.83% and 87.69% respectively,it cost RMB 28 and 40 per carriage. Conclusion Cockroaches density on trains can be controlled in low level when treating regularly with residual spray, gel bait and poison bait. High density of cockroaches on trains can be cotrolled with emergent treat with ULV spray, it has advantage over fumigation both in irritation and safety.%目的 科学有效地控制列车蟑螂密度.方法 采用药激法调查列车蟑螂的种类和密度;采用烟熏、滞留喷洒、毒饵、胶饵和超低容量喷雾等方法,进行蜂螂防治效果的研究.结果 德国小蠊在武汉列车蟑螂种群构成比为91.60%~94.46% ;高等级列车至低等级列车的蟑螂侵害率依次上升为6.85%~37.69%;单纯滞留喷洒和烟熏灭蟑1周后的杀灭效果为82.35%~100%,但是2个月左右蟑螂密度迅速回升;定期采用滞留喷洒加灭蟑胶饵和毒饵法灭蟑1周后的杀灭效果为91.94%~100%,2个月后蟑螂密度持续维持较低水平;用超低容量喷雾法和烟熏法应急处理车厢的48 h杀灭率分别为95

  5. Branch-based model for the diameters of the pulmonary airways: accounting for departures from self-consistency and registration errors.

    Science.gov (United States)

    Neradilek, Moni B; Polissar, Nayak L; Einstein, Daniel R; Glenny, Robb W; Minard, Kevin R; Carson, James P; Jiao, Xiangmin; Jacob, Richard E; Cox, Timothy C; Postlethwait, Edward M; Corley, Richard A

    2012-06-01

    We examine a previously published branch-based approach for modeling airway diameters that is predicated on the assumption of self-consistency across all levels of the tree. We mathematically formulate this assumption, propose a method to test it and develop a more general model to be used when the assumption is violated. We discuss the effect of measurement error on the estimated models and propose methods that take account of error. The methods are illustrated on data from MRI and CT images of silicone casts of two rats, two normal monkeys, and one ozone-exposed monkey. Our results showed substantial departures from self-consistency in all five subjects. When departures from self-consistency exist, we do not recommend using the self-consistency model, even as an approximation, as we have shown that it may likely lead to an incorrect representation of the diameter geometry. The new variance model can be used instead. Measurement error has an important impact on the estimated morphometry models and needs to be addressed in the analysis.

  6. Branch-Based Model for the Diameters of the Pulmonary Airways: Accounting for Departures From Self-Consistency and Registration Errors

    Energy Technology Data Exchange (ETDEWEB)

    Neradilek, Moni B.; Polissar, Nayak L.; Einstein, Daniel R.; Glenny, Robb W.; Minard, Kevin R.; Carson, James P.; Jiao, Xiangmin; Jacob, Richard E.; Cox, Timothy C.; Postlethwait, Edward M.; Corley, Richard A.

    2012-04-24

    We examine a previously published branch-based approach to modeling airway diameters that is predicated on the assumption of self-consistency across all levels of the tree. We mathematically formulate this assumption, propose a method to test it and develop a more general model to be used when the assumption is violated. We discuss the effect of measurement error on the estimated models and propose methods that account for it. The methods are illustrated on data from MRI and CT images of silicone casts of two rats, two normal monkeys and one ozone-exposed monkey. Our results showed substantial departures from self-consistency in all five subjects. When departures from selfconsistency exist we do not recommend using the self-consistency model, even as an approximation, as we have shown that it may likely lead to an incorrect representation of the diameter geometry. Measurement error has an important impact on the estimated morphometry models and needs to be accounted for in the analysis.

  7. Clinical application of implantation of blue light-filtering aspheric intraocular lens by micro incision%微切口预装式蓝光滤过非球面人工晶状体临床应用

    Institute of Scientific and Technical Information of China (English)

    刘汝瑜; 宋慧; 汤欣; 魏荫娟

    2015-01-01

    Objective To compare the surgically induced astigmatism (SIA) of 2.0mm coaxial microincision cataract surgery (MICS) with 3.0mm small-incision cataract surgery (SICS) with blue light-filtering aspheric intraocular lens (IOL) implantation.Methods Retrospective case series of 48 cataract eyes undertaken phacoemulsification and IOL implantation from October 2012 to January 2013.MICS:26 eyes with 1-piece blue light-filtering aspheric intraocular lens by micro incision (iSert1,HOYA);SICS:22 eyes with 3-piece blue light-filtering aspheric intraocular lens by small incision (PY60AD,HOYA).Anterior chamber depth after mydriasis,corneal astigmatism,tilt and deviation of IOLs were measured using Scheimpflug system (Pentacam,Oculus) and analyzed with Image-pro plus 6.0 software.Slit lamp anterior segment photography and photoshop7.0 analyzed IOL rotation.Follow up was I week and 1 month.Results A significant SIA difference was found 1 week after surgery (P <0.05),no significant difference was found 1 month after surgery (P >0.05).With dilated pupil,there was a significant difference a month after surgery (P <0.05).No significant difference was found 1 week after surgery (P >0.05).Deviation,tilt and rotation of IOLs between the two groups showed no statistical significance (P >0.05).Conclusions Preloaded blue light-filtering aspheric intraocular lens by micro incision causes smaller SIA,is favor for visual recovery in short-term postoeration.%目的 观察2.0 mm同轴微切口白内障超声乳化(microincision cataract surgery,MICS)吸除术后植入微切口预装式蓝光滤过非球面人工晶状体(IOL)的手术源性散光(surgically induced astigmatism,SIA)及囊袋内稳定性,并与传统3.0 mm小切口白内障超声乳化(small-incision cataract surgery,SICS)手术进行比较.方法 回顾性系列病例研究.回顾性分析天津市眼科医院白内障中心于2012年10月至2013年1月白内障患者48只眼行超声乳化白

  8. Relationship between water departure and capacity loss of α and β-PbO 2 using an all solid-state system: Estimation of proton diffusion coefficient

    Science.gov (United States)

    Zerroual, L.; Fitas, R.; Djellouli, B.; Chelali, N.

    The proton diffusion coefficient for both fresh and heat-treated (140 and 230 °C, respectively) α and β-PbO 2 electrodes was estimated at room temperature using Galvanostatic Intermittent Titration Technique (GITT). PbO 2 samples were prepared by electroformation of cured plates. HSbO 3· xH 2O with a conductivity of 3.29 × 10 -3 Ω -1 cm -1, was used as solid protonic conductor (SPC) electrolyte. It was found that when structural water is removed, the capacity of both α and β-PbO 2 electrodes decreases and the ohmic drop increases. The departure of structural water affects considerably the value of proton diffusion coefficient.

  9. Relationship between water departure and capacity loss of {alpha} and {beta}-PbO{sub 2} using an all solid-state system: Estimation of proton diffusion coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Zerroual, L.; Fitas, R.; Djellouli, B.; Chelali, N. [Laboratoire d' Energetique et Electrochimie du Solide, Universite Ferhat ABBAS, Setif 19000 (Algeria)

    2006-08-25

    The proton diffusion coefficient for both fresh and heat-treated (140 and 230{sup o}C, respectively) {alpha} and {beta}-PbO{sub 2} electrodes was estimated at room temperature using Galvanostatic Intermittent Titration Technique (GITT). PbO{sub 2} samples were prepared by electroformation of cured plates. HSbO{sub 3}.xH{sub 2}O with a conductivity of 3.29x10{sup -3}{omega}{sup -1}cm{sup -1}, was used as solid protonic conductor (SPC) electrolyte. It was found that when structural water is removed, the capacity of both {alpha} and {beta}-PbO{sub 2} electrodes decreases and the ohmic drop increases. The departure of structural water affects considerably the value of proton diffusion coefficient. (author)

  10. What if It Was Like a Departure Lounge at an Airport? - eHealth for Healthcare Staff in a Swedish Healthcare Organization, a Participatory Design Study.

    Science.gov (United States)

    Nilsson, Lina; Hofflander, Malin

    2016-01-01

    eHealth is implemented in everyday work practice as a tool to improve accessibility and patient participation as well as healthcare efficiency. The aim of this study was to explore healthcare staff's experiences and ideas about how eHealth ought to be designed to be a useful tool in everyday work practice in a Swedish healthcare organization. Healthcare staff (n=7) at the micro level in a Swedish healthcare organization, participated in four Participatory Design workshops about eHealth design. eHealth could be a more useful and efficient tool in everyday work practice if it were designed more purposefully for its local setting and intended users, like the information system in 'a departure lounge of an airport'. Including healthcare staff in design discussions concerning eHealth tools for everyday work practice may improve the efficiency of eHealth as an everyday tool and support for healthcare staff.

  11. 角膜表面非球面形态数字表达研究的沿革%The development of the study on the expression of corneal asphericity

    Institute of Scientific and Technical Information of China (English)

    施明光; 王若洁

    2013-01-01

    Corneal asphericity has been a topic in clinical ophthalmology.This article discusses a corneal surface model based on corneal topography height data,as well as the Q value calculated by tangential data and axial data.The method of using the tangential data,which can be used to calculate the Q-values of all the semi-meridians by coordinate circumrotation,solved the problem of the accuracy and positioning of calculated Q-value.Related firdings support the accuracy and stability of this method.%角膜表面的非球面形态特性一直是眼科临床上一个受关注的课题.笔者阐述和讨论了用角膜地形图仪高度图数据建立角膜表面的模型技术,以及用角膜曲率半径值包括角膜地形图轴向图与正切图数据来计算角膜表面的Q值技术.提出应用角膜地形图正切图数据进行偏微分和拟合处理,计算半子午线截痕的Q值,以及采用坐标旋转技术计算出所有半子午线Q值的技术,解决了Q值计算的精确性和定位性问题.所有应用该技术的报道都表明样本研究的结果具有理想的精确性和稳定性.

  12. SMILE术后角膜前表面非球面性与角膜高阶像差的关系%The correlation between corneal asphericity and higher order aberrations after SMILE surgery

    Institute of Scientific and Technical Information of China (English)

    苏小连; 王雁

    2014-01-01

    Objective To evaluate the characteristics of anterior corneal asphericity and higher order aberrations after SMILE surgery,and to analyze the correlation between them.Methods In this prospective study,41 subjects who underwent SMILE surgery were enrolled with right eyes selected for the study.The asphericity coefficient Q-value at diameters of 6,7,8 and 9 mm and total higher order aberrations (HOA),spherical aberrations (Z40),secondary spherical aberrations (Z60),vertical coma (Z3-1),horizontal coma (Z31),y-trefoil (Z3-3) and x-trefoil (Z33) of the cornea were measured before surgery and 3 months following the surgery.A paired-samples t test and Pearson correlation were used for analysis.Results All Q-values increased from negative to positive after SMILE surgery and the differences were statistically significant (t=-23.558,-26.661,-28.366,-28.788,P<0.01).Corneal HOA,Z40,Z60,Z3-1 and Z31 increased and the differences were statistically significant as well (t=-11.815,-11.813,-16.209,6.470,4.835,P<0.01).However,the change in Z3-3 or Z33 was not significant (t=0.278,-1.064,P>0.05).Among corneal higher order aberrations,a linear correlation was found between the Q-value and corneal HOA,Z40 and Z3-t before surgery (P<0.05).The change in corneal HOA and Z40 had a positive linear correlation with the Q-value at each diameter (HOA:r=0.554,0.480,0.416,0.352,P<0.05; Z40:r=0.671,0.577,0.495,0.395,P<0.05).The difference in Z3-1 had a positive linear correlation with the Q-values at diameters 6 and 7 mm (r=0.377,0.342,P<0.05).The difference in Z31 had a positive linear correlation with the Q-values at diameters 6,7 and 8 mm (r=0.436,0.385,0.316,P<0.05).No linear correlation was found between the changes in the Q-values at each diameter and those of Z3 3,Z33 or Z60 (P>0.05).There was not a linear correlation between the change in the Q-values and lens diameter (P>0.05).Lens diameter had a negative linear correlation with the changes in HOA and Z40 (r=-0

  13. Q值调整个体化准分子激光原位角膜磨镶术术后角膜非球面变化%Q-Factor Customized Aspheric Ablation Profile after LASIK for Myopia

    Institute of Scientific and Technical Information of China (English)

    姚春艳; 翟芳; 刘超; 郑玲; 孙守彬; 温泉; 孙伟英; 盛毅; 朱佳

    2012-01-01

    目的:观察Q值调整非球面切削与标准化LASIK术后不同角膜直径下的角膜的非球面变化来分析Q值引导个性化切削技术的临床效果.方法:前瞻性研究.随机选取2010年至2011年来我院就诊的准分子手术患者35例68眼,分别进行标准化LASIK(S组:17例34眼)和Q值调整个体化LASIK(Q组:18例34眼)矫治.术前2组各项指标均相似,差异无统计学意义.术前屈光度数分别为标准组球镜平均值为-4.76±2.02D(-1.5D~-9.75D),柱镜平均值为-0.71± 0.7D(0~-2.5D)和Q值个体化组球镜平均值为-4.78±2.21D(-1.5~-9.5D),柱镜平均值为-0.84±0.55D(0~-2.5D)两组,对比两组非球面切削与标准化LASIK术后1个月不同角膜直径下的Q值及△Q.结果:两组术前Q10、Q15、Q20、Q25、Q30平均值分别为标准组:-0.12、-0.17、-0.20、-0.25、-0.30,Q值个体化组:-0.14、-0.19、-0.22、-0.27、-0.32..术后一个月两组的△Q(△Q=Qpost - Qpre)△Q10、△Q15、△Q20△Q25、△Q30分别为标准组:0.58、0.88、1.08、1.10、0.85,Q值个体化组,0.39、0.75、1.03、1.10、0.84.△Q10和△Q15术前术后变化在角膜直径为3.5mm之内时的差异有统计学意义.结论:Q值调整的个体化准分子激光原位角膜磨镶术术后角膜非球面变化与标准组相比皆由术前的长椭圆型Q值向扁椭圆型变化,但Q值调整的个体化组在角膜中央区的扁椭圆变化小于标准组,尤其在角膜中央3.5mm.说明Q值调整的个体化LASIK组在角膜中央区比标准组具有优势.%Objective: To compare the results of the Q-factor customized aspheric ablation profile with Standard ablation pattern for the correction of myopia and myopic astigmatism. Methods: Perspective research. Thirty-five patients, sixty-eight eyes were enrolled in a controlled study in which the eighteen patients thirty-four eyes were treated with the Q-factor customized profile (custom-Q group) and the seventeen patients thirty-four eyes were treated with

  14. Effect of tilt and decentration of intraocular lens asphericity on visual quality%不同人工晶状体植入术后倾斜和偏心及视觉质量的临床研究

    Institute of Scientific and Technical Information of China (English)

    王莹; 马忠旭; 刘汝瑜; 张伟

    2011-01-01

    Objective: To analyze the effect of tilt and decentration of intraocular lenses (IOLs) asphericity on visual quality after pha-coemulsification surgery and IOLs implantation. Methods: It was a prospective clinical study. A total of 85 eyes of 69 patients with IOLs implantation and 3 to 4 months after surgery were analyzed in this study, including 30 eyes with spherical IOL of Sensar AR40e, 25 eyes with aspherically neutral IOL of Softec HD and 30 eyes aspheric IOL of Tecnis ZA9003 with negative spherical aberration. At postoperat ive follow-up visits, higher-order aberrations (HOAs) and modulation transfer function(MTF) at six spatial frequencies (5,10,15,20,25,30cpd) were measured in 5.0 mm pupil size. Tilt and decentration of the IOLs were measured using Scheimpflug photography(Pentacam ,0culus). The tilt and decentration, HOAs and subtracted lower order aberration MTF( MTF(HOA) )were compared. The effect of tilt and decentration on HOAs and MTF(HOA)was assessed using multiple regression analysis. Results: No significant differences in IOL tilt or decentration were found(F=0.001, F=0.050;P=0.999, ,P=0.952).The spherical aberration in AR40e group was largest and the differences were statistically significant(F= 65.68, P=0.000). In 5.0 mm pupil size,MTF(HOA)at all spatial frequencies in AR40e group were lowest and the differ ences were statistically significant(P<0.05). Tilt and decentration did not significantly affect HOAs and MTF(HOA)- Conclusion: The amounts of tilt and decentration of both IOLs are not large enough to affect the correction of spherical aberration and cause deterioration of visual quality.%目的:研究白内障超声乳化吸除术植入不同球差人工晶状体(IOL)的倾斜和偏心对高阶像差(HOAs)和调制传递函数(MTF)的影响.方法:前瞻性研究.选取老年性白内障患者69例(85只眼),随机分成3组,25例(30只眼)植入球面IOL Sensar AR40e,19例(25只眼)植入零球差IOL Softec HD,30

  15. Using ToxCast data to reconstruct dynamic cell state trajectories and estimate toxicological points of departure.

    Data.gov (United States)

    U.S. Environmental Protection Agency — Background: High-content imaging (HCI) allows simultaneous measurement of multiple cellular phenotypic changes and is an important tool for evaluating the biological...

  16. Comparison between OPD-scan results and contrast sensitivity of three intraocular lenses: spheric AcrySof SN60AT, aspheric AcrySof SN60WF and multifocal AcrySof Restor lens Estudo comparativo da análise de frente de onda e sensibilidade ao contraste entre as lentes intra-oculares multifocal AcrySof Restor SN60D3, monofocal AcrySof SN60WF asférica e a monofocal SN60AT esférica

    Directory of Open Access Journals (Sweden)

    Celso Takashi Nakano

    2009-08-01

    Full Text Available Purpose: Compare the OPD-scan results and the contrast sensitivity in patients who had implantation of the AcrySof SN60D3 multifocal IOL, the AcrySof SA60AT spheric monofocal IOL and the AcrySof SN60AT aspheric monofocal IOL. Methods: Thirty-two eyes received the multifocal IOL, 32 eyes received the spheric monofocal IOL and 32 eyes received the aspheric monofocal IOL. They were closely paired in age, sex, pre-operative wavefront analysis and contrast sensitivity. All patients was tested with the OPD-scan aberrometer, ETDRS chart at 100% and 9% contrasts and contrast sensitivity. Results: Statistically significant differences were detected more total aberration in SN60AT group (KW = 9.42; p=0.009 when compared to SN60D3 group (p=0.016 and SN60WF group (p=0.0047. The SN60AT group (KW = 16.20; p=0.0003 showed with high spherical aberration values compared to the SN60WF (p=0.00046 and SN60D3 (p=0.0014 group. No significant differences were found between groups in far-distance VA measured using ETDRS at 100% and 9% contrast. The SN60D3 group compared to SN60AT group (p=0.016 had low contrast sensitivity (log units with statistical difference in 6.0 cpd (KW = 7.84; p=0.0199, but no statistical difference between SN60WF and SN60AT group (p=0.91 and SN60WF and SN60D3 group (p=0.051. The SN60D3 group had low contrast sensitivity performed under mesopic conditions (KW = 10.79; p=0,0045 in 6cpd spatial frequency compared to the SN60AT group (p=0.011 and to the SN60WF group (p=0.007 with statistical significant differences. Conclusion: In all analyzed parameters of OPD-scan aberrometry the aspheric and the multifocal IOLs provided less total and spherical aberrations than spheric IOLs. All IOLs provided an excellent high and low contrasts vision, the multifocal IOL was as good as the spheric and aspheric monofocal IOLs.Objetivo: Comparar a sensibilidade ao contraste e análise de "wavefront" com OPD-scan em pacientes submetidos a cirurgia de facoemulsifica

  17. Replicated high-density genetic maps of two great tit populations reveal fine-scale genomic departures from sex-equal recombination rates

    NARCIS (Netherlands)

    Van Oers, K.; Santure, A.W.; de Cauwer, I.; Van Bers, N.E.M.; Crooijmans, R.P.M.A.; Sheldon, B.C.; Visser, M.E.; Slate, J.; Groenen, M.A.M.

    2014-01-01

    Linking variation in quantitative traits to variation in the genome is an important, but challenging task in the study of life-history evolution. Linkage maps provide a valuable tool for the unravelling of such trait−gene associations. Moreover, they give insight into recombination landscapes and be

  18. Surface Figure Metrology for CELT Primary Mirror Segments

    Energy Technology Data Exchange (ETDEWEB)

    Sommargren, G; Phillion, D; Seppala, L; Lerner, S

    2001-02-27

    The University of California and California Institute of Technology are currently studying the feasibility of building a 30-m segmented ground based optical telescope called the California Extremely Large Telescope (CELT). The early ideas for this telescope were first described by Nelson and Mast and more recently refined by Nelson. In parallel, concepts for the fabrication of the primary segments were proposed by Mast, Nelson and Sommargren where high risk technologies were identified. One of these was the surface figure metrology needed for fabricating the aspheric mirror segments. This report addresses the advanced interferometry that will be needed to achieve 15nm rms accuracy for mirror segments with aspheric departures as large as 35mm peak-to-valley. For reasons of cost, size, measurement consistency and ease of operation we believe it is desirable to have a single interferometer that can be universally applied to each and every mirror segment. Such an instrument is described in this report.

  19. A procedure for estimating the electron temperature and the departure of the LTE condition in a time-dependent, spatially homogeneous, optically thin plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bredice, F. [Centro de Investigaciones Opticas, La Plata (Argentina); Borges, F.O., E-mail: borges@if.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Fisica. Lab. de Plasma e Espectroscopia; Di Rocco, H.O. [Instituto de Fisica Arroyo Seco (IFAS), Universidad Nacional del Centro, Tandil (Argentina); Mercado, R.S. [Grupo de Espectroscopia Optica de Emision y Laser (GEOEL), Universidad del Atlantico, Barranquilla (Colombia); Villagran-Muniz, M. [Laboratorio de Fotofisica, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico (Mexico); Palleschi, V. [Applied Laser Spectroscopy Laboratory, ICCOM-CNR, Pisa (Italy)

    2013-08-15

    We present a method to estimate the temperature of transient plasmas and their degree of departure from local thermodynamic equilibrium conditions. Our method is based on application of the Saha–Boltzmann equations on the temporal variation of the intensity of the spectral lines of the plasma, under the assumption that the plasmas at the different times when the spectra were obtained are in local thermodynamic equilibrium. The method requires no knowledge of the spectral efficiency of the spectrometer/detector, transition probabilities of the considered lines, or degeneracies of the upper and lower levels. Provided that the conditions of optically thin, homogeneous plasma in local thermodynamic equilibrium are satisfied, the accuracy of the procedure is limited only by the precision with which the line intensities and densities can be determined at two different temperatures. The procedure generates an equation describing the temporal evolution of the electron number density of transient plasmas under local thermodynamic equilibrium conditions. The method is applied to the analysis of two laser-induced breakdown spectra of cadmium at different temperatures. (author)

  20. Analysis of Void Fraction Distribution and Departure from Nucleate Boiling in Single Subchannel and Bundle Geometries Using Subchannel, System, and Computational Fluid Dynamics Codes

    Directory of Open Access Journals (Sweden)

    Taewan Kim

    2012-01-01

    Full Text Available In order to assess the accuracy and validity of subchannel, system, and computational fluid dynamics codes, the Paul Scherrer Institut has participated in the OECD/NRC PSBT benchmark with the thermal-hydraulic system code TRACE5.0 developed by US NRC, the subchannel code FLICA4 developed by CEA, and the computational fluid dynamic code STAR-CD developed by CD-adapco. The PSBT benchmark consists of a series of void distribution exercises and departure from nucleate boiling exercises. The results reveal that the prediction by the subchannel code FLICA4 agrees with the experimental data reasonably well in both steady-state and transient conditions. The analyses of single-subchannel experiments by means of the computational fluid dynamic code STAR-CD with the CD-adapco boiling model indicate that the prediction of the void fraction has no significant discrepancy from the experiments. The analyses with TRACE point out the necessity to perform additional assessment of the subcooled boiling model and bulk condensation model of TRACE.

  1. Stress evolution following the 1999 Chi-Chi, Taiwan, earthquake: Consequences for afterslip, relaxation, aftershocks and departures from Omori decay

    Science.gov (United States)

    Chan, C.-H.; Stein, R.S.

    2009-01-01

    We explore how Coulomb stress transfer and viscoelastic relaxation control afterslip and aftershocks in a continental thrust fault system. The 1999 September 21 Mw = 7.6 Chi-Chi shock is typical of continental ramp-d??collement systems throughout the world, and so inferences drawn from this uniquely well-recorded event may be widely applicable. First, we find that the spatial and depth distribution of aftershocks and their focal mechanisms are consistent with the calculated Coulomb stress changes imparted by the coseismic rupture. Some 61 per cent of the M ??? 2 aftershocks and 83 per cent of the M ??? 4 aftershocks lie in regions for which the Coulomb stress increased by ???0.1 bars, and there is a 11-12 per cent gain in the percentage of aftershocks nodal planes on which the shear stress increased over the pre-Chi Chi control period. Second, we find that afterslip occurred where the calculated coseismic stress increased on the fault ramp and d??collement, subject to the condition that friction is high on the ramp and low on the d??collement. Third, viscoelastic relaxation is evident from the fit of the post-seismic GPS data on the footwall. Fourth, we find that the rate of seismicity began to increase during the post-seismic period in an annulus extending east of the main rupture. The spatial extent of the seismicity annulus resembles the calculated ???0.05-bar Coulomb stress increase caused by viscoelastic relaxation and afterslip, and we find a 9-12 per cent gain in the percentage of focal mechanisms with >0.01-bar shear stress increases imparted by the post-seismic afterslip and relaxation in comparison to the control period. Thus, we argue that post-seismic stress changes can for the first time be shown to alter the production of aftershocks, as judged by their rate, spatial distribution, and focal mechanisms. ?? Journal compilation ?? 2009 RAS.

  2. 两种不同攀设计非球面人工晶状体伪调节相关研究%Changes of pseudophakic accommodation of aspheric intraocular lens designs in phacoemulsification

    Institute of Scientific and Technical Information of China (English)

    赵玉琴; 李英俊; 金龙山

    2015-01-01

    Objective To compare the pseudophakic accommodation of different designs of aspheric intraocular lens (IOL) in phacoemulsification.Methods One hundred and twenty-six eyes with cataract surgery were randomized into 2 groups:an Acrysof IQ SN60WF (Alcon Laboratories,Fort Worth,Texas,USA) IOL group (59 eyes) and Akreos Adapt AO (Bausch & Lomb.,Rochester,NY,USA)IOL group (67 eyes).Patients were examined using anterior segment optical coherence tomography (AS-OCT),including anterior chamber depth (ACD),pupil diameter,and amplitude of pseudophakic accommodation,preoperatively and 6 months postoperatively.Results The IQ IOLs and AO IOLs group of mean pseudophakic accommodation was (1.26±0.34)D and (1.09±0.51)D,respectively,there was statistically significantly different (t =2.314,P =0.041).The mean pupil diameter measurements for IQ group and AO IOL group were (0.52±0.20)mm and (0.49±0.16)mm,respectively,which showed no statistically significant differences (t =0.946,P =0.541).The amplitude of pseudophakic accommodation was negative correlated with pupil diameter (r =-0.651,P =0.024).Conclusions The movement of aspheric IOLs in eyes after cataract surgery is an important mechanism for attaining good near vision without additional correction,2-point haptic design IOLs provide better pseudophakic accommodation than that of Four-point haptic designs.%目的 比较两种不同攀设计的非球面人工晶状体在囊袋内植入后伪调节力的差异.方法 临床病例对照研究.选择2012年5~12月在延边大学附属医院眼科行超声乳化白内障摘除联合人工晶状体植入术的老年性白内障患者82例(126只眼),应用随机数字表法髓机分为两组,SN60WF为IQ组植入“L”形Acrysof IQ SN60WF (Alcon Laboratories,Fort Worth,Texas,USA)人工晶状体(59只眼);Adapt AO为AO组植入一体四点Akreos Adapt AO (Bausch&Lomb,Rochester,NY,USA)人工晶状体(67只眼).采用眼前段光学相干断层扫描仪(AS-OCT)实时测量人工晶

  3. Effect of tilt and decentration of spherical and aspheric intraocular lens on visual quality%球面和非球面人工晶状体倾斜和偏心对视觉质量的影响

    Institute of Scientific and Technical Information of China (English)

    张伟; 马忠旭; 刘汝瑜; 张玲

    2010-01-01

    目的 研究超声乳化白内障吸除术后球面和非球面人工晶状体(intraocularlens,IOL)的倾斜和偏心及其对高阶像差(higher-order aberrations,HOAs)和视觉质量的影响.方法 前瞻性研究.取50例单纯性老年性白内障患者60只眼,30只眼随机植入AMO公司的球面IOLSensar AR40e,30只眼植入非球面IOLTecnisZA9003.术后3到4个月,检测患者在5.0mm瞳孔下的HOAs以及5、10、15、20、25、30周每度(cycles per degree,cpd)空间频率下的调制传递函数(modulation transfer function,MTF).通过Scheimpflug像,测量IOL的倾斜与偏心.比较两组间倾斜度和偏心值、HOAs及各空间频率下去除低阶像差的MTF(MTF(HOA))值.使用多元回归分析来确定倾斜和偏心对HOAs和视觉质量的影响.结果 光学部倾斜AR40e组(2.99±0.94)°,ZA9003组(2.98±1.15)°.光学部偏心AR40e组(0.30±0.13)mm,ZA9003组(0.31±0.14)mm.组间倾斜和偏心差异无统计学意义(Z=-0.044,-0.525,P=0.965,0.600,Mann-WhitneyU检验).总4阶球差,AR40e组(0.366±0.163)μm大于ZA9003组(0.027±0.072)μm,差异有统计学意义(t=-10.386,P=0.000).ZA9003组在5.0mm瞳孔直径下各频段的MTF(HOA)值均高于AR40e组,有统计学意义(P<0.05).两组IOL倾斜和偏心对各自的HOAs及各频段的MTF(HOA)值均无明显影响.结论 当IOL的倾斜和偏心在正常限度内时,不会危害非球面IOL对球差的补偿作用,不足以导致视觉质量的下降.%Objective To study tilt and decentration of spherical and aspheric IOL implantation after phacoemulsification surgery and effect on higher-order aberrations (HOAs) and visual quality. Methods It was a prospective clinical study. A total of 60 eyes (50 patients) were divided into 2 groups randomly, of 30 eyes in each group, one group with Sensar AR40e (AMO), one group with Tecnis ZA9003 (AMO). Three to four months after surgery, higher-order aberrations (HOAs) and modulation transfer function (MTF) at six spatial frequencies (5, 10, 15, 20

  4. The demand forecasting method selection of airport passenger departure checked baggage%机场离港旅客托运行李需求预测方法的选取

    Institute of Scientific and Technical Information of China (English)

    杨志超

    2014-01-01

    Through the analysis on the demand characteristics of airport passenger departure checked baggage, leading to checked baggage de-mand influence factors, selected the existing forecasting methods, selected the BP neural network model, analyzed its applicability, in order to accurately grasp the passengers departure checked baggage requirements, timely and effective allocation and scheduling related personnel and e-quipment.%通过分析机场离港旅客托运行李的需求特性,引出托运行李需求影响因素,对现有的预测方法进行筛选,选择了BP神经网络模型,并对其适用性进行了分析,以准确把握离港旅客的托运行李需求,及时有效地分配及调度相关人员与设备。

  5. Trapped ion imaging with a high numerical aperture spherical mirror

    Energy Technology Data Exchange (ETDEWEB)

    Shu, G; Dietrich, M R; Kurz, N; Blinov, B B, E-mail: shugang@u.washington.ed [Department of Physics, University of Washington, Seattle, WA 98105-1560 (United States)

    2009-08-14

    Efficient collection and analysis of trapped ion qubit fluorescence is essential for robust qubit state detection in trapped ion quantum computing schemes. We discuss simple techniques of improving photon collection efficiency using high numerical aperture (N.A.) reflective optics. To test these techniques we placed a spherical mirror with an effective N.A. of about 0.9 inside a vacuum chamber in the vicinity of a linear Paul trap. We demonstrate stable and reliable trapping of single barium ions, in excellent agreement with our simulations of the electric field in this setup. While a large N.A. spherical mirror introduces significant spherical aberration, the ion image quality can be greatly improved by a specially designed aspheric corrector lens located outside the vacuum system. Our simulations show that the spherical mirror/corrector design is an easy and cost-effective way to achieve high photon collection rates when compared to a more sophisticated parabolic mirror setup.

  6. Honour and departure Wim Klein

    CERN Multimedia

    Van Hove,L

    1976-01-01

    L.Van Hove rend hommage à Wim Klein qui a été découvert par le Prof.Bakker vers 1958 en Hollande où Wim Klein était artiste en divertissant le public par ses extraordinaires dons mathématiques.

  7. Aspherical photon and anti-photon surfaces

    Directory of Open Access Journals (Sweden)

    G.W. Gibbons

    2016-12-01

    Full Text Available In this note we identify photon surfaces and anti-photon surfaces in some physically interesting spacetimes, which are not spherically symmetric. All of our examples solve physically reasonable field equations, including for some cases the vacuum Einstein equations, albeit they are not asymptotically flat. Our examples include the vacuum C-metric, the Melvin solution of Einstein–Maxwell theory and generalisations including dilaton fields. The (anti-photon surfaces are not round spheres, and the lapse function is not always constant.

  8. Absolute Heterodyne Interferometer for Strongly Aspherical Mirrors

    NARCIS (Netherlands)

    Krieg, M.L.

    2004-01-01

    For the past thirty years, microchips have doubled in complexity every two years. This increasing complexity required that the size of the structures written on silicon halve at the same rate. A fundamentally limiting factor to the size of microchip structures is the wavelength of the lithographic p

  9. Absolute Heterodyne Interferometer for Strongly Aspherical Mirrors

    NARCIS (Netherlands)

    Krieg, M.L.

    2004-01-01

    For the past thirty years, microchips have doubled in complexity every two years. This increasing complexity required that the size of the structures written on silicon halve at the same rate. A fundamentally limiting factor to the size of microchip structures is the wavelength of the lithographic

  10. Migrating Broad-billed Sandpipers achieve high fuelling rates by taking a multi-course meal

    NARCIS (Netherlands)

    Verkuil, Y.I.; Dekinga, A; Koolhaas, A; van der Winden, J; van der Have, T M; Chernichko, I I

    2006-01-01

    In spring, large numbers of migrating Broad-billed Sandpipers make a stop-over in the Sivash, a shallow lagoon system in the Crimea, Ukraine, between the Black Sea and the Sea of Azov. Observed fuelling rates are high and, in just a few weeks, the birds can build up sufficient departure mass to reac

  11. Design of Object Lens for Helmet-Mounted Night Vision Goggles with High-Order Plastic Aspherical Surfaces%含高次塑料非球面的头盔微光夜视物镜设计

    Institute of Scientific and Technical Information of China (English)

    杨胜杰

    2009-01-01

    为使头盔微光夜视镜的重量更轻,同时保证其较好的成像性能,分析了光学塑料的特性及其加工,通过引入高次塑料非球面,设计了含有3个高次塑料非球面的6片式微光夜视物镜.该物镜具有大视场(40°、小F数(F/1.25)、小畸变(1%)的特点,光学传递函数在空间频率40lp/mm时,轴上传函≥0.6,轴外传函≥0.4,满足微光夜视物镜成像要求.相对具有同样性能的传统物镜系统,总长41 mm,为传统物镜的82.6%,重量13.3 g,仅为传统物镜的32.7%.为头盔式微光夜视系统减重设计提供了一个新的参考思路.

  12. Iterative surface construction for blind deflectometry

    Science.gov (United States)

    Zhao, Wenchuan; Graves, Logan R.; Huang, Run; Song, Weihong; Kim, DaeWook

    2016-09-01

    Freeform optics provide excellent performance for a wide variety of applications. However, obtaining an accurate freeform surface measurement is highly challenging due to its large aspheric/freeform departure. It has been proven that SCOTS (Software Configurable Optical Test System), an advanced deflectometry system developed at the University of Arizona, can measure the departure of a freeform surface from the desired shape with nanometer accuracy. Here, a new data processing technique was used to measure a freeform surface without any prior knowledge of the shape of the surface. Knowing only the geometry of one point on the test surface, this method can take a blind measurement of a freeform surface and arrive at the true surface through iterative construction.

  13. Earnings Management before CEO Departure: The Role of the Corporate Governance%高管离任前的盈余管理:公司治理机制能起到作用吗?

    Institute of Scientific and Technical Information of China (English)

    贺小刚; 张远飞; 连燕玲

    2012-01-01

    Executives will appear some abnormal behavior before their turnovers. For example in the state- owned enterprises, since the executives' remuneration is controlled by the government, they cannot get the satisfac- tory income in according to their efforts during their tenure. So that the executives who believe themselves should get much more returns may take risks when facing the end of tenure. A kind of "59-year-old" phenomenon appears in the state-owned firms, which means that executive inclines to take risk to invade and occupy other stakeholders' interest before he or she lose the management control. The topic of the executives' earning management behavior has attracted many scholars' attention; however they have not gotten by them is that managers have the dominant status about the the consistent conclusion. A basic conclusion made company business information, and their interests ( such as remuneration, career, etc. ) are closely related to the enterprises' operation performance, in order to max- imize their own revenue, the executives are more likely to make earnings management before departure in order to affect the shareholders' assessment on them( Pourciau, 1993; Dechow, et al, 1995 ). other studies show that execu- tives outgoing will not necessarily lead to take earnings management behavior (Murphy and Zimmerman, 1993 ), because of the unpredictability of unconventional changes to executives' jobs (Pourciau, 1993). In this paper, our key research question us that whether the CEO will have significant earnings management before departure, why some executives who left the company have serious earnings management while others rarely take earnings manage- ment? Exploring the root causes of this phenomenon is very important to understand the earnings management hap- pened in the firm. Based on the data of the listed companies in China from 2003 to 2009, in the overall sample, the level of earn- ings management between the one year before the CEO departure and

  14. On Dynamic Risk Pre-warning Method & Its Application in Shield Departure & Reception Construction Procedures%盾构进出洞施工动态风险预警方法与应用

    Institute of Scientific and Technical Information of China (English)

    汤漩

    2013-01-01

      In the process of shield-tunnel construction, risk research & monitoring on shield departure & reception can decrease accidences and damages effectively. According to risk identification, risk factors evaluation, risk monitoring indexes and the confirmation of grading reference range, a pre-warning method of shied departure & reception is formed on the basis of dynamic risk monitoring indexes. Practice in projects shows that this kind of dynamic risk pre-warning method can detect risk condition in time during construction, provide good conditions for risk prevention and emergency response and obtain great application effects finally.%  在盾构法隧道施工工程中,对盾构进出洞施工风险进行研究和监控,能有效地减少工程事故损失。通过盾构进出洞施工风险辨识、风险因素评价和监控指标项及其分级基准范围的确定,形成了一种基于监控指标动态监控的盾构进出洞施工风险预警方法,在工程应用中能及时监控风险情况,为风险防范和应急处理创造良好条件,取得较好的应用效果。

  15. Stochastic Dynamic User Optimum Model with Departure Time Choice Based on Cumulative Prospect Theory%基于累积前景理论的出发时间选择SDUO模型

    Institute of Scientific and Technical Information of China (English)

    张波; 隽志才; 林徐勋

    2013-01-01

    The existing dynamic traffic assignment models that deal with departure time choice generally construct utility or disutility functions based on the concepts of time-window and schedule delay. Travelers are assumed to be entirely rational and have full access to the information of dynamic traffic system. The reference points and the difference between arrival times within time-window are not considered in our assumption. There are often systematical deviations between traffic assignment results and real traffic (low. Traffic system is an uncertain dynamic system characterized as time-varying and stochastic. Constrained by the compound effect of imperfect traffic information, limited cognitive capability, value orientations and the degree of rationality, travelers are rarely able to perform their travel decisions with entire rationality. Researches of psychology and behavior science demonstrate that decisions under uncertainty appear to be bounded rational. As a descriptive theory, the Prospect Theory reveals psychological and behavioral mechanisms of people with bounded rationality, and demonstrates the patterns and human decision-making characteristics under risk. A few empirical studies experimenting on travelers have shown that travel behaviors under uncertainty, especially in the choices of departure time and route, and their attitude towards risk coincide with the main assumptions of Prospect Theory. Focused oncommuting trips during peak hours in the morning, this paper explores the usefulness of Prospect Theory in the dynamic traffic assignment. First, commuters are classified into early arrivals and late arrivals according to when they arrive at their workplace. The reference points for departure time and route choices are defined in a dynamic stochastic traffic network. The continuous functions of Prospect Theory for departure time and route choices in the condition of continuous traffic flow are constructed. A Stochastic Dynamic User Optimum (SDUO) model

  16. 非球面人工晶状体度数计算的最优化%Preliminary evaluation of an algorithm to minimize the power error selection of an aspheric intraocular lens by optimizing the estimation of the corneal power and the effective lens position

    Institute of Scientific and Technical Information of China (English)

    DavidP Piero; VicenteJ Camps; MaraL Ramn; VernicaMateo; Roberto Soto-Negro

    2016-01-01

    目的::通过评价非球面人工晶状体( intraocular lens, IOL)屈光度的可预测性,初步开发一种计算屈光度( PIOL )的优化算法。方法:本研究纳入植入非球面 IOL ( LENTIS L-313, Oculentis GmbH)65眼,并分为2组:A组8例12眼,PIOL≥23.0D;B组35例53眼,PIOL<23.0D。术后3mo进行屈光度可预测性评价。参考角膜屈光力估计所致的可变性屈光指数计算出校正的IOL度数( PIOLadj )及屈光结果,根据年龄和解剖学因素得出校正的有效晶状体位置( adjusted effective lens position, ELPadj )。结果:术后A、B两组等效球镜度数分别为-0.75~+0.75 D、-1.38~+0.75D。 A、B两组的PIOLadj和实际晶状体屈光度(PIOLReal)之间无统计学差异(P=0.64、0.82)。 Bland-Altman分析显示A、B两组PIOLadj和PIOLReal之间的一致性区间分别为+1.11~-0.96 D和+1.14~-1.18 D。 Hoffer Q公式和Holladay I公式计算PIOLadj和PIOL之间存在临床和统计学上的显著差异(P<0.01)。结论:植入非球面IOL白内障手术的屈光可预测性可通过平行轴光学联合线性法则使角膜屈光力及晶状体位置相关误差最小化。%•AIM: To evaluate the refractive predictability achieved with an aspheric intraocular lens ( IOL ) and to develop a preliminary optimized algorithm for the calculation of its power ( PIOL ) .•METHODS:This study included 65 eyes implanted with the aspheric IOL LENTIS L-313 ( Oculentis GmbH ) that were divided into 2 groups:12 eyes (8 patients) with PIOL≥23. 0 D (group A), and 53 eyes (35 patients) with PIOL<23. 0 D ( group B ). The refractive predictability was evaluated at 3mo postoperatively. An adjusted IOL power ( PIOLadj ) was calculated considering a variable refractive index for corneal power estimation, the refractive outcome obtained, and an adjusted effective lens position ( ELPadj ) according to age and anatomical factors.•RESULTS: Postoperative spherical equivalent ranged from -0. 75 to +0. 75 D and from -1

  17. Evaluation of visual acuity under different contrasts and luminances in eyes implanted with aspheric multifocal intraocular lenses%非球面多焦点人工晶状体植入眼不同背景亮度及不同对比度视功能观察

    Institute of Scientific and Technical Information of China (English)

    赵银莹; 李军花; 常平骏; 赵云娥

    2010-01-01

    目的 分析非球面多焦点人工晶状体(MIOL)[ReSTOR MIOL(SN6AD3)]植入眼在不同背景亮度不同对比度下的视功能.方法 采用前瞻性研究.2009年2月至2009年7月行白内障超声乳化吸除并植入SN6AD3且随访资料完整的病例26例(42眼),术后6个月在最佳远矫正状态下,采用多功能电子视力测量仪(MFVA-100)测试不同背景亮度(250、85、25 cd/m2)下不同对比度(100%、25%、10%、5%)视标的LogMAR视力.采用Dunnett's T3多重比较法对所得视力进行统计分析.结果 在250 cd/m2背景亮度下,不同对比度(100%、25%、10%、5%)视力平均值分别为0.01、0.23、0.40、0.62;85 cd/m2背景亮度下为0.02、0.26、0.46、0.74;25 cd/m2背景亮度下为0.08、0.32、0.49、0.63;在这3种背景亮度下,视力随着对比度下降而下降,差异有统计学意义(P均<0.05).同一对比度视标,不同背景亮度(250、85、25 cd/m2)下的视力采用Dunnett's T3多重比较法分析,结果示差异无统计学意义(P均>0.05).结论 植入非球面ReSTOR MIOL(SN6AD3)患者无论在高亮(250 cd/m2)、标准(85 cd/m2)、中间(25 cd/m2)背景亮度下均可获得满意的视力.视标的对比度对视力的影响较背景亮度更大.%Objective To evaluate the differences in contrast visual acuity (VA) under different background illuminations in patients who had been implanted with the ReSTOR aspheric multifocal intraocular lens (MIOL)(SN6AD3). Methods This was a prospective study. Forty-two eyes of 26 patients who had received ReSTOR MIOL (SN6AD3) implantation after cataract extraction were enrolled. Six months postoperatively, best corrected distance VA was measured at 4 contrast levels (100%, 25%, 10%, 5%) under 3 background illumination levels (250 cd/m2, 85 cd/m2, 25 cd/m2)using a multi-functional visual acuity tester (MFVA-100). Dunnett's T3 multiple comparison was used for statistical anaylysis. Results The mean VA at the 4 contrast levels (100%, 25%, 10%, 5%)under 250 cd

  18. Core surface flow modelling from high-resolution secular variation

    DEFF Research Database (Denmark)

    Holme, R.; Olsen, Nils

    2006-01-01

    -flux hypothesis, but the spectrum of the SV implies that a conclusive test of frozen-flux is not possible. We parametrize the effects of diffusion as an expected misfit in the flow prediction due to departure from the frozen-flux hypothesis; at low spherical harmonic degrees, this contribution dominates...... the expected departure of the SV predictions from flow to the observed SV, while at high degrees the SV model uncertainty is dominant. We construct fine-scale core surface flows to model the SV. Flow non-uniqueness is a serious problem because the flows are sufficiently small scale to allow flow around non......-series of magnetic data and better parametrization of the external magnetic field....

  19. High-frequency Born synthetic seismograms based on coupled normal modes

    Science.gov (United States)

    Pollitz, Fred F.

    2011-01-01

    High-frequency and full waveform synthetic seismograms on a 3-D laterally heterogeneous earth model are simulated using the theory of coupled normal modes. The set of coupled integral equations that describe the 3-D response are simplified into a set of uncoupled integral equations by using the Born approximation to calculate scattered wavefields and the pure-path approximation to modulate the phase of incident and scattered wavefields. This depends upon a decomposition of the aspherical structure into smooth and rough components. The uncoupled integral equations are discretized and solved in the frequency domain, and time domain results are obtained by inverse Fourier transform. Examples show the utility of the normal mode approach to synthesize the seismic wavefields resulting from interaction with a combination of rough and smooth structural heterogeneities. This approach is applied to an ∼4 Hz shallow crustal wave propagation around the site of the San Andreas Fault Observatory at Depth (SAFOD).

  20. Calculation of Departure from Nucleate Boiling Ratio (DNBR) minimum for accident analysis of main steam line break at Angra-1; Calculo do minimo DNBR para analise do acidente de ruptura da linha principal de vapor em Angra-1

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Marcio Dornellas [ELETROBRAS Termonuclear S.A. (ELETRONUCLEAR), Rio de Janeiro, RJ (Brazil). E-mail: mdorne@eletronuclear.gov.br

    2000-07-01

    The maintenance costs, the operational problems and the failures possibilities of the boron injection system, composed by pumps, valves, heated lines and the boron injection tank, make this tank removal or the boron concentration reduction advisable for Angra 1 Power Plant. The main accident from chapter XV of the final safety analysis report affected by this modification is the main steam line break. It is necessary the interaction of the areas of Accidents and Transients Analysis (RETRAN 02/Mod 5.1 code), Neutronics (APA System) and Thermohydraulics (COBRA IIIC/MIT) to analyse this accident. The present Angra 1 boron concentration is 20000 ppm and it could be reduced to 2000 ppm as a result of the present study. The Departure from Nucleate Boiling Ratio (DNBR) is the restrictive parameter of this accident, which is calculated from the initials and boundary conditions obtained from the Transients and Accidents Analysis and Neutronics areas. (author)

  1. ATIS 条件下出发时间选择对交通影响的仿真研究∗%Simulation of the Impact of Departure Time Choice Behavior on Traffic Operation under ATIS

    Institute of Scientific and Technical Information of China (English)

    李春燕; 叶晓飞; 陈峻; 孙正安

    2016-01-01

    为研究实时信息条件下驾驶人的不同出发时间选择行为对城市交通运行的影响,以描述型、定量型、预测型和指示型4种实时信息条件下驾驶人的出发时间选择行为为研究对象,采用 Vissim微观仿真法,对不同出发时间选择行为造成的交通拥堵改善情况进行分析。通过试凑法将交通流量输入实际道路网,实现调查方案中交通运行实时信息内容的定量化表达;通过模拟无信息和4种实时信息条件下驾驶人的不同出发时间选择行为,对比分析道路交通延误,判断交通运行情况。以南京市驾驶人出发时间选择行为为例进行仿真分析,结果表明提供实时信息条件下道路交通延误周期段数减少33%,交通延误时间段明显得以分散,Vissim 仿真能够很好地模拟微观出行行为带来的宏观交通影响。%To study the impacts of choice behavior of departure time on urban traffic operation under real-time pro-vision of traveler information through advanced traveler information systems (ATIS),taking drivers′choice behavior of different departure time as the target under 4 scenarios with different types of real-time information,which is descriptive, quantitative,forecasted and instructional information respectively.Vissim software is used to simulate and analyze the im-provement of traffic operation due to the choice behavior of different departure time.Using the trial and error method, traffic volume is used as an input to the simulation,in orderto ensure that the impact of different provision of real-time in-formation can be quantitatively expressed in the simulation experiments.By simulating choice behavior of different depar-ture time under the scenario without any real-time information and 4 above scenarios,the corresponding traffic delays are compared to evaluate their impact on traffic operation.Nanjing is taken as a case study for the simulation analysis.The re-sults show that the number of

  2. Discussion on Design of Track Joining of Departure and Arrival Track of Vehicle Depot of Urban Rail Transit%轨道交通车辆段出入线接轨方案设计探索

    Institute of Scientific and Technical Information of China (English)

    高华

    2012-01-01

    研究目的:车辆段出入线接轨方案研究是轨道交通前期设计中的一个重要课题,本文通过对无锡地铁1号线西漳车辆段出入线的一站接轨方案和两站接轨方案进行比较后,从接轨站车站规模、线路条件、行车干扰程度、折返以及出段作业效率、建设投资等因素出发,综合分析,最终确定了最合理方案.研究结论:(1)出入线应本着方便运营、优化平纵断面条件,减少与正线的行车干扰,提高列车折返、出入段作业效率,降低运营成本等要素来选择合适的接轨方式.(2)在轨道交通设计中,应结合车辆段的段址,正线线路条件、车站规模,行车,运营,投资等多种因素,选择相对合理的接轨方式.有条件时可结合段型布置,实现列车调头转向功能.(3)在选择车辆段出入线的接轨方式时,应从区域规划,项目建成后的社会效益,经济效益等多方面考虑,确定最合理方案.%Research purposes:The research on the track joining of the departure and arrival track of the vehicle depot is a very important work in the prophase design. In this paper, through comprehensively analyzing and comparing the schemes for the one - station track joining and two - station track joining of the departure and arrival track of the Xizhang Vehicle Depot of Line 1 of the Wuxi metro, the analysis is made from areas of the scale of the station where the track joins, track conditions, the interference degree on the traffic, the turn -back operation, the operation efficiency of the train departing the depot and the construction investment so as to decide the most reasonable scheme.Research conclusions: The factors of the easy operation, optimization of the plane and vertical sections conditions, reduction of the traffic interference on the main track, improvement of the operation efficiencies of the train turning back and departing and arriving at the depot and reduction of the operation cost should be

  3. 非球面玻璃模造用碳化钨模仁磁控溅射铼-铱镀膜工艺优化%Optimization of magnetron sputtering of rhenium-iridium coating on mold core (tungsten carbide) used for aspheric glass molding

    Institute of Scientific and Technical Information of China (English)

    杜琪健

    2012-01-01

    通过钽过渡镀层与铼-铱复合镀层相结合的膜层结构,解决了非球面玻璃模造碳化钨模仁热压寿命短、沾黏等问题.通过离子源和镀膜层厚度参数的优化调整,得到了最佳镀膜工艺和参数,改善了模仁的表面品质,延长了模仁的使用寿命.镀钽膜层15 min及铼-铱膜层21 min后所得镀膜的总厚度约为270 nm,模仁热压寿命可超过3 000次.%The problems of short service life and sticking of tungsten carbide (WC) mold core used for aspheric glass molding were solved by combination of tantalum mediate coating and rhenium-indium composite coating. The parameters of ion source and coating thickness were optimized and the optimal plating conditions were obtained. The surface quality of mold core was improved and its service life greatly extended. The molding core with a coating having a total thickness of ca.270 nm obtained by successively plating Ta for 15 min and Re-Ir for 21 min can be reused for more than 3 000 times in hot embossing.

  4. Profile measurement of concave spherical mirror and a flat mirror using a high-speed nanoprofiler.

    Science.gov (United States)

    Usuki, Koji; Kitayama, Takao; Matsumura, Hiroki; Kojima, Takuya; Uchikoshi, Junichi; Higashi, Yasuo; Endo, Katsuyoshi

    2013-05-16

    Ultraprecise aspheric mirrors that offer nanofocusing and high coherence are indispensable for developing third-generation synchrotron radiation and X-ray free-electron laser sources. In industry, the extreme ultraviolet (wavelength: 13.5 nm) lithography used for high-accuracy aspheric mirrors is a promising technology for fabricating semiconductor devices. In addition, ultraprecise mirrors with a radius of curvature of less than 10 mm are needed in many digital video instruments. We developed a new type of nanoprofiler that traces the normal vector of a mirror's surface. The principle of our measuring method is that the normal vector at each point on the surface is determined by making the incident light beam on the mirror surface and the reflected beam at that point coincide, using two sets of two pairs of goniometers and one linear stage. From the acquired normal vectors and their coordinates, the three-dimensional shape is calculated by a reconstruction algorithm. The characteristics of the measuring method are as follows: the profiler uses the straightness of laser light without using a reference surface. Surfaces of any shape can be measured, and there is no limit on the aperture size. We calibrated this nanoprofiler by considering the system error resulting from the assembly error and encoder scale error, and evaluated the performance at the nanometer scale. We suppressed the effect of random errors by maintaining the temperature in a constant-temperature room within ±0.01°C. We measured a concave spherical mirror with a radius of curvature of 400 mm and a flat mirror and compared the results with those obtained using a Fizeau interferometer. The profiles of the mirrors were consistent within the range of system errors.

  5. Clinical observation on visual quality in patients implanted with monofocal and multifocal aspheric intraocular lenses%多焦点与单焦点非球面人工晶状体植入后视觉质量的临床观察

    Institute of Scientific and Technical Information of China (English)

    王文莹; 王军; 张晶; 赵世强; 马剑欣

    2010-01-01

    眼近视力较好,阅读脱镜率较高,具有较好的视觉功能,但对比敏感度有所下降.%Objective To evaluate the visual quality in patients implanted with aspheric diffractive multifocal intraocular lens. Methods Prospective nonrandomized controlled study. One hundred cataract eyes in 50 patients were included. Patients received AcrySof IQ ReSTOR IOL (SN6AD3) or AcrySof IQ IOL (SN60WF) implantation. The follow up period was 6 months. The mean of unconnected distance visual acuity ( UCDVA) , best corrected distance visual acuity ( BCDVA), unconnected near visual acuity (UCNVA), best distance-corrected near visual acuity (BCNVA) and intermediate unconrrected visual acuity in patients with SN6AD3 and SN60WF was compared preoperatively and postoperatively in all patients. Photopic and mesopic contrast sensitivity function with and without glare were tested at 6 months after operation. Aberrations were recorded postoperatively. Subjective outcomes were assessed by VF-14 questionnaire. The chi-square test was applied to compare categorical variables and the paired-samples t test was used to compare the measure data. Results Postoperatively, there were no significant differences between groups in spherical equivalent (SE) (t=0.233, P = 0.876), UCDVA (t = 1.018, P=0.265) or BCNVA (t = 0. 679, P = 0. 501). The BCDVA in the monofocal IOL group was better than that in the multifocal IOL group (t = 2. 388, P = 0. 021). UCNVA improved remarkably after the implantation of multifocal IOL (t = 11. 311 ,P =0.000). The intermediate UCVA in the monofocal IOL eyes was butter than that in the multifocal IOL at 60 cm(t =2.414,P=0.020). The total aberration (F = 5. 169,P =0. 041), total low grade (F =4.973,P =0.036) and total high grade total aberrations (F =4.640,P = 0.048) were higher in the multifocal IOL group. There was no difference between these two groups in the defocus ( F = 0.862, P=0.358), astigmatism(F=3.893, P=0.052), spherical aberration(F = 1.743, P=0

  6. Numerical prediction of nucleate pool boiling heat transfer coefficient under high heat fluxes

    OpenAIRE

    Pezo Milada L.; Stevanović Vladimir D.

    2016-01-01

    This paper presents CFD (Computational Fluid Dynamics) approach to prediction of the heat transfer coefficient for nucleate pool boiling under high heat fluxes. Three-dimensional numerical simulations of the atmospheric saturated pool boiling are performed. Mathematical modelling of pool boiling requires a treatment of vapor-liquid two-phase mixture on the macro level, as well as on the micro level, such as bubble growth and departure from the heating surfa...

  7. Application of the Ecosystem Disturbance and Recovery Tracker in Detection of Forest Health Departure from Desired Conditions in Sierra Nevada National Forests

    Science.gov (United States)

    Slaton, M.; Koltunov, A.; Ramirez, C.

    2016-12-01

    Three Sierra Nevada national forests have recently released draft revised land management plans to the public for comment. These plans include components guiding land management projects (e.g. timber harvest) over the next decades. Desired conditions for land cover types were identified, and are based on the concept of the natural range of variability (NRV); the agency aims to achieve vegetation structure and composition that is within the range that has occurred in that system during the Holocene, prior to Euro-American settlement. Such systems are identified as having ecological integrity, with the ability to withstand and recover from disturbance. Comparisons between current conditions and the NRV period are often made qualitatively, with quantitative comparisons possible through the reconstruction of forest parameters using paleoecological evidence such as pollen or tree rings. Where such information is lacking, comparisons can be made using more recent data for locations or time periods believed to closely represent NRV. Such evaluations are necessary to develop projects that will be within the agency's desired conditions. As an example, the most recent estimate of the extent of tree mortality in CA continues to rise and expand at an aggressive rate, creating the need to track progress as compared to baseline conditions. The Ecosystem Disturbance and Recovery Tracker (eDaRT) is a system developed by the US Forest Service Region 5 Remote Sensing Lab and UC Davis CSTARS center that uses all available Landsat imagery to detect anomalies in vegetation indices, and has been adapted to detect current tree mortality as compared to modern pre-drought baseline conditions. We present initial results for the southern Sierra Nevada (5,260,913 hectares; 13 million acres) that have been validated using WorldView imagery and field data. The high spatial resolution and large extent of the dataset as compared to other mortality maps enabled identification of factors correlated

  8. Departures from plane-wave-like coupling to a Maverick missile in the radiating near-field region of a horn antenna

    Science.gov (United States)

    Voss, D. E.; Koslover, R. A.; Cremer, C. D.; Silvestro, J.; Miner, L. M.

    1990-05-01

    The High Power Microwaves (HPM) susceptibility testing often requires irradiating test objects at the highest fluences possible. For aperture antennas, the highest fluences are generally found in the radiating near field region. For valid effects testing, the energy coupled to the object interior must accurately replicate that which would occur in a true weapon environment (plane wave illumination). Some believe that valid testing requires object placement at distances from the aperture exceeding 2 D squared/lambda (D=antenna effective diameter). Many also believe testing at farther away than 2 D squared/lambda guarantees plane wave-like coupling conditions. Neither view is correct. Testing in the reactive field region (less than lambda from the aperture) is generally invalid due to dominance of reactive coupling. For testing in the radiating near field, determination of validity is less trivial. An investigation was performed quantifying deviations from plane wave coupling. The measurements, using an instrumented Maverick missile in an anechoic chamber, and supported by theory, indicate conditions for which testing the Maverick missile accurately simulates plane wave coupling.

  9. Factors influencing adjustment of high school students in an international exchange program.

    Science.gov (United States)

    Furukawa, T; Shibayama, T

    1994-12-01

    The present study aims to investigate which psychosocial factors measured before departure are predictive of various aspects of intercultural adjustment among Japanese teenagers enrolled in a foreign exchange student program. A cohort of 188 Japanese high school students, who had been selected to spend 1 year in various countries of the world under the aegis of an international exchange student program, was administered the Maudsley Personality Inventory, the Parental Bonding Instrument, the General Health Questionnaire and the People in Your Life Scale before their departure from Japan. Six months after arrival in the host community, they were again asked to complete the General Health Questionnaire and relevant sections of the People in Your Life Scale. The students showed highly significant and substantial deterioration in all three areas of psychosocial adjustment: they reported more psychiatric symptoms, less availability of social relationships, and less satisfaction with them in their host community than at home. Psychiatric symptoms were best predicted by perceived adequacy of intimate attachments and neuroticism measured before departure, availability of social relationships abroad by availability and adequacy of social relationships and adequacy of attachments at home, and satisfaction with social relationships abroad by satisfaction with attachments at home and by paternal care before age 16. This study thus demonstrates that studying abroad entails deterioration in psychosocial adjustment of the adolescents studied and that different factors are influential in different aspects of adjustment. The importance of a prospective and multifaceted study of intercultural adjustment process is emphasized.

  10. Four Departures in Mathematics and Physics

    CERN Document Server

    Rosinger, Elemer E

    2010-01-01

    Much of Mathematics, and therefore Physics as well, have been limited by four rather consequential restrictions. Two of them are ancient taboos, one is an ancient and no longer felt as such bondage, and the fourth is a surprising omission in Algebra. The paper brings to the attention of those interested these four restrictions, as well as the fact that each of them has by now ways, even if hardly yet known ones, to overcome them.

  11. Departure from Washington / Jüri Luik

    Index Scriptorium Estoniae

    Luik, Jüri, 1966-

    2008-01-01

    Ülevaade Eesti-USA suhetest ja rahvusvahelisest olukorrast aastatel 2003-2007. Artikli autor oli aastatel 2003-2007 Eesti Vabariigi suursaadik Ameerika Ühendriikides. Juttu on ka president Toomas Hendrik Ilvese visiidist Valgesse Majja ja kohtumisest USA presidendi George W. Bushiga 2007. a. juunis

  12. Modeling Departure Time Choice with Stochastic Networks

    NARCIS (Netherlands)

    Li, H.; Bliemer, M.C.J.; Bovy, P.H.L.

    2010-01-01

    Stochastic supply and fluctuating travel demand lead to stochasticity in travel times and travel costs experienced by travelers from time to time within a day and at the same time from day to day. Many studies show that travel time un-reliability has significant impacts on traveler’s choice behavior

  13. Departure or termination?; Aufbruch oder Abbruch?

    Energy Technology Data Exchange (ETDEWEB)

    Bell, John

    2013-06-15

    Fracking is the hope of the gas industry. But the tearing of rock formations in depth of 1,000 meters splits the energy and water sector. [German] Fracking ist die Hoffnung der Gasbranche. Doch das Aufreissen von Gesteinsformationen in 1.000 Meter Tiefe spaltet die Energie- und Wasserwirtschaft.

  14. Departure from Washington / Jüri Luik

    Index Scriptorium Estoniae

    Luik, Jüri, 1966-

    2008-01-01

    Ülevaade Eesti-USA suhetest ja rahvusvahelisest olukorrast aastatel 2003-2007. Artikli autor oli aastatel 2003-2007 Eesti Vabariigi suursaadik Ameerika Ühendriikides. Juttu on ka president Toomas Hendrik Ilvese visiidist Valgesse Majja ja kohtumisest USA presidendi George W. Bushiga 2007. a. juunis

  15. SU(5) and New Departures in Unification

    Science.gov (United States)

    Pakvasa, S.; Tuan, S. F.

    1982-01-01

    "Just as today, most of us are certain of the validity of SU(2) × U(l) even though we have not seen a W or Z, so also if proton decay is seen at the expected rate, we can presume that unification involves SU(S). Indeed, our faith in SU(2) × U(l) is not based entirely on hard experimental evidence. There is an infinite class of theories which give the same neutral current structure. But compared to SU(2) × U(l), the alternatives are complicated, unnatural and ugly. My faith in SU(5) is likewise based on my belief that the world is simple and beautiful." --Howard Georgi

  16. Categorical Design Departure and Symbolic Enhancement

    DEFF Research Database (Denmark)

    Krabbe, Anders Dahl

    Previous research has tended to assume that the role of product form design in the early stages of technology lifecycles is to decrease the cognitive distance between the new product and previous designs within the given product category. This paper will contrast this tendency in the literature...... by showing how product form design can impact the selection of dominant technological designs within industries by enhancing the symbolic attributes of products. A longitudinal case study was carried out of the establishment of a new dominant technological architecture in the hearing aid industry...

  17. Advancing a distributed multi-scale computing framework for large-scale high-throughput discovery in materials science.

    Science.gov (United States)

    Knap, J; Spear, C E; Borodin, O; Leiter, K W

    2015-10-30

    We describe the development of a large-scale high-throughput application for discovery in materials science. Our point of departure is a computational framework for distributed multi-scale computation. We augment the original framework with a specialized module whose role is to route evaluation requests needed by the high-throughput application to a collection of available computational resources. We evaluate the feasibility and performance of the resulting high-throughput computational framework by carrying out a high-throughput study of battery solvents. Our results indicate that distributed multi-scale computing, by virtue of its adaptive nature, is particularly well-suited for building high-throughput applications.

  18. Development of High-Field Permanent Magnetic Circuits for NMRI/MRI and Imaging on Mice

    Directory of Open Access Journals (Sweden)

    Guangxin Wang

    2016-01-01

    Full Text Available The high-field permanent magnetic circuits of 1.2 T and 1.5 T with novel magnetic focusing and curved-surface correction are developed. The permanent magnetic circuit comprises a magnetic yoke, main magnetic steel, nonspherical curved-surface magnetic poles, plugging magnetic steel, and side magnetic steel. In this work, a novel shimming method is proposed for the effective correction of base magnetic field (B0 inhomogeneities, which is based on passive shimming on the telescope aspheric cutting, grinding, and fine processing technology of the nonspherical curved-surface magnetic poles and active shimming adding higher-order gradient coils. Meanwhile, the magnetic resonance imaging dedicated alloy with high-saturation magnetic field induction intensity and high electrical resistivity is developed, and nonspherical curved-surface magnetic poles which are made of the dedicated alloy have very good anti-eddy-current effect. In addition, the large temperature coefficient problem of permanent magnet can be effectively controlled by using a high quality temperature controller and deuterium external locking technique. Combining our patents such as gradient coil, RF coil, and integration computer software, two kinds of small animal Micro-MRI instruments are developed, by which the high quality MRI images of mice were obtained.

  19. Synthesis of multi-wavelength temporal phase-shifting algorithms optimized for high signal-to-noise ratio and high detuning robustness using the frequency transfer function

    CERN Document Server

    Servin, Manuel; Garnica, Guillermo

    2016-01-01

    Synthesis of single-wavelength temporal phase-shifting algorithms (PSA) for interferometry is well-known and firmly based on the frequency transfer function (FTF) paradigm. Here we extend the single-wavelength FTF-theory to dual and multi-wavelength PSA-synthesis when several simultaneous laser-colors are present. The FTF-based synthesis for dual-wavelength PSA (DW-PSA) is optimized for high signal-to-noise ratio and minimum number of temporal phase-shifted interferograms. The DW-PSA synthesis herein presented may be used for interferometric contouring of discontinuous industrial objects. Also DW-PSA may be useful for DW shop-testing of deep free-form aspheres. As shown here, using the FTF-based synthesis one may easily find explicit DW-PSA formulae optimized for high signal-to-noise and high detuning robustness. To this date, no general synthesis and analysis for temporal DW-PSAs has been given; only had-hoc DW-PSAs formulas have been reported. Consequently, no explicit formulae for their spectra, their sign...

  20. Design and fabrication of aspherical bimorph PZT optics

    CERN Document Server

    Tseng, T C; Yeh, Z C; Perng, S Y; Wang, D J; Kuan, C K; Chen, J R; Chen, C T

    2001-01-01

    Bimorph piezoelectric optics with a third-order-polynomial surface is designed and a prototype is fabricated as active optics. Two pairs of silicon (Si) and lead zirconate titanate (PZT) piezoelectric ceramic are bonded as Si-PZT-PZT-Si together with a multi-electrode or thin film resistor coating used as the control electrode between Si and PZT and metallic films as grounding between the interface of PZT ceramics. A linear voltage is applied to the bimorph PZT optics by probing the control electrodes from a two-channel controllable power supplier. In doing so, the optics surface can achieve a desired third-order-polynomial surface. Reducing hysteresis and creep in bimorph PZT X-ray optics is the only feasible way by inserting an appropriate capacitor in series with bimorph PZT optics to significantly reduce both effects.

  1. Effect of asphericity in caustic mass estimates of galaxy clusters

    CERN Document Server

    Svensmark, Jacob; Hansen, Steen H

    2014-01-01

    The caustic technique of mass estimation of galaxy clusters relies on the assumption of spherical symmetry, which is not always a valid assumption. Here we demonstrate the effect of spatial anisotropy of galaxy clusters on the inferred caustic mass profiles by considering particle data from dark matter N-body simulations. We find a factor of ~3 discrepancy between major and minor axis mass estimates in ellipsoidal clusters within the virial radius Rv, and up to ~5 within 3 Rv. We also find filaments to influence caustic mass estimates at a comparable magnitude. By stacking halos to align their principal axes we find that a line of sight along the major axis overestimates the caustic mass of galaxy clusters, as well as a line of sight along the minor axis underestimates it. The mass discrepancy between the major and minor axis is a factor of 2.47, 2.97 and 3.95 at 1, 2 and 3 Rv for virial masses Mv = [1,2] x 10^{14} Msun/h, and $(30-35)\\%$ larger for Mv > 2 x 10^{14} Msun/h. Furthermore, the caustic mass is ov...

  2. Subaperture Stitching Interferometry for Large Convex Aspheric Surfaces Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The size and accuracy specifications of telescope mirrors are ever more demanding. This is particularly true for secondary mirrors, as they are convex and thus...

  3. Fabrication of strongly curved aspheric silicon carbide mirrors

    NARCIS (Netherlands)

    Gubbels, G.P.H.; Drunen, C. van; Böhm, G.; Arnold, T.; Kamphues, F.G.; Gielesen, W.L.M.

    2010-01-01

    TNO Science and Industry has designed and is currently developing the Basic Angle Monitoring Opto-Mechanical Assembly (BAM OMA) [1], which is part of the GAIA spacecraft. In GAIA two telescopes mounted on a slowly spinning satellite will measure the position of the stars with an accuracy much higher

  4. Optical Fabrication and Metrology of Aspheric and Freeform Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The requirement for cost effective manufacturing and metrology of large optical surfaces is instrumental for the success of future NASA programs such as LISA, WFIRST...

  5. Optical design of the PEPSI high-resolution spectrograph at LBT

    Science.gov (United States)

    Andersen, Michael I.; Spano, Paolo; Woche, Manfred; Strassmeier, Klaus G.; Beckert, Erik

    2004-09-01

    PEPSI is a high-resolution, fiber fed echelle spectrograph with polarimetric capabilities for the LBT. In order to reach a maximum resolution R=120.000 in polarimetric mode and 300.000 in integral light mode with high efficiency in the spectral range 390-1050~nm, we designed a white-pupil configuration with Maksutov collimators. Light is dispersed by an R4 31.6 lines/mm monolithic echelle grating mosaic and split into two arms through dichroics. The two arms, optimized for the spectral range 390-550~nm and 550-1050~nm, respectively, consist of Maksutov transfer collimators, VPH-grism cross dispersers, optimized dioptric cameras and 7.5K x 7.5K 8~μ CCDs. Fibers of different core sizes coupled to different image-slicers allow a high throughput, comparable to that of direct feed instruments. The optical configuration with only spherical and cylindrical surfaces, except for one aspherical surface in each camera, reduces costs and guarantees high optical quality. PEPSI is under construction at AIP with first light expected in 2006.

  6. Visual processing of configuration-dependent spatial characteristics of shapes and patterns. A model useful in the study of the role of the departure from circularity or dispersion of shapes in human visual perception.

    Science.gov (United States)

    Bonciocat, C A; Grosu, G; Ghiţă, S

    1997-01-01

    In this work a theoretical model was used in combination with testings on normal subjects to get more insight in the role of the departure from circularity or dispersion of the shapes in visual perception. The model was inspired by the observation that the intensity of the effect of a given level of contrast of a shape usually increases, for the same area, with the shape being better concentrated around a center. The model introduces as a measurable characteristic the degree of concentration or dispersion of a shape with respect to a center. The measure was based on the maximum of the convolution integral of the characteristic function of the shape with the weighting function 1/2 pi r, r being the distance between the point of convolution and the surface element to be integrated. A program for the calculation of the degree of concentration of figures and other related processing operations was developed in Turbo Pascal language on a 486 PC. The program included the possibility to generate various figures and to operate on them various transformations such as strangulation, fragmentation with separation of fragments. The model introduces a center of the figure, the point best surrounded by the whole figure, with a geometric and visual significance, as resulting from the good concordance between its calculated and perceived positioning in different relatively simple shapes. In symmetrical compact figures subjected to a central separation or narrowing two centres appear entering the two resulting nuclear parts; a good concordance between model and perception was again observed in this transition to two centres and their subsequent positions in the two nuclear parts. In accord to model prediction, testings showed a very pronounced dependence of the summation efficiency over a contrasting area on the degree of dispersion of the area. This is reflected in the drastic decrease upon figure dispersion of the intensity with which a given brightness or colour contrast is

  7. High-precision photometry by telescope defocussing. VII. The ultra-short period planet WASP-103

    CERN Document Server

    Southworth, John; Ciceri, S; Budaj, J; Dominik, M; Jaimes, R Figuera; Haugbolle, T; Jorgensen, U G; Popovas, A; Rabus, M; Rahvar, S; von Essen, C; Schmidt, R W; Wertz, O; Alsubai, K A; Bozza, V; Bramich, D M; Novati, S Calchi; D'Ago, G; Hinse, T C; Henning, Th; Hundertmark, M; Juncher, D; Korhonen, H; Skottfelt, J; Snodgrass, C; Starkey, D; Surdej, J

    2014-01-01

    We present 17 transit light curves of the ultra-short period planetary system WASP-103, a strong candidate for the detection of tidally-induced orbital decay. We use these to establish a high-precision reference epoch for transit timing studies. The time of the reference transit midpoint is now measured to an accuracy of 4.8s, versus 67.4s in the discovery paper, aiding future searches for orbital decay. With the help of published spectroscopic measurements and theoretical stellar models, we determine the physical properties of the system to high precision and present a detailed error budget for these calculations. The planet has a Roche lobe filling factor of 0.58, leading to a significant asphericity; we correct its measured mass and mean density for this phenomenon. A high-resolution Lucky Imaging observation shows no evidence for faint stars close enough to contaminate the point spread function of WASP-103. Our data were obtained in the Bessell $RI$ and the SDSS $griz$ passbands and yield a larger planet ...

  8. High-Speed Bullet Ejections during the AGB to Planetary Nebula Transition: HST Observations of the Carbon Star, V Hydrae

    CERN Document Server

    Sahai, R; Morris, M R

    2016-01-01

    The well-studied carbon star, V Hya, showing evidence for high-speed, collimated outflows and dense equatorial structures, is a key object in the study of the poorly understood transition of AGB stars into aspherical planetary nebulae. Using the STIS instrument onboard HST, we have obtained high spatial-resolution long-slit optical spectra of V Hya that show high-velocity emission in [SII] and [FeII] lines. Our dataset, spanning three epochs spaced apart by a year during each of two periods (in 2002-2004 and 2011-2013), shows that V Hya ejects high-speed (about 200-250 km/s) bullets once every ~8.5 yr. The ejection axis flip-flops around a roughly eastern direction, both in and perpendicular to the sky-plane, and the radial velocities of the ejecta also vary in concert between low and high values. We propose a model in which the bullet ejection is associated with the periastron passage of a binary companion in an eccentric orbit around V Hya with an orbital period of ~8.5 yr. The flip-flop phenomenon is likel...

  9. The study about forming high-precision optical lens minimalized sinuous error structures for designed surface

    Science.gov (United States)

    Katahira, Yu; Fukuta, Masahiko; Katsuki, Masahide; Momochi, Takeshi; Yamamoto, Yoshihiro

    2016-09-01

    Recently, it has been required to improve qualities of aspherical lenses mounted on camera units. Optical lenses in highvolume production generally are applied with molding process using cemented carbide or Ni-P coated steel, which can be selected from lens material such as glass and plastic. Additionally it can be obtained high quality of the cut or ground surface on mold due to developments of different mold product technologies. As results, it can be less than 100nmPV as form-error and 1nmRa as surface roughness in molds. Furthermore it comes to need higher quality, not only formerror( PV) and surface roughness(Ra) but also other surface characteristics. For instance, it can be caused distorted shapes at imaging by middle spatial frequency undulations on the lens surface. In this study, we made focus on several types of sinuous structures, which can be classified into form errors for designed surface and deteriorate optical system performances. And it was obtained mold product processes minimalizing undulations on the surface. In the report, it was mentioned about the analyzing process by using PSD so as to evaluate micro undulations on the machined surface quantitatively. In addition, it was mentioned that the grinding process with circumferential velocity control was effective for large aperture lenses fabrication and could minimalize undulations appeared on outer area of the machined surface, and mentioned about the optical glass lens molding process by using the high precision press machine.

  10. Multidimensional Study of High-Adiabat OMEGA Cryogenic Experiments

    Science.gov (United States)

    Collins, T. J. B.; Betti, R.; Bose, A.; Christopherson, A. R.; Knauer, J. P.; Marozas, J. A.; Maximov, A. V.; Mora, A.; Radha, P. B.; Shang, W.; Shvydky, A.; Stoeckl, C.; Woo, K. M.; Varchas, G.

    2016-10-01

    Despite recent advances in modeling laser direct-drive inertial confinement fusion (ICF) experiments, there remains a predictability gap. This is particularly shown by the shortfall in hot-spot pressures inferred from OMEGA cryogenic implosions. To address this, a series of high-adiabat, cryogenic implosions were performed on OMEGA. These shots were performed with and without single-beam smoothing by spectral dispersion, at low and high drive intensities. These shots represent a regime where good agreement with simulation is expected because of the high adiabat. Multidimensional simulations of these shots will be presented with an emphasis on comparison with experimental indicators of departure from spherical symmetry (``1-D-ness''). The roles of short- and long-wavelength perturbations are considered. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  11. Every photon counts: improving low, mid, and high-spatial frequency errors on astronomical optics and materials with MRF

    Science.gov (United States)

    Maloney, Chris; Lormeau, Jean Pierre; Dumas, Paul

    2016-07-01

    Many astronomical sensing applications operate in low-light conditions; for these applications every photon counts. Controlling mid-spatial frequencies and surface roughness on astronomical optics are critical for mitigating scattering effects such as flare and energy loss. By improving these two frequency regimes higher contrast images can be collected with improved efficiency. Classically, Magnetorheological Finishing (MRF) has offered an optical fabrication technique to correct low order errors as well has quilting/print-through errors left over in light-weighted optics from conventional polishing techniques. MRF is a deterministic, sub-aperture polishing process that has been used to improve figure on an ever expanding assortment of optical geometries, such as planos, spheres, on and off axis aspheres, primary mirrors and freeform optics. Precision optics are routinely manufactured by this technology with sizes ranging from 5-2,000mm in diameter. MRF can be used for form corrections; turning a sphere into an asphere or free form, but more commonly for figure corrections achieving figure errors as low as 1nm RMS while using careful metrology setups. Recent advancements in MRF technology have improved the polishing performance expected for astronomical optics in low, mid and high spatial frequency regimes. Deterministic figure correction with MRF is compatible with most materials, including some recent examples on Silicon Carbide and RSA905 Aluminum. MRF also has the ability to produce `perfectly-bad' compensating surfaces, which may be used to compensate for measured or modeled optical deformation from sources such as gravity or mounting. In addition, recent advances in MRF technology allow for corrections of mid-spatial wavelengths as small as 1mm simultaneously with form error correction. Efficient midspatial frequency corrections make use of optimized process conditions including raster polishing in combination with a small tool size. Furthermore, a novel MRF

  12. 三种非球面单焦点丙烯酸酯人工晶状体植入术后视觉质量的临床观察%Clinical observation on visual function in patients implanted three kinds of aspheric acrylic monofocal intraocular lenses

    Institute of Scientific and Technical Information of China (English)

    冀海轮; 肖伟; 赵芳; 赵岱新; 濮伟

    2013-01-01

    Objective To evaluate best corrected visual acuity(BCVA) and contrast sensitivity(CS) under photopic condition with no glare in patients following implantation of three different kinds of aspheric acrylic monofocal intraocular lens. Methods 77 cases(90 eyes) of age-related cataract patients were selected,who were undergone phacoemulsification and intraocular lens(IOL) implantation in our hospital during December 2011 to November 2012. Preoperatively, the patients were randomly divided into three groups. Group 1 including 30 eyes(25 cases) were implanted with hydrophobic yellow-tinted acrylic IOLs; Group 2(30 eyes of 28 cases) with hydrophilic acrylic IOLs;Group 3(30 eyes of 24 cases) with hydrophilic acrylic surface heparin processing IOLs. All eyes were evaluated at 1 month and 3 months postoperatively. The BCVA and CS under photopic condition without glare were measured and underwent statistical analysis. Results There was neither statistically significant difference in the BCVA(P>0.05), nor statistically significant difference in contrast sensitivity results (after standardization of contrast sensitivity value: lgCS)(P>0.05) between groups. Conclusions There were not marked differences of BCVA and CS between groups of patients at the follow-up intervals of 1 month and 3 months. The blue-filter type artificial lens protect the retina, thus, it is advisable to implant yellow-tinted filter blue artificial lens.%目的:研究三种非球面丙烯酸酯人工晶状体植入术后患者在最佳矫正视力及明视下对比敏感度(contrast sensitivity,CS)的变化,评价白内障超声乳化联合单焦点非球面丙烯酸酯人工晶状体植入术后患者的视觉质量。方法选择2011年12月至2012年11月期间于我院行白内障超声乳化吸除联合人工晶状体植入术的年龄相关性白内障患者77例(90眼)。术前将患者随机分成三组:A组(25例,30眼)植入疏水性染黄色

  13. Challenges in mold manufacturing for high precision molded diffractive optical elements

    Science.gov (United States)

    Pongs, Guido; Bresseler, Bernd; Schweizer, Klaus; Bergs, Thomas

    2016-09-01

    Isothermal precision glass molding of imaging optics is the key technology for mass production of precise optical elements. Especially for numerous consumer applications (e.g. digital cameras, smart phones, …), high precision glass molding is applied for the manufacturing of aspherical lenses. The usage of diffractive optical elements (DOEs) can help to further reduce the number of lenses in the optical systems which will lead to a reduced weight of hand-held optical devices. But today the application of molded glass DOEs is limited due to the technological challenges in structuring the mold surfaces. Depending on the application submicrometer structures are required on the mold surface. Furthermore these structures have to be replicated very precisely to the glass lens surface. Especially the micro structuring of hard and brittle mold materials such as Tungsten Carbide is very difficult and not established. Thus a multitude of innovative approaches using diffractive optical elements cannot be realized. Aixtooling has investigated in different mold materials and different suitable machining technologies for the micro- and sub-micrometer structuring of mold surfaces. The focus of the work lays on ultra-precision grinding to generate the diffractive pattern on the mold surfaces. This paper presents the latest achievements in diffractive structuring of Tungsten Carbide mold surfaces by ultra-precision grinding.

  14. Photoemission, low-dimensionality and high-temperature superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Margaritondo, G. [Ecole Polytechnique Federale, Lausanne (Switzerland). Inst. de Physique Appliquee]|[Sincrotrone Trieste SCpA (Italy)

    1996-12-31

    Several experiments by different authors have established the existence of an anomalous photoemission effect in one-dimensional systems, including one-dimensional metallic crystals and other examples of one-dimensional metals. The effect consists of the suppression of the photoemission signal at energies close to the Fermi level--whereas for metals one would expect to see a Fermi edge. Increasing evidence exists, in the authors opinion, that this phenomenon is due to the decoupling of charge and spin coordinates and to a departure from the Fermi-liquid framework. If confirmed, this conclusion would be extremely relevant to high-temperature superconductivity, since it would pave the way to the use of a similar concept for non-Fermi-liquid theories of high-temperature superconductors.

  15. Spiraling Away from Vesta: Design of the Transfer from the Low to High Altitude Dawn Mapping Orbits

    Science.gov (United States)

    Smith, John C.; Parcher, Daniel W.; Whiffen, Gregory J.

    2013-01-01

    Dawn has successfully completed its orbital mission at Vesta and is currently en route to an orbital rendezvous with Ceres in 2015. The longest duration and most complex portion of the Vesta departure trajectory was the transfer from the low to high altitude science orbit. This paper describes the design of this low-thrust trajectory optimized assuming a minimum-propellant mass objective. The transfer utilized solar-electric ion propulsion applied over 139 spacecraft revolutions about Vesta. Science drivers, operational constraints, and robustness to statistical uncertainties are addressed. The 45-day transfer trajectory was successfully implemented in early 2012.

  16. Coincidences between gravitational wave interferometers and high energy neutrino telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Pradier, Thierry [Institut Pluridisciplinaire Hubert Curien (IPHC/DRS), University Louis-Pasteur, Strasbourg (France)], E-mail: pradier@in2p3.fr

    2009-04-11

    Sources of gravitational waves (GW) and emitters of high energy neutrinos (HE {nu}) both involve compact objects and matter moving at relativistic speeds. GW emission requires a departure from spherical symmetry, which is the case if clumps of matter are accreted around black holes or neutron stars, and ejected in relativistic jets, where neutrinos are believed to be produced. Both messengers interact weakly with the surrounding matter, hence point directly to the heart of the engines that power these emissions. Coincidences between GW interferometers (e.g. VIRGO) and HE {nu} telescopes (e.g. ANTARES) would then give a unique insight on the physics of the most powerful objects in the Universe. The possibility, observability and detectability for such GW/HE {nu} coincidences are analysed.

  17. An angle encoder for super-high resolution and super-high accuracy using SelfA

    Science.gov (United States)

    Watanabe, Tsukasa; Kon, Masahito; Nabeshima, Nobuo; Taniguchi, Kayoko

    2014-06-01

    Angular measurement technology at high resolution for applications such as in hard disk drive manufacturing machines, precision measurement equipment and aspherical process machines requires a rotary encoder with high accuracy, high resolution and high response speed. However, a rotary encoder has angular deviation factors during operation due to scale error or installation error. It has been assumed to be impossible to achieve accuracy below 0.1″ in angular measurement or control after the installation onto the rotating axis. Self-calibration (Lu and Trumper 2007 CIRP Ann. 56 499; Kim et al 2011 Proc. MacroScale; Probst 2008 Meas. Sci. Technol. 19 015101; Probst et al Meas. Sci. Technol. 9 1059; Tadashi and Makoto 1993 J. Robot. Mechatronics 5 448; Ralf et al 2006 Meas. Sci. Technol. 17 2811) and cross-calibration (Probst et al 1998 Meas. Sci. Technol. 9 1059; Just et al 2009 Precis. Eng. 33 530; Burnashev 2013 Quantum Electron. 43 130) technologies for a rotary encoder have been actively discussed on the basis of the principle of circular closure. This discussion prompted the development of rotary tables which achieve reliable and high accuracy angular verification. We apply these technologies for the development of a rotary encoder not only to meet the requirement of super-high accuracy but also to meet that of super-high resolution. This paper presents the development of an encoder with 221 = 2097 152 resolutions per rotation (360°), that is, corresponding to a 0.62″ signal period, achieved by the combination of a laser rotary encoder supplied by Magnescale Co., Ltd and a self-calibratable encoder (SelfA) supplied by The National Institute of Advanced Industrial Science & Technology (AIST). In addition, this paper introduces the development of a rotary encoder to guarantee ±0.03″ accuracy at any point of the interpolated signal, with respect to the encoder at the minimum resolution of 233, that is, corresponding to a 0.0015″ signal period after

  18. Enhanced monolithic diffraction gratings with high efficiency and reduced polarization sensitivity for remote sensing applications

    Science.gov (United States)

    Triebel, Peter; Diehl, Torsten; Moeller, Tobias; Gatto, Alexandre; Pesch, Alexander; Erdmann, Lars H.; Burkhardt, Matthias; Kalies, Alexander

    2015-10-01

    Spectral imaging systems lead to enhanced sensing properties when the sensing system provides sufficient spectral resolution to identify materials from its spectral reflectance signature. The performance of diffraction gratings provides an initial way to improve instrumental resolution. Thus, subsequent manufacturing techniques of high quality gratings are essential to significantly improve the spectral performance. The ZEISS unique technology of manufacturing real-blazed profiles and as well as lamellar profiles comprising transparent substrates is well suited for the production of transmission gratings. In order to reduce high order aberrations, aspherical and free-form surfaces can be alternatively processed to allow more degrees of freedom in the optical design of spectroscopic instruments with less optical elements and therefore size and weight advantages. Prism substrates were used to manufacture monolithic GRISM elements for UV to IR spectral range. Many years of expertise in the research and development of optical coatings enable high transmission anti-reflection coatings from the DUV to the NIR. ZEISS has developed specially adapted coating processes (Ion beam sputtering, ion-assisted deposition and so on) for maintaining the micro-structure of blazed gratings in particular. Besides of transmission gratings, numerous spectrometer setups (e.g. Offner, Rowland circle, Czerny-Turner system layout) working on the optical design principles of reflection gratings. This technology steps can be applied to manufacture high quality reflection gratings from the EUV to the IR applications with an outstanding level of low stray light and ghost diffraction order by employing a combination of holography and reactive ion beam etching together with the in-house coating capabilities. We report on results of transmission gratings on plane and curved substrates and GRISM elements with enhanced efficiency of the grating itself combined with low scattered light in the angular

  19. Meta-analysis on correlation of the departure Intention and organizational commitment of Chinese mainland nurses%中国大陆地区护士离职意愿与组织承诺相关性研究的Meta分析

    Institute of Scientific and Technical Information of China (English)

    唐秀珍; 余红; 刘常青

    2016-01-01

    Objective:To discuss the correlation of Chinese mainland nurses′departure intention and organizational commitment. Methods:Relevant studies were searched using e-Cochrane Library,PubMed,EMbase,Ovid,ISI Web of Knowledge,CBM,CNKI,VIP database and Wan Fang Data, starting from the foundation day of these databases to October 31,2014. Comprehensive Meta-analysis was made by adopting CMA2. 0 statistics software after the selection and withdraw of studies used inclusion and exclusion criteria and the evaluation of quality of inclusion research. Results:A total of 6 studies involving 3496 research subjects were included. The result of analysis shows that mainland China nurses′departure intention was in negative correlation with the their organ-izationalcommitment,andthemergingeffectvaluerwand95% ofCIwas0.431( -0.491,-0.366),whichwasofstatisticalsignificance(P<0.05). Conclusion:Enhancing the overall level of nurses′organizational commitment can effectively reduce the clinical nurses′departure. Managing personnel should fully consider the nurse′s individual characteristics,and avoid the negative effects due to the characteristics of the work to create a harmonious,healthy,posi-tive work environment and cultural atmosphere and strengthen the supports both from the nurse′s family and society.%目的::探讨中国大陆地区护士离职意愿与组织承诺的相关性。方法:计算机检索e Cochrane Library,PubMed,EMbase,Ovid,ISI Web of Knowledge,CBM,CNKI,VIP和WanFang Data数据库,检索时限均为从建库起至2014年10月31日,查找关于中国大陆地区护士离职意愿与组织承诺相关性的文献。按照纳入与排除标准筛选文献、提取资料并评价纳入研究的质量后,采用CMA 2.0统计软件进行Meta分析。结果:最终纳入6篇文献,共3496名调查对象。 Meta分析结果显示,中国大陆地区护士离职意愿与组织承诺呈负相关,合并效应值rw及95% CI为-0.431(-0.491,-0.366),

  20. Very fast transmissive spectrograph designs for highly multiplexed fiber spectroscopy

    CERN Document Server

    Saunders, Will

    2016-01-01

    Very fast (f/1.2 and f/1.35) transmissive spectrograph designs are presented for Hector and MSE. The designs have 61mm x 61mm detectors, 4 or 5 camera lenses of aperture less than 228mm, with just 6 air/glass surfaces, and rely on extreme aspheres for their imaging performance. The throughput is excellent, because of the i-line glasses used, the small number of air/glass surfaces.

  1. Flow-induced birefringence: the hidden PSF killer in high performance injection-molded plastic optics

    Science.gov (United States)

    Chidley, Matthew D.; Tkaczyk, Tomasz; Kester, Robert; Descour, Michael R.

    2006-02-01

    A 7-mm OD, NA = 1 water immersion injection-molded plastic endoscope objective has been fabricated for a laser scanning fiber confocal reflectance microscope (FCRM) system specifically designed for in vivo detection of cervical and oral pre-cancers. Injection-molded optics was selected for the ability to incorporate aspheric surfaces into the optical design and its high volume capabilities. Our goal is high performance disposable endoscope probes. This objective has been built and tested as a stand-alone optical system, a Strehl ratio greater than 0.6 has been obtained. One of the limiting factors of optical performance is believed to be flow-induced birefringence. We have investigated different configurations for birefringence visualization and believe the circular polariscope is most useful for inspection of injection-molded plastic optics. In an effort to decrease birefringence effects, two experiments were conducted. They included: (1) annealing of the optics after fabrication and (2) modifying the injection molding prameters (packing pressures, injection rates, and hold time). While the second technique showed improvement, the annealing process could not improve quality without physically warping the lenses. Therefore, to effectively reduce flow-induced birefringence, molding conditions have to be carefully selected. These parameters are strongly connected to the physical part geometry. Both optical design and fabrication technology have to be considered together to deliver low birefringence while maintaining the required manufacturing tolerances. In this paper we present some of our current results that illustrate how flow-induced birefringence can degrade high performance injection-molded plastic optical systems.

  2. Numerical Simulation on CCOS Controllable Variable

    Institute of Scientific and Technical Information of China (English)

    CHENG Hao-bo; FENG Zhi-jing

    2003-01-01

    On the basis of Preston hypothesis,the motion relationship between tool and workpiece upon the tool's motion in planar model is analyzed.The effect on computer controlled optical surfacing (CCOS) caused by controllable variable is simulated except for the dwelling time,thus,some reference on theory is provided to optimize the former numerical control (NC) model,and fast manufacturing of large departure aspherics is realized.

  3. High-Resolution, Wide-Field-of-View Scanning Telescope

    Science.gov (United States)

    Sepulveda, Cesar; Wilson, Robert; Seshadri, Suresh

    2007-01-01

    A proposed telescope would afford high resolution over a narrow field of view (<0.10 ) while scanning over a total field of view nominally 16 wide without need to slew the entire massive telescope structure. The telescope design enables resolution of a 1-m-wide object in a 50- km-wide area of the surface of the Earth as part of a 200-km-wide area field of view monitored from an orbit at an altitude of 700 km. The conceptual design of this telescope could also be adapted to other applications both terrestrial and extraterrestrial in which there are requirements for telescopes that afford both wide- and narrow-field capabilities. In the proposed telescope, the scanning would be effected according to a principle similar to that of the Arecibo radio telescope, in which the primary mirror is stationary with respect to the ground and a receiver is moved across the focal surface of the primary mirror. The proposed telescope would comprise (1) a large spherical primary mirror that would afford high resolution over a narrow field of view and (2) a small displaceable optical relay segment that would be pivoted about the center of an aperture stop to effect the required scanning (see figure). Taken together, both comprise a scanning narrow-angle telescope that does not require slewing the telescope structure. In normal operation, the massive telescope structure would stare at a fixed location on the ground. The inner moveable relay optic would be pivoted to scan the narrower field of view over the wider one, making it possible to retain a fixed telescope orientation, while obtaining high-resolution images over multiple target areas during an interval of 3 to 4 minutes in the intended orbit. The pivoting relay segment of the narrow-angle telescope would include refractive and reflective optical elements, including two aspherical mirrors, to counteract the spherical aberration of the primary mirror. Overall, the combination of the primary mirror and the smaller relay optic

  4. A high resolution laser ranging system based on time-correlated single-photon counting technology

    Science.gov (United States)

    Yang, Yixin; Wang, Huanqin; Huang, Zhe; Cao, Yangyang; Gui, Huaqiao

    2014-12-01

    Laser ranging has become an important method for both distance measurements and acquisition of threedimensional (3D) images. In this paper, a laser ranging system based on Time-Correlated Single-Photon Counting technology (TCSPC) is developed. A Geiger-mode avalanche photodiode (G-APD), which has the ability of detecting single-photon events, is used to capture the weak light scattered from the long-range target. In order to improve the ranging resolution of TCSPC based measurement system, a high repetition frequency of subnanosecond narrow pulse generator circuit based on the avalanche effect of RF-BJT is designed and applied as the light source. Moreover, some optimized optical light designs have been done to improve the system signal to noise rate (SNR), including using a special aspherical lens as projecting lens, adopting a telephoto camera lens with small view angle and short depth of field before detector. Experimental tests for evaluation of the laser raging system performance are described. As a means of echo signal analysis, three different algorithms have been introduced, in which the cross-correlation algorithm was demonstrated to be the most effective algorithm to determining the round trip time to a target, even based on histograms with a significant amount of background noise photons. It was found that centimeter ranging resolution can be achieved thanks to the use of Time-to-Digital Converter (TDC) with picosecond resolution and the Cross-Correlation algorithm. The proposed laser ranging system has advantages of high range resolution, short response time and simple structure, which was potential applications for 3D object recognition, computer vision, reverse engineering and virtual reality.

  5. Subaperture approaches to finishing and testing astronomical optics

    Science.gov (United States)

    Forbes, Gregory W.; Tricard, Marc

    2004-07-01

    We describe the application of both stitching interferometry and magneto-rheological finishing (MRF) to the surface metrology and final figure correction of large optics. These particular subaperture technologies help to address the need for flexible systems that improve both overall manufacturing time and cost effectiveness. MRF can achieve high volumetric removal rates with a small-footprint tool that is perfectly conformable and highly stable. This tool is therefore well suited to finishing large optics (including aspheres) and correcting mid-spatial frequency errors. The system does not need vacuum, reduces microroughness to below one nm rms on most materials, and is able to meet the figure tolerance specs for astronomical optics. Such a technology is ideally complemented by a system for the stitching of interferometric subaperture data. Stitching inherently enables the testing of larger apertures with higher resolution and, thanks to the inbuilt calibration, even to higher accuracy in many situations. Moreover, given the low-order character of the dominant residual uncertainties in the stitched full-aperture data, such an approach is well suited to adaptive mirrors because the actuators correct precisely these deformations. While this approach enables the non-null testing of parts with greater aspheric departure and can lead to a significantly reduced non-common air path in the testing of long-radius concave parts, it is especially effective for convex optics. That is, stitching is particularly well suited to the testing of secondary mirrors and, alongside the testing of the off-axis primary segments, these are clearly critical challenges for extremely large telescope (ELT) projects.

  6. 新舟700螺旋桨飞机起飞航迹的计算研究%Calculating Study of Departure Flight Path for MA700 Propeller Aircraft

    Institute of Scientific and Technical Information of China (English)

    闫国华; 刘青杰

    2015-01-01

    Aviation plays an increasingly important role in the transport sector, the number of aircraft continues to rise, but al-so brings some adverse effects like noise, etc. There are more and more research on aircraft, and calculation of the aircraft taking off track is also paid more attention. Setting the MA700 aircraft as an example, the taking off track calculation and flight path segmentation method of propeller aircraft are analyzed combining with the ANP database, and the takeoff profile path diagram and line segment track diagram are plotted. The method described in this article is of high application value for the noise evaluation of the future MA700 and MA700 derivative types.%航空在运输业领域起着越来越重要的作用,飞机数量不断攀升的同时也带来噪声等不利影响。对飞机各个方面的研究越来越多,飞机起飞航迹的计算研究也受到重视。以新舟700飞机为例,结合ANP数据库,研究螺旋桨飞机的起飞航迹计算方法和飞行航迹计算的分段法,并绘制飞机起飞剖面航迹图和分割线段航迹示意图,对未来新舟700飞机及其衍生机型的噪声评价具有重要的工程应用价值。

  7. High resolution study of the inclusive production of massive muon pairs by intense pion beams

    CERN Multimedia

    2002-01-01

    This experiment measures with high resolution and large acceptance the inclusive production of massive muon pairs with the intense pion beam (up to $10^{10} \\pi/$pulse) in the experimental hall ECN3. The experiment explores extended M$^{2}$/s, x and transverse momentum ranges. The study of the departures of the lepton-pair production cross- section from scaling constitutes a good test of QCD ideas; in the framework of the 'Drell-Yan' process, the experiment allows a detailed study of the pion parton distribution functions. The detector consists of a beam dump, a pulsed toroidal a magnet, MWPC's and scintillator hodoscopes. Its $\\sim 2$% mass resolution at 10 GeV is adequate for the substraction of resonances in the high-mass region.

  8. The corrections to scaling within Mazenko's theory in the limit of low and high dimensions

    Indian Academy of Sciences (India)

    N P Rapapa; M Fabiane

    2009-06-01

    We consider corrections to scaling within an approximate theory developed by Mazenko for nonconserved order parameter in the limit of low ( → 1) and high ( → ∞) dimensions. The corrections to scaling considered here follows from the departures of the initial condition from the scaling morphology. Including corrections to scaling, the equal time correlation function has the form: $C(r, t) = f_{0} (r/L) + L^{−} f_{1} (r/L) + \\cdots$, where is a characteristic length scale (i.e. domain size). The correction-to-scaling exponent ω and the correction-to-scaling functions 1() are calculated for both low and high dimensions. In both dimensions the value of ω is found to be ω = 4 similar to 1D Glauber model and OJK theory (the theory developed by Ohta, Jasnow and Kawasaki).

  9. Mixtures of endocrine disrupting contaminants modelled on human high end exposures

    DEFF Research Database (Denmark)

    Christiansen, Sofie; Kortenkamp, A.; Petersen, Marta Axelstad

    2012-01-01

    in vivo endocrine disrupting effects and information about human exposures was available, including phthalates, pesticides, UV‐filters, bisphenol A, parabens and the drug paracetamol. The mixture ratio was chosen to reflect high end human intakes. To make decisions about the dose levels for studies...... though each individual chemical is present at low, ineffective doses, but the effects of mixtures modelled based on human intakes have not previously been investigated. To address this issue for the first time, we selected 13 chemicals for a developmental mixture toxicity study in rats where data about...... in the rat, we employed the point of departure index (PODI) approach, which sums up ratios between estimated exposure levels and no‐observed‐adverse‐effect‐level (NOAEL) values of individual substances. For high end human exposures to the 13 selected chemicals, we calculated a PODI of 0.016. As only a PODI...

  10. Scaling of Fiber Laser Systems Based on Novel Components and High Power Capable Packaging and Joining Technologies

    Science.gov (United States)

    2010-09-01

    l ri Laser Splicing/ Welding r li i / l i Contact Bonding t t i Wafer Level Bonding Mineralic, Fusion. Anodic, Eutectic, Glass-frit, liquid...diode Bonding and Packaging of Optical Components Solder Bumping Thickfilm Au Metallization Laser diode Fiber Assembly element Asphere Ceramic System

  11. Al2O3/H2O 纳米流体球形下封头表面气泡脱离行为模拟%Simulation on Bubble Departure Behavior of Al2 O3/H2 O Nanofluid on Lower Head Outer Surface

    Institute of Scientific and Technical Information of China (English)

    王云; 武俊梅

    2016-01-01

    压力容器内滞留(IVR)策略可在反应堆发生严重事故后,有效地将堆内熔融物滞留在压力容器内,是防止放射性物质外泄的关键技术。纳米流体是将粒径小于100nm的固体颗粒加入到基液中以提高换热特性的稳定悬浮液,其热物性以及换热特性与传统固液悬浮液相比有较大区别,适宜的纳米流体种类及配比可强化换热。本文采用引入了无网格对流格式的移动粒子半隐法(MPS方法)研究了体积份额为1.0%的Al2O3/H2O纳米流体和纯水中加热面朝下时气泡在加热面上的成长、脱离以及附着形成气膜的过程,探索了气泡脱离的临界角度及其影响因素,为加速纳米流体的工业应用、增强IVR能力提供理论基础。%The in‐vessel retention (IVR) strategy is a key technology to retain the core melt in reactor vessel and prevent the leakage of radioactive material after severe acci‐dent happened to the nuclear reactor .The nanofluid is a fluid with steady suspension of solid nanoparticles ,in w hich solid particles with diameters below 100 nm are added to base fluid to improve heat transfer characteristics of working fluids .Its thermal physical properties and heat transfer characteristics are much different from the conventional sol‐id particle suspended working fluid .Thus ,the nanofluid with appropriate nanoparticle type and volumetric concentration can enhance heat transfer .In this study ,the M PS‐MAFL (moving particle semi‐implicit method‐meshless advection using flow‐directional local grid) method was used to simulate the growth ,departure and attaching and gas film forming of the bubble on the downward‐facing heating surface in pure water and nanofluid (volume fraction is 1.0% Al2O3/H2O) flow process .The critical departure angle of bubble and its influence factors were studied .This research work lays the theo‐retical foundation of enhancing IVR capacity and accelerating

  12. 小微企业不需要担保公司担保吗?--小微信贷与融资性担保背离的内在逻辑%Is Guarantee Corporation not Needed for Micro Businesses:the Internal Logic of Departure Between Micro Businesses Credit and Financing Guarantee

    Institute of Scientific and Technical Information of China (English)

    户兴磊

    2015-01-01

    Guarantee mechanism is the effective way to solve the problem of micro businesses credit financing, but micro businesses credit and financing guarantee has shown a departure from the development trend. The main rea-sons include commercial banks' rigid payment preferences, inappropriate risk-sharing between bank and guarantee, the guarantee corporation's rigid anti-guarantee measures,and the business mode of large risk, less profit. In order to achieve the sustainable development of the financing guarantee, besides breaking the rigid mechanism of commercial banks and guarantee corporation,the more important is that the guarantee corporation should explore the new“equity+guarantee”model to solve the large risk,less profit problem effectively.%融资担保机制是小微企业融资增信的有效途径,但小微企业信贷与融资性担保业务却呈现背离的发展态势。研究发现,商业银行对贷款的刚性兑付偏好、银担风险分担机制不健全、担保公司的刚性反担保措施和风险收益不对等的业务模式是主要原因。要实现融资担保行业的可持续发展,除需打破商业银行和担保公司刚性的风险管控机制以外,更重要的是担保机构要积极探索“股权+担保权”联动等业务模式,有效解决担保机构风险和收益不对等问题。

  13. Departure time influences foraging associations in little penguins.

    Science.gov (United States)

    Sutton, Grace J; Hoskins, Andrew J; Berlincourt, Maud; Arnould, John P Y

    2017-01-01

    Recent studies have documented that little penguins (Eudyptula minor) associate at sea, displaying synchronised diving behaviour throughout a foraging trip. However, previous observations were limited to a single foraging trip where only a small number of individuals were simultaneously tracked. Consequently, it is not known whether coordinated behaviour is consistent over time, or what factors influence it. In the present study, breeding adults were concurrently instrumented with GPS and dive behaviour data loggers for at least 2 consecutive foraging trips during guard and post-guard stage at two breeding colonies (London Bridge and Gabo Island, south-eastern Australia) of contrasting population size (approximately 100 and 30,000-40,000, respectively). At both colonies, individuals were sampled in areas of comparable nesting density and spatial area. At London Bridge, where individuals use a short (23 m) common pathway from their nests to the shoreline, > 90% (n = 42) of birds displayed foraging associations and 53-60% (n = 20) maintained temporally consistent associations with the same conspecifics. Neither intrinsic (sex, size or body condition) nor extrinsic (nest proximity) factors were found to influence foraging associations. However, individuals that departed from the colony at a similar time were more likely to associate during a foraging trip. At Gabo Island, where individuals use a longer (116 m) pathway with numerous tributaries to reach the shoreline, few individuals (< 31%; n = 13) from neighbouring nests associated at sea and only 1% (n = 1) maintained associations over subsequent trips. However, data from animal-borne video cameras indicated individuals at this colony displayed foraging associations of similar group size to those at London Bridge. This study reveals that group foraging behaviour occurs at multiple colonies and the pathways these individuals traverse with conspecifics may facilitate opportunistic group formation and resulting in foraging associations irrespective of nesting proximity and other factors.

  14. Evaluation of Pre-Departure English Training Program

    Directory of Open Access Journals (Sweden)

    Ali Saukah

    2016-02-01

    Full Text Available The program evaluation reported in this article covers three batches of participants, from 1996 through 1997, sponsored by the Directorate General of Higher Education projects to prepare faculty members of teacher training institutions for overseas studies. The result outcomes could be achieved when the initial English competence requirred for participating in the program was at least at the Pre-Advanced level. The criterion validity of the TOEFL-Equivalent test developed by the program was assured, and the test could, therefore, be used as a good predictor of the International TOEFL. Other recommendations are also given for the improvement of the planning and implementation of the program in the future

  15. [Morphological points of departure for the therapy of rheumatic diseases].

    Science.gov (United States)

    Fassbender, H G

    1975-01-01

    Pathogenic mechanisms of several rheumatic diseases are reported. Besides signs of nonspecific inflammation there are characteristic features in some rheumatic disorders: in rheumatoid arthritis one can find mesenchymoid proliferation and - in seropositive cases only - necrosis ot tissue. In ankylosing spondylitis osseous metaplasia of the intervertebral discs, in psoriatic arthritis, osteoclastic and in osteoblastic changes without inflammation. In fibrositis syndrome, however, there was no evidence of inflammation, but one may detect local muscular lesions and proliferation of fibroblasts. Pain in osteoarthritis is always caused by secondary inflammation. Due to this data, the possibilities of treatment are discussed, especially those of nonsteroidal drugs.

  16. Modelling Packet Departure Times using a Known PDF

    Directory of Open Access Journals (Sweden)

    Stanislav Klucik

    2014-01-01

    Full Text Available This paper deals with IPTV traffic source modelling and describes a packet generator based on a known probability density function which is measured and formed from a histogram. Histogram based probability density functions destroy an amount of information, because classes used to form the histogram often cover significantly more events than one. In this work, we propose an algorithm to generate far more output states of random variable X than the input probability distribution function is made from. In this generator is assumed that all IPTV packets of the same video stream are the same length. Therefore, only packet times are generated. These times are generated using the measured normalized histogram that is converted to a cumulative distribution function which acts as a finite number of states that can be addressed. To address these states we use an ON/OFF model that is driven by an uniform random number generator in (0, 1. When a state is chosen then the resulting value is equal to a histogram class. To raise the number of possible output states of the random variable X, we propose to use an uniform random number generator that generates numbers within the range of the chosen histogram class. This second uniform random number generator assures that the number of output states is far more larger than the number of histogram classes.

  17. Departures from Axisymmetric Balance Dynamics during Secondary Eyewall Formation

    Science.gov (United States)

    2014-10-01

    arguments, based mostly on linearized Ekman theory, to propose a feedback mechanism for secondary eye- wall formation that involves a local enhancement of...the radial vorticity gradient, frictional updraft, and con- vection. The hypothesized feedback, based primarily on linear Ekman balance reasoning, has...largely to a vertical column within an annular region about 15 km wide, centered around 40 km and sloping outward. The mean heating rate maximum exhibits a

  18. Quantized biopolymer translocation through nanopores: departure from simple scaling

    CERN Document Server

    Melchionna, Simone; Fyta, Maria; Kaxiras, Efthimios; Succi, Sauro

    2009-01-01

    We discuss multiscale simulations of long biopolymer translocation through wide nanopores that can accommodate multiple polymer strands. The simulations provide clear evidence of folding quantization, namely, the translocation proceeds through multi-folded configurations characterized by a well-defined integer number of folds. As a consequence, the translocation time acquires a dependence on the average folding number, which results in a deviation from the single-exponent power-law characterizing single-file translocation through narrow pores. The mechanism of folding quantization allows polymers above a threshold length (approximately $1,000$ persistence lengths for double-stranded DNA) to exhibit cooperative behavior and as a result to translocate noticeably faster.

  19. New Probe of Departures from General Relativity Using Minkowski Functionals.

    Science.gov (United States)

    Fang, Wenjuan; Li, Baojiu; Zhao, Gong-Bo

    2017-05-05

    The morphological properties of the large scale structure of the Universe can be fully described by four Minkowski functionals (MFs), which provide important complementary information to other statistical observables such as the widely used 2-point statistics in configuration and Fourier spaces. In this work, for the first time, we present the differences in the morphology of the large scale structure caused by modifications to general relativity (to address the cosmic acceleration problem), by measuring the MFs from N-body simulations of modified gravity and general relativity. We find strong statistical power when using the MFs to constrain modified theories of gravity: with a galaxy survey that has survey volume ∼0.125(h^{-1}  Gpc)^{3} and galaxy number density ∼1/(h^{-1}  Mpc)^{3}, the two normal-branch Dvali-Gabadadze-Porrati models and the F5 f(R) model that we simulated can be discriminated from the ΛCDM model at a significance level ≳5σ with an individual MF measurement. Therefore, the MF of the large scale structure is potentially a powerful probe of gravity, and its application to real data deserves active exploration.

  20. Analysis of C-17 Departure Reliability and Maintenance Metrics

    Science.gov (United States)

    2010-06-01

    regression output ....................................................................... 32 Figure 17: VIF output...32 Table 6: VIF guidelines...variance inflation factor ( VIF ) from the best model equation of the forward selection procedure is evaluated. VIF indicates the extent to which

  1. Departure Ceremony for Chinese International Friendship Volunteers Held in Beijing

    Institute of Scientific and Technical Information of China (English)

    An; Xin

    2013-01-01

    <正>The CPAFFC launched the"Program of Chinese International Friendship Volunteers"in 2012.On July 18 this year,it joined with the Program’s organizer,Zhongxie Human Resource Consulting Center(Zhongxie HR),to

  2. Socio-rhetorical interpretation: Theoretical points of departure

    Directory of Open Access Journals (Sweden)

    Ernest van Eck

    2001-01-01

    Full Text Available In the past two decades, narrative criticism (narratology and social-scientific criticism have come to the fore as the two most prominent new methodologies to be associated with gospel research. When these two methodologies are integrated in the reading of biblical texts, this is now referred to as "socio-rhetorical interpretation". This article departs from a specific understanding of what is meant by a narratological reading of a text on the one hand and, on the other hand, by a social-scientific interpretation of biblical texts, in order to propose a working definition of a socio-rhetorical analysis of texts.

  3. Departures from optimality when pursuing multiple approach or avoidance goals.

    Science.gov (United States)

    Ballard, Timothy; Yeo, Gillian; Neal, Andrew; Farrell, Simon

    2016-07-01

    This article examines how people depart from optimality during multiple-goal pursuit. The authors operationalized optimality using dynamic programming, which is a mathematical model used to calculate expected value in multistage decisions. Drawing on prospect theory, they predicted that people are risk-averse when pursuing approach goals and are therefore more likely to prioritize the goal in the best position than the dynamic programming model suggests is optimal. The authors predicted that people are risk-seeking when pursuing avoidance goals and are therefore more likely to prioritize the goal in the worst position than is optimal. These predictions were supported by results from an experimental paradigm in which participants made a series of prioritization decisions while pursuing either 2 approach or 2 avoidance goals. This research demonstrates the usefulness of using decision-making theories and normative models to understand multiple-goal pursuit. (PsycINFO Database Record

  4. 47 CFR 73.1545 - Carrier frequency departure tolerances.

    Science.gov (United States)

    2010-10-01

    ... carrier offset, including those stations licensed with a maximum effective radiated power and/or antenna... offset. See Memorandum Opinion and Order on Reconsideration, In the Matter of Establishment of a Class...

  5. Predicting the Timing of Women's Departure from Abusive Relationships

    Science.gov (United States)

    Panchanadeswaran, Subadra; McCloskey, Laura A.

    2007-01-01

    The aim of this study was to investigate forces that affect the timing of women's exit from violent relationships with men. Abused women were recruited from posters in the community and battered women's shelters, interviewed, and followed up for 10 years. Data for this study are based on 100 women and were analyzed using event history analysis.…

  6. Developments and departures in the philosophy of soil science

    Science.gov (United States)

    Traditional soil science curriculums provide comprehensive instruction on soil properties, soil classification, and the physical, chemical, and biological processes that occur in soils. This reductionist perspective is sometimes balanced with a more holistic perspective that focuses on soils as natu...

  7. Departures From Axisymmetric Morphology and Dynamics in Spiral Galaxies

    CERN Document Server

    Kornreich, D A; Lovelace, R V E; Van Zee, L; Kornreich, David A.; Haynes, Martha P.; Zee, Liese van

    2000-01-01

    New HI synthesis data have been obtained for six face-on galaxies with the Very Large Array. These data and reanalyses of three additional data sets make up a sample of nine face-on galaxies analyzed for deviations from axisymmetry in morphology and dynamics. This sample represents a subsample of galaxies already analyzed for morphological symmetry properties in the R-band. Four quantitative measures of dynamical nonaxisymmetry are compared to one another and to the quantitative measures of morphological asymmetry in HI and R-band to investigate the relationships between nonaxisymmetric morphology and dynamics. We find no significant relationship between asymmetric morphology and most of the dynamical measures in our sample. A possible relationship is found, however, between morphology and dynamical position angle differences between approaching and receding sides of the galaxy.

  8. Robust Lane Sensing and Departure Warning under Shadows and Occlusions

    Directory of Open Access Journals (Sweden)

    Miguel Torres-Torriti

    2013-03-01

    Full Text Available A prerequisite for any system that enhances drivers’ awareness of road conditions and threatening situations is the correct sensing of the road geometry and the vehicle’s relative pose with respect to the lane despite shadows and occlusions. In this paper we propose an approach for lane segmentation and tracking that is robust to varying shadows and occlusions. The approach involves color-based clustering, the use of MSAC for outlier removal and curvature estimation, and also the tracking of lane boundaries. Lane boundaries are modeled as planar curves residing in 3D-space using an inverse perspective mapping, instead of the traditional tracking of lanes in the image space, i.e., the segmented lane boundary points are 3D points in a coordinate frame fixed to the vehicle that have a depth component and belong to a plane tangent to the vehicle’s wheels, rather than 2D points in the image space without depth information. The measurement noise and disturbances due to vehicle vibrations are reduced using an extended Kalman filter that involves a 6-DOF motion model for the vehicle, as well as measurements about the road’s banking and slope angles. Additional contributions of the paper include: (i the comparison of textural features obtained from a bank of Gabor filters and from a GMRF model; and (ii the experimental validation of the quadratic and cubic approximations to the clothoid model for the lane boundaries. The results show that the proposed approach performs better than the traditional gradient-based approach under different levels of difficulty caused by shadows and occlusions.

  9. Creativity, Group Pedagogy and Social Action: A Departure from Gough

    Science.gov (United States)

    Evans, James; Cook, Ian; Griffiths, Helen

    2008-01-01

    The following paper continues discussions within this journal about how the work of Delueze and Guattari can inform radical pedagogy. Building primarily on Noel Gough's 2004 paper, we take up the challenge to move towards a more creative form of "becoming cyborg" in our teaching. In contrast to work that has focused on Deleuzian theories of the…

  10. TEACHERS’ STRATEGY IN IMPLEMENTING ENGLISH CURRICULUM IN A JUNIOR HIGH SCHOOL IN INDONESIA

    Directory of Open Access Journals (Sweden)

    Raden Intansari

    2013-01-01

    Full Text Available Abstract: This study is a part of a bigger study investigating teachers’ personal theories (beliefs regarding English teaching and learning. Involving forty-two English teachers of fifteen Junior High Schools in the city of Sukabumi, West Java, this cross-sectional survey study used data gained from an open-ended questionnaire. A total of 3696 raw data items were gathered and analyzed both qualitatively and quantitatively. Relevant findings regarding the implementation of the curriculum in the daily process of English teaching and learning show that there are gaps between the mandated curriculum as stipulated by the government and the implemented curriculum at the classroom level. This departure from the mandated curriculum, in turn, diverts the course of curriculum implementation and leads to a level of accomplishment of the main goals of the English teaching and learning, which is different from what is stated in the mandated curriculum.

  11. The Effects of Drag and Tidal Forces on the Orbits of High-Velocity Clouds

    Science.gov (United States)

    Fernandes, Alexandre; Benjamin, R. A.

    2013-06-01

    Over the past several years, orbital constraints have been obtained for several high velocity cloud complexes surrounding the Milky Way: Complex GCP (Smith Cloud), Complex A, Complex H, Complex GCN, and the Magellanic Stream. We summarize what is known about the orbits of these clouds and and discuss how well each of these complexes fits a balistic trajectory, and discuss how the length of a complex across the sky is related to the inital "fragmentation" and velocity dispersion of the clouds. We then introduce gas drag into the simulation of the orbits of these complexes. We present analytical tests of our numerical method and characterize the departure of the clouds from the ballistic trajectory as a function of drag parameters (ambient gas density and velocity and cloud column density). Using the results of these simulations we comment on the survivability and ultimate fate of HVC in the context of the different models of drag forces.

  12. A Fast and High-Resolution Multi-Target Localization Approach in MIMO Radar

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2013-09-01

    Full Text Available This paper presents a fast and high-resolution estimation approach using polarization information combined with angle information for multi-target localization in bistatic multiple-input multiple-output (MIMO radar. The propagator method (PM is extended to jointly estimate the direction of departure (DOD, the direction of arrival (DOA and the polarization parameters. The PM avoids the singular value decomposition (SVD of the covariance matrix of the received signals so that the computational complexity is reduced. In addition, the closely spaced targets can be well distinguished by polarization diversity. The Cramer-Rao bounds (CRBs of the estimated parameters are derived. The position of a target is calculated based on the estimated angles. The simulation results demonstrate that the proposed approach can achieve better performance compared with conventional methods of target localization.

  13. Preliminary C3 Loading Analysis for Future High-Altitude Unmanned Aircraft in the NAS

    Science.gov (United States)

    Ho, Yan-Shek; Gheorghisor, Izabela; Box, Frank

    2006-01-01

    This document provides a preliminary assessment and summary of the command, control, and communications (C(sup 3)) loading requirements of a generic future high-altitude, long-endurance unmanned aircraft (UA) operating at in the National Airspace System. Two principal types of C(sup 3) traffic are considered in our analysis: communications links providing air traffic services (ATS) to the UA and its human pilot, and the command and control data links enabling the pilot to operate the UA remotely. we have quantified the loading requirements of both types of traffic for two different assumed levels of UA autonomy. Our results indicate that the potential use of UA-borne relays for the ATS links, and the degree of autonomy exercised by the UA during the departure and arrival phases of its flight, will be among the key drivers of C(sup 3) loading and bandwidth requirements.

  14. Retention of Highly Skilled Workers in Science and Technology: Distant Regional Employers’ Point of View

    Directory of Open Access Journals (Sweden)

    Catherine Beaudry

    2014-05-01

    Full Text Available This exploratory research focuses on the retention of highly skilled workers in science and technology (HSWST in the distant regions of Canada.  Indeed, the human resource shortage forces them to seek more stability in their employment relationships. Our first objective is to analyze the point of view of distant regional employers regarding their retention capacity of HSWST and the reasons behind voluntary turnover in this group of workers. Our second objective is to analyze the retention strategies and practices implemented by these employers. This study uses a qualitative approach, which is to say the case study of businesses hiring HSWST in the Lower St. Lawrence Region of Canada. Results show that employers generally think they have good retention capacity. Employers believe that departures are chiefly due to personal reasons or working conditions. In addition, employers generally have no formal or planned strategies or practices with respect to retention.

  15. Highly super-Chandrasekhar white dwarfs in an extensive GRMHD framework

    CERN Document Server

    Das, Upasana

    2016-01-01

    Our consistent effort to unravel the mystery of super-Chandrasekhar white dwarfs (WDs), by exploiting the potential of magnetic fields, has brought this topic considerable attention. This is also evident from the recent surge in the corresponding literature. In the present work, by means of full-scale general relativistic magnetohydrodynamic (GRMHD) numerical analysis, we confirm the existence of stable, highly magnetized, significantly super-Chandrasekhar WDs having mass exceeding 3 solar mass. We have explored various possible field configurations, namely, poloidal, toroidal and mixed, by self-consistently incorporating the departure from spherical symmetry induced by a strong magnetic field. Such super-Chandrasekhar WDs can be ideal progenitors of peculiar, over-luminous type Ia supernovae.

  16. Strain and High Temperature Superconductivity: Unexpected Results from Direct Electronic Structure Measurements in Thin Films

    Science.gov (United States)

    Abrecht, M.; Ariosa, D.; Cloetta, D.; Mitrovic, S.; Onellion, M.; Xi, X.; Margaritondo, G.; Pavuna, D.

    2003-07-01

    Angle-resolved photoemission spectroscopy reveals very surprising strain-induced effects on the electronic band dispersion of epitaxial La2-xSrxCuO4-δ thin films. In strained films we measure a band that crosses the Fermi level (EF) well before the Brillouin zone boundary. This is in contrast to the flat band reported in unstrained single crystals and in our unstrained films, as well as in contrast to the band flattening predicted by band structure calculations for in-plane compressive strain. In spite of the density of states reduction near EF, the critical temperature increases in strained films with respect to unstrained samples. These results require a radical departure from commonly accepted notions about strain effects on high temperature superconductors, with possible general repercussions on superconductivity theory.

  17. High-speed Bullet Ejections during the AGB-to-Planetary Nebula Transition: HST Observations of the Carbon Star, V Hydrae

    Science.gov (United States)

    Sahai, R.; Scibelli, S.; Morris, M. R.

    2016-08-01

    The well-studied carbon star, V Hya, showing evidence for high-speed, collimated outflows and dense equatorial structures, is a key object in the study of the poorly understood transition of AGB stars into aspherical planetary nebulae. Using the Space Telescope Imaging Spectrograph instrument on board the Hubble Space Telescope, we have obtained high spatial-resolution long-slit optical spectra of V Hya that show high-velocity emission in [S ii] and [Fe ii] lines. Our data set, spanning three epochs spaced apart by a year during each of two periods (in 2002-2004 and 2011-2013), shows that V Hya ejects high-speed (˜200-250 {km} {{{s}}}-1) bullets once every ˜8.5 years. The ejection axis flip-flops around a roughly eastern direction, both in and perpendicular to the sky-plane, and the radial velocities of the ejecta also vary in concert between low and high values. We propose a model in which the bullet ejection is associated with the periastron passage of a binary companion in an eccentric orbit around V Hya with an orbital period of ˜8.5 years. The flip-flop phenomenon is likely the result of collimated ejection from an accretion disk (produced by gravitational capture of material from the primary) that is warped and precessing, and/or that has a magnetic field that is misaligned with that of the companion or the primary star. We show how a previously observed 17 year period in V Hya’s light-cycle can also be explained in our model. Additionally, we describe how the model proposed here can be extended to account for multipolar nebulae.

  18. Focal plane actuation to achieve ultra-high resolution on suborbital balloon payloads

    Science.gov (United States)

    Scowen, Paul A.; Miller, Alex; Challa, Priya; Veach, Todd; Groppi, Chris; Mauskopf, Phil

    2014-07-01

    Over the past few years there has been remarkable success flying imaging telescope systems suspended from suborbital balloon payload systems. These imaging systems have covered optical, ultraviolet, sub-­-millimeter and infrared passbands (i.e. BLAST, STO, SBI, Fireball and others). In recognition of these advances NASA is now considering ambitious programs to promote planetary imaging from high altitude at a fraction of the cost of similar fully orbital systems. The challenge with imaging from a balloon payload is delivering the full diffraction-­-limited resolution of the system from a moving payload. Good progress has been made with damping mechanisms and oscillation control to remove most macroscopic movement in the departures of the imaging focal plane from a static configuration, however a jitter component remains that is difficult to remove using external corrections. This paper reports on work to demonstrate in the laboratory the utility and performance of actuating a detector focal plane (of whatever type) to remove the final jitter terms using an agile hexapod design. The input to this demonstration is the jitter signal generated by the pointing system of a previously flown balloon mission (the Stratospheric Terahertz Observatory, STO). Our group has a mature jitter compensation system that thermally isolates the control head from the focal plane itself. This allows the hexapod to remain at ambient temperature in a vacuum environment with the focal plane cooled to cryogenic temperatures. Our lab design mounts the focal plane on the hexapod in a custom cryostat and delivers an active optical stimulus together with the corresponding jitter signal, using the actuation of the hexapod to correct for the departures from a static, stable configuration. We believe this demonstration will make the case for inclusion of this technological solution in future balloon-­-borne imaging systems requiring ultra-­-high resolution.

  19. Beach week: a high school graduation rite of passage for sun, sand, suds, and sex.

    Science.gov (United States)

    Schwartz, R H; Milteer, R; Sheridan, M J; Horner, C P

    1999-02-01

    Every year, thousands of suburban high school graduates from mid Atlantic states flock to nearby coastal beaches for a long-anticipated rite of passage known as "beach week." Sand, sun, and sea, and also smoking, binge drinking, drugs, and sex, are reported to be dominant themes. To document risk-taking behaviors by girls during beach week. Fifty-nine female suburban high school graduates who attended beach week in 1996 volunteered to fill out a confidential printed survey. Twenty-five girls (42%) completed the survey during a typical beach week party. Their activities were verified on site by a peer, recommended by her grade advisor for her integrity and popularity. Breath alcohol values were obtained at entry and departure from the party. The remaining 34 girls completed the supervised survey 2 to 3 months later. Daily cigarette smoking (54%), daily drunkenness (75%), and sex (46%) were the norm among respondents of our survey. Few reported first-time sex (n = 4) or drug use (n = 2). Abstinence from drugs (67%) and sex (55%) was not unusual but only 12% abstained from getting drunk. Sixteen girls (64%) reported that they drank 8 or more beers/wine during a typical beach week party. By departure from the party, 15 girls had breath alcohol values of 0.017 mmol/L or greater (reference range, <21.7 mmol/L), and 8 additional girls had breath alcohol values of 0.01 mmol/L to 0.015 mmol/L. Fifteen percent of the 59 reported injuries or illness were related to alcohol or drugs. Most respondents enjoyed beach week but a large percentage engaged in serious risk-taking behaviors.

  20. An un-obscured four spherical mirrors based" collimator as a tradeoff solution for the Optical Ground Support Equipment (OGSE) of the High Resolution Camera (HRIC) of Simbio-Sys

    Science.gov (United States)

    Barilli, M.; Bartoli, A.; Dami, M.; Flamini, E.; Formaro, R.; Grifoni, F.; Longo, F.; Pompei, C.

    2012-09-01

    The authors present the tradeoff and the merit criteria that lead to the selection of the M. Brunn [1] "un obscured four mirrors based telescope" as the collimator of the Optical Ground Support Equipment in the frame of the Assembly Integration and Verification (AIV) activities forecast for the optical characterization of the High Resolution Camera (HRIC) on board of the Simbio-sys mission to Mercury, instrument currently under development and manufacturing at Selex Galileo (SG) facilities in its Florence site. Several optical configurations have been accounted for the design and manufacturing of the three meters focal length, diffraction limited and wide field of view (0.4X0.6 degs) toolkit. From the classical un obscured systems such as the aspheric solution based onto two hyperbolic mirror, working under an f - number of 13.6, the Brunn solution revealed excellent optical quality free from coma, astigmatism and spherical aberration accomplished by an ultra compact design in within a volume of 1.2x1.0 x0.5 cubic meters and other basic advantages such as the relative easy way in aligning and manufacturing the mirrors.

  1. Software system design for the non-null digital Moiré interferometer

    Science.gov (United States)

    Chen, Meng; Hao, Qun; Hu, Yao; Wang, Shaopu; Li, Tengfei; Li, Lin

    2016-11-01

    Aspheric optical components are an indispensable part of modern optics systems. With the development of aspheric optical elements fabrication technique, high-precision figure error test method of aspheric surfaces is a quite urgent issue now. We proposed a digital Moiré interferometer technique (DMIT) based on partial compensation principle for aspheric and freeform surface measurement. Different from traditional interferometer, DMIT consists of a real and a virtual interferometer. The virtual interferometer is simulated with Zemax software to perform phase-shifting and alignment. We can get the results by a series of calculation with the real interferogram and virtual interferograms generated by computer. DMIT requires a specific, reliable software system to ensure its normal work. Image acquisition and data processing are two important parts in this system. And it is also a challenge to realize the connection between the real and virtual interferometer. In this paper, we present a software system design for DMIT with friendly user interface and robust data processing features, enabling us to acquire the figure error of the measured asphere. We choose Visual C++ as the software development platform and control the ideal interferometer by using hybrid programming with Zemax. After image acquisition and data transmission, the system calls image processing algorithms written with Matlab to calculate the figure error of the measured asphere. We test the software system experimentally. In the experiment, we realize the measurement of an aspheric surface and prove the feasibility of the software system.

  2. Wagon-flow Allocation Optimization of Stage Plan at Marshaling Station in Consideration of Different Size Limitations of Departure Trains%考虑不同满轴约束的编组站阶段计划配流优化

    Institute of Scientific and Technical Information of China (English)

    黎浩东; 何世伟; 景云; 王烁

    2012-01-01

    基于阶段计划列车解编顺序优化,同时考虑出发列车牵引质量及换长两个满轴约束,以车流接续与分配的“代价”最小为目标,构建编组站配流优化0-1整数规划模型,并设计与ILOG优化软件结合的和声搜索算法进行求解.其中配流结果使用ILOG求解,列车解编顺序则采用和声搜索策略进行优化.在构造新的和声过程中,采用邻域搜索策略提升算法的寻优效率.算例结果表明:提出的方法能获取鲁棒性更高的配流方案.%Taking into account the size limitations of both weight and length of departure trains, and the breakup sequence of inbound trains and make-up sequence of outbound trains, the 0-1 integer programming model for optimization of wagon-flow allocation at marshaling stations was established. The objective of this model was set to minimize the total costs of cars assignment. Then the hybrid heuristic algorithm based on the harmony search strategy and ILOG was designed to solve the model. The harmony search strategy was used to optimize the break-up sequence of inbound trains and make-up sequence of outbound trains, and cars assignment for harmonic evaluation was solved by ILOG. The neighborhood search strategy was used to enhance the convergence rate of the algorithm in the process of constructing the new harmony. The result of a numerical example proves that the proposed model and algorithm can provide a wagon-flow allocation scheme of higher robustness.

  3. Biodigestão anaeróbia de dejetos de suínos sob efeito de três temperaturas e dois níveis de agitação do substrato: considerações sobre a partida Anaerobic digestion of swine wastes under effect of three temperatures and two substratum agitation levels: considerations about the departure phase

    Directory of Open Access Journals (Sweden)

    Cecília F. Souza

    2005-08-01

    Full Text Available Neste trabalho, avaliou-se a biodigestão anaeróbia de dejetos de suínos. Para isso, foi utilizado esquema laboratorial, constituído de 24 digestores com volume total de 14 L, sendo cada um abastecido com dejetos de suínos em fase de terminação, diluídos em água, perfazendo 10 L de volume útil de substrato com concentração inicial de sólidos totais de 6%. Três grupos formados por oito desses biodigestores foram expostos a três temperaturas (25; 35 e 40 ºC e a dois níveis de agitação (com e sem do substrato. A análise da fase de partida foi feita com base na produção média acumulada de biogás, num período de 71 dias. Os resultados demonstraram que a agitação não interferiu e que o melhor desempenho, inclusive o menor tempo gasto para atingir determinado nível de produção de biogás, foi verificado na temperatura de 35 ºC.In this work was evaluated the anaerobic digestion of swine wastes. For that, a laboratory scheme was used, consisting of 24 digesters whose total volume was 14 L, being each one supplied with ending swine wastes, diluted in water, resulting on 10 L of net volume of substratum, with initial total solids concentration of 6%. Three groups formed by eight of these biodigesters were exposed to three temperatures (25; 35 and 40 ºC and to two substratum agitation levels (with and without. The departure phase analysis was based in the average accumulated biogas yield along the period of 71 days. Results showed that agitation didn't contribute and that the best performance, including the minor time requested to obtain a specific biogas yield level, was verified in the temperature of 35 ºC.

  4. Diamond Turned Super Alloy Mandrel for Slump Forming X-Ray Observatory (IXO) Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Diamond turning is proven to be able to quickly produce highly aspheric grazing incidence optical contours to visible wavelength tolerances with extremely smooth...

  5. High arch

    Science.gov (United States)

    Pes cavus; High foot arch ... High foot arches are much less common than flat feet. They are more likely to be caused ... difficult to fit into shoes. People who have high arches most often need foot support. A high ...

  6. Unusually High Nitrate Concentrations in Some Midwest United States Streams in 2013 Following the 2012 Drought

    Science.gov (United States)

    Mahler, B. J.; Van Metre, P. C.; Frey, J. W.; Musgrove, M.; Nakagaki, N.; Qi, S.; Wieczorek, M.

    2015-12-01

    Nitrogen sources in the Mississippi River basin have been linked to degradation of stream ecology and to Gulf of Mexico hypoxia. In 2013, the U.S. Geological Survey and the U.S. Environmental Protection Agency characterized water-quality stressors and ecological conditions in 100 wadeable streams across the Midwestern United States. Relatively wet conditions (2013) followed a severe drought (2012); this dry-wet pattern has been shown to be associated with elevated nitrogen concentrations and loads in streams. Nitrate concentrations during the May to August 2013 sampling period ranged from <0.04 mg L-1 to 41.8 mg L-1 as N, with a mean of 5.31 mg L-1. The highest concentrations were in Iowa and Minnesota (means of 14.4 and 10.2 mg L-1, respectively). Nitrate concentration departure from normal was positively correlated to the 2013-2012 antecedent precipitation index, a measure of the departure from normal precipitation. Correlations to watershed characteristics and nitrogen and oxygen isotopes of nitrate indicate that inorganic fertilizer and manure use in crop production, principally corn, were the dominant sources of nitrate. The anomalously high nitrate levels in parts of the Midwest in 2013 coincided with reported higher-than-normal nitrate loads in the Mississippi River. Because forecasts of future climate indicate that more frequent floods and droughts are likely in the Midwest, nitrate anomalies such as those measured in response to the dry-wet pattern in 2012 and 2013 could become more frequent.

  7. Interferometry using binary holograms without high order diffraction effects.

    Science.gov (United States)

    Boruah, Bosanta R; Love, Gordon D; Neil, Mark A A

    2011-06-15

    We describe a technique for a phase-stepping interferometer based on programmable binary phase holograms, particularly useful for optical testing of aspheric or free-form surfaces. It is well-known that binary holograms can be used to generate reference surfaces for interferometry, but a major problem is that cross talk from higher diffraction orders and aliasing can reduce the fidelity of the system. Here, we propose a new encoding technique which improves the accuracy of the technique and demonstrate its implementation using a binary liquid crystal spatial light modulator.

  8. Next Generation Space Interconnect Standard (NGSIS): a modular open standards approach for high performance interconnects for space

    Science.gov (United States)

    Collier, Charles Patrick

    2017-04-01

    The Next Generation Space Interconnect Standard (NGSIS) effort is a Government-Industry collaboration effort to define a set of standards for interconnects between space system components with the goal of cost effectively removing bandwidth as a constraint for future space systems. The NGSIS team has selected the ANSI/VITA 65 OpenVPXTM standard family for the physical baseline. The RapidIO protocol has been selected as the basis for the digital data transport. The NGSIS standards are developed to provide sufficient flexibility to enable users to implement a variety of system configurations, while meeting goals for interoperability and robustness for space. The NGSIS approach and effort represents a radical departure from past approaches to achieve a Modular Open System Architecture (MOSA) for space systems and serves as an exemplar for the civil, commercial, and military Space communities as well as a broader high reliability terrestrial market.

  9. Minimisation of the thermal load of the ablation in high-speed laser corneal refractive surgery: the 'intelligent thermal effect control' of the AMARIS platform

    Science.gov (United States)

    Brunsmann, Ulrich; Sauer, Udo; Dressler, Katharina; Triefenbach, Nico; Arba Mosquera, Samuel

    2010-03-01

    The purpose of this work was to evaluate the extent that minimisation of the thermal load of the ablation in high-speed laser corneal refractive surgery is possible. To do this, thermal load from ablations onto flat PMMA plates was recorded with an infrared thermal camera and analysed for different flying-spot sorting algorithms (from pure randomised to 36 Hz local frequency) using a 500 Hz laser system with a fluence of 500 mJ/cm2, and aspheric ablation profiles. Each ablation configuration was repeated three times. Thermal load valid for corneal ablations was modelled based upon the results from ablations onto flat PMMA plates. It was found that the thermal load of ablations onto flat PMMA plates declines steadily when the allowed local frequency decreases or when the diameter of the blocked area increases. With this laser system, a local frequency of 39 Hz dynamically controlled over a diameter of 3.865 mm seems to be optimal for avoiding corneal collagen denaturation with minimum compromise on treatment duration. Peak temperature changes of 48°C in PMMA (16°C equivalent cornea) using pure randomised flying-spot sorting algorithms were reduced to 27°C in PMMA (9°C equivalent cornea) using 36 Hz local frequency over a blocked diameter of 4.25 mm. Average temperature changes of 15°C in PMMA (5°C equivalent cornea) using pure randomised flying-spot sorting algorithms were reduced to 7°C in PMMA (2°C equivalent cornea) using 36 Hz local frequency over a blocked diameter of 4.25 mm. Hence, minimisation of the thermal load of the ablation in high-speed laser corneal refractive surgery seems feasible using 'Intelligent Thermal Effect Control'. Clinical evaluations of human eyes are needed to confirm the preliminary simulated results presented here.

  10. Advanced Very High Resolution Radiometer Normalized Difference Vegetation Index Composites

    Science.gov (United States)

    ,

    2005-01-01

    The Advanced Very High Resolution Radiometer (AVHRR) is a broad-band scanner with four to six bands, depending on the model. The AVHRR senses in the visible, near-, middle-, and thermal- infrared portions of the electromagnetic spectrum. This sensor is carried on a series of National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POES), beginning with the Television InfraRed Observation Satellite (TIROS-N) in 1978. Since 1989, the United States Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS) has been mapping the vegetation condition of the United States and Alaska using satellite information from the AVHRR sensor. The vegetation condition composites, more commonly called greenness maps, are produced every week using the latest information on the growth and condition of the vegetation. One of the most important aspects of USGS greenness mapping is the historical archive of information dating back to 1989. This historical stretch of information has allowed the USGS to determine a 'normal' vegetation condition. As a result, it is possible to compare the current week's vegetation condition with normal vegetation conditions. An above normal condition could indicate wetter or warmer than normal conditions, while a below normal condition could indicate colder or dryer than normal conditions. The interpretation of departure from normal will depend on the season and geography of a region.

  11. A new radiological index for assessing asphericity of the femoral head in cam impingement

    DEFF Research Database (Denmark)

    Gosvig, K K; Jacobsen, S; Palm, H;

    2007-01-01

    Femoroacetabular cam impingement is thought to be a cause of premature osteoarthritis of the hip. The presence of cam malformation was determined in 2803 standardised anteroposterior (AP) pelvic radiographs from the Copenhagen Osteoarthritis Study by measuring the alpha (alpha) angle and the tria...

  12. On the evolution of aspherical perturbations in the universe an analytical model

    CERN Document Server

    Popolo, A D

    2002-01-01

    I study the role of shear fields by using an analytical approximate solution for the equations of motion of homogeneous ellipsoids embedded in a homogeneous background. The equations of motion of a homogeneous ellipsoid (Icke 1973; White & Silk 1979 (hereafter WS)) are modified in order to take account of the tidal field as done in Watanabe 1993 and then are integrated analytically, similarly to what done in WS. The comparison of the analytical solution with numerical simulations shows that it is a good approximation to the numerical one. This solution is used to study the evolution of the configuration ofthe ellipsoids, to calculate the evolution of the density contrast and that of the axial peculiar velocity of the ellipsoids for several values of the amplitude of the external tidal field, and compared again with numerical simulations. In order to calculate the evolution of the density contrast at turn-around and collapse velocity at the epoch of collapse, as a function of the ratio of the initial value...

  13. Influence of ocular longitudinal chromatic aberration on the selection of aspheric intraocular lenses.

    Science.gov (United States)

    Hong, Xin; Choi, Myoung

    2010-12-06

    Polychromatic defocus could affect the optimal residual spherical aberration that could yield the best image quality for patients with intraocular lenses (IOLs). Modulation transfer functions (MTFs) were generated using a model that included polychromatic defocus. The maximum MTF volume occurred at + 0.05 μm of overall ocular spherical aberration. For 3 case studies, the optimal overall ocular spherical aberration was ~0.05 μm more positive with the contribution of polychromatic defocus than without it. Overall, the model indicated that image quality was usually best when IOLs allowed overall ocular spherical aberration that was slightly positive, rather than strongly positive, zero, or negative.

  14. Wear-based aspherics generator based on a novel elliptical rotator

    Science.gov (United States)

    Faehnle, Oliver W.; van Brug, Hedser H.; Frankena, Hans J.

    1998-08-01

    Derived from an earlier development (fabrication of ultraprecise surfaces using a tube; patent pending), a new fabrication technique to produce on- and off-axis optical surfaces of revolution is presented. Although based on a shape-copying method, it is possible to generate different types of surfaces with the same machining tool. Load- controlled point-contact machining is applied using a small tool that is guided along a predetermined tool path, not requiring an in-process tool-path control. This fabrication technique constitutes a self-correcting process and is characterized by an advantageous error propagation between tool path and workpiece shape. The characteristics of this fabrication technique are discussed together with its application for the generation of on- and off-axis surfaces with conic sections as generators (`conic surfaces'). We present the design of a first setup for production of conic surfaces that facilitates the generation of all kinds of conic surfaces on the same machine, featuring a pantograph enabling the production of different scales of the surfaces. A discussion of first experimental data is also presented.

  15. Integration of full-spectrum metrology and polishing for rapid production of large aspheres Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Integration of three proven, non-contact, optical metrology techniques with an emerging new polishing approach in a single machine will enable the rapid production...

  16. X-ray structure refinement using aspherical atomic density functions obtained from quantum-mechanical calculations.

    Science.gov (United States)

    Jayatilaka, Dylan; Dittrich, Birger

    2008-05-01

    An approach is outlined for X-ray structure refinement using atomic density fragments obtained by Hirshfeld partitioning of quantum-mechanical density fragments. Results are presented for crystal structure refinements of urea and benzene using these 'Hirshfeld atoms'. Using this procedure, the quantum-mechanical non-spherical electron density is taken into account in the structural model based on the conformation found in the crystal. Contrary to current consensus in structure refinement, the anisotropic displacement parameters of H atoms can be reproduced from neutron diffraction measurements simply from a least-squares fit using the Hirshfeld atoms derived from the BLYP level of theory and including a simple point-charge model to treat the crystal environment.

  17. A new radiological index for assessing asphericity of the femoral head in cam impingement

    DEFF Research Database (Denmark)

    Gosvig, K K; Jacobsen, S; Palm, H

    2007-01-01

    Femoroacetabular cam impingement is thought to be a cause of premature osteoarthritis of the hip. The presence of cam malformation was determined in 2803 standardised anteroposterior (AP) pelvic radiographs from the Copenhagen Osteoarthritis Study by measuring the alpha (alpha) angle and the tria...

  18. NEBU_3D afast pseudo-3D photoionization code for aspherical planetary nebulae and HII regions

    CERN Document Server

    Morisset, C; Peña, M

    2005-01-01

    We describe a pseudo-3D photoionization code, NEBU_3D and its associated visualization tool, VIS_NEB3D, which are able to easily and rapidly treat a wide variety of nebular geometries, by combining models obtained with a 1D photoionization code. We also present a tool, VELNEB_3D, which can be applied to the results of 1D or 3D photoionization codes to generate emission line profiles, position-velocity maps and 3D maps in any emission line by assuming an arbitrary velocity field. As examples of the capabilities of these new tools, we consider three very different theoretical cases. The first one is a blister HII region, for which we have also constructed a spherical model (the spherical impostor) which has exactly the same Hbeta surface brightness distribution as the blister model and the same ionizing star. The second example shows how complex line profiles can be obtained even with a simple expansion law if the nebula is bipolar and the slit slightly off-center. The third example shows different ways to prod...

  19. Null tests for oblate spheroids. [aspheric surfaces in reflecting optical system designs

    Science.gov (United States)

    Rodgers, J. M.; Parks, R. E.

    1984-01-01

    In most real cases requiring simple null optics, the optical path difference cannot be reduced to zero but can be kept at a fractional wavelength level so that interferometric data reduction can be used to account for the residual error. In other cases, computer-generated holograms may be used to obtain apparently straight fringes when the desired surface is obtained. Two examples, one involving an f/2.5 concave oblate spheroid and the other a Paul-Baker secondary, are examined. It is shown that although the null tests are not generally perfect, the residual error is small and the tests are simple.

  20. High PRF high current switch

    Science.gov (United States)

    Moran, Stuart L.; Hutcherson, R. Kenneth

    1990-03-27

    A triggerable, high voltage, high current, spark gap switch for use in pu power systems. The device comprises a pair of electrodes in a high pressure hydrogen environment that is triggered by introducing an arc between one electrode and a trigger pin. Unusually high repetition rates may be obtained by undervolting the switch, i.e., operating the trigger at voltages much below the self-breakdown voltage of the device.