Maximum Visibility Research Articles

Locally Geostationary Orbits: Optimal Geometry of Elliptic Orbit for Earth Coverage

The problem of satellite constellation design for Earth coverage using elliptic orbit is considered. Whereas various researchers in this field have mainly considered optimization of the orbital structures of constellations, this paper deals with a previously insufficiently studied problem of optimizing the orbital geometry by coverage characteristics, that is, selecting the form of an elliptic orbit (semimajor axis and eccentricity) to provide the best performance in terms of coverage. From this point of view the class of the so-called locally geostationary orbits is suggested and substantiated. It is shown that optimization in the class of locally geostationary orbits, while the problem of Earth coverage on elliptic orbits is considered, leads to maximum duration of the satellite visibility zones. It is shown that this class of orbits includes the geostationary orbit, the only circular orbit in the class, and known Molniya-type elliptic orbit, as well as an infinite domain of elliptic orbits corresponding to the maximum visibility zone duration among all possible elliptic orbits. The general mathematical relations and optimal solution peculiarities for locally geostationary orbits design are presented.

Underwater Optical Imaging for Automotive Wading.

An underwater imaging system was investigated for automotive use in highly scattered underwater environments. The purpose of the system is the driver’s information about hidden obstacles, such as stones, driftwood, open sewer hatches. A comparison of various underwater vision methods was presented by the way they are implemented, the range reached, and the cost of implementation. It has been experimentally shown that a conventional active system can provide a maximum visibility range of up to three light attenuation lengths. In most practical cases of turbid waters during floods, this corresponds to distances of about 1 meter. From the presented analysis it follows that advanced extended range imaging methods allow increasing of the visibility range up to 2 meters.

System Design and Evaluation of a Compact and High Energy X-ray Talbot-Lau Grating Interferometer for Industrial Applications

X-ray grating interferometry has been an active area of research in recent years. In particular, various studies have been carried out for the practical use of the x-ray grating interferometer in medical and industrial fields. For the commercialization of the system, it needs to be optimized for its application. In this study, we have developed a prototype of the compact high energy x-ray grating interferometer of which the high effective energy and compactness is of our primary feature of design. We have designed the Talbot-Lau x-ray interferometer in a symmetrical geometry with an effective energy of 54.3 keV. The system has a source-to-analyzer grating distance of 788.4 mm, which is compact enough for a commercial product. In a normal operation, it took less than ten seconds to acquire a set of phase stepping images. The acquired images had a maximum visibility of about 15%, which is relatively high compared with the visibilities of the other high-energy grating interferometric systems reported so far.

Maximizing Young fringe visibility with a universal SU2 polarization gadget: erratum.

In this erratum, the experimental value of the maximum attainable visibility reported in Opt. Lett.43, 2844 (2018)OPLEDP0146-959210.1364/OL.43.002844 has been corrected.

Maximizing Young fringe visibility with a universal SU2 polarization gadget.

When a Young interferometer is fed by a general electromagnetic field, the fringe visibility may change upon insertion of an anisotropic optical element over one of the interferometer pinholes. The maximum visibility that the fringes may exhibit in this way is theoretically known, but no direct experimental check seems to be available. Here we discuss the scheme of an experimental test. In particular, maximum fringe visibility is obtained with a three-component universal SU2 polarization gadget for arbitrary coherence features of the illuminating field. Confirming results obtained with a suitable experimental setup are presented.

Where are the sleeping beauties and princes in educational technology journals?

PurposeThe purpose of this paper is to introduce an affective computing-based method of identifying sleeping beauties and their princes in five educational technology journals.Design/methodology/approachThis study develops an information technology-based methodology to analyze sleeping beauties in the field of educational technology. The authors seek to determine the characteristics of studies which trigger the awakening of sleeping beauties (called “princes”). The keywords and Hirsch index (H-index) are used as two essential analysis indicators.FindingsBetween 2000 and 2015, these five journals included 7,864 articles with a total of 77,700 citations and 24,312 keywords. This study identified articles as being in deep sleep (75.7 percent), less deep sleep (14.7 percent), and awakening (5.5 percent) states. According to the analytical results, 431 of 7,864 articles are qualified as “sleeping beauties.” Of the 431 sleeping beauties identified, 232 articles were awakened by trend princes, while 286 were awakened by H-index princes. A total of 128 sleeping beauties were awakened by both prince types. Besides, impact factors (IFs) of journals do not have a significant effect on the number of sleeping articles.Research limitations/implicationsThere are two main research limitations in this study. The first one is the amount of target journals. Only five well-known educational technology journals are analyzed in this research. There may be more valuable sleeping publications in other journals not been found. The second limitation is that the authors merely pick up the lead author of citing papers as the indicator to determine the H-index prince. The contributions of the rest of authors are not taken are not taken into consideration. These limitations should be further studied.Originality/valueTo the knowledge, this study is the first one reporting the identification of sleeping beauty and princes in educational technology field. Furthermore, the authors devise an informational method to determine sleeping publications, sleeping beauty, and princes. A systematic analysis of five well-known journals in the field of educational technology field confirms the existence of “sleeping beauties.” It is reported that improvements to a journal’s IF are positively correlated to increased numbers of sleeping beauties being awakened. To reduce the number of such articles, or to reduce the overall sleeping duration, journal editors should not only seek to raise the journal’s IF, but also strategically select keywords for maximum visibility, and promote articles to high H-index authors.

‘Stimulating our Literature and Deepening our Culture’.

One of the most prominent book clubs in the US was the Book-of-the-Month Club, established in 1926. The Book-of-the-Month Club marketed books as commodities for consumption, promoting leisurely reading among the growing middle class. But the Book-of-the-Month Club also claimed to be ‘stimulating our literature and deepening our culture’, and in fact, dozens of selected authors went on to receive the Pulitzer Prize or the Nobel Prize for Literature. The body of research on the Book-of-the-Month Club includes Janice A. Radway’s well-known multi-method study A Feeling for Books (1997). But translations among Book-of-the-Month Club selections have not yet been considered.Focusing in particular on books translated into English from German, this paper will present new data on originally foreign-language books that were selected by the Book-of-the-Month Club judges, thereby guaranteeing European authors maximum visibility and exorbitant sales in the US market, which was (and is) usually considered difficult to tap into for non-Anglophone writers.

WITHDRAWN: Visibility trends in six cities of central China for the period 1974–2016

The fine particulate matter pollution problems have been paid attention in central China since recent years. The pollution levels could be indicated by atmospheric visibility, which is inversely related to the optical extinction coefficient caused mostly by particle matters in China. In this study, the trends of visibilities in six cities in central China (Wuhan, Changsha, Hefei, Nanchang, Zhengzhou, and Taiyuan) were evaluated by using data from the National Climatic Data Center during 1974 to 2016. Four indexes were used, the days per year of daily visibility 19 km, the annual mean visibility, and the dry extinction coefficient. The annual and seasonal change trends of visibility for each city were analyzed by using a linear regression model. The analysis showed that annual visibility in all six cities has decreased, especially in Hefei, having a sharp visibility reduction of − 0.2380 km/year. Typically, visibility in all six cities is better in spring and summer than in autumn and winter. The minimum annual mean visibility was 6.07 km in Wuhan in 2014, while the maximum visibility was not more than 16.54 km in Nanchang in 1976 over the study period. Both values are much lower than the national mean visibility of 26 km. These data clearly show the worsening air quality in cities in central China, which is of strategic significance for the development of the central region.

An Integer Programming Approach for Patrol Police Allocation in an Urban City in the Philippines

Objectives: Philippine National Police (PNP) directed all PNP units to deploy policemen to perform beat patrolling duties for maximum police visibility as well as to intensify law enforcement operations, anti-criminality campaign and public safety services. Beats or beat areas are the areas where policemen are assigned to patrol. In conducting patrols, the officers intermingle and work with the general populace. Due to the limited number of available policemen to be assigned in the beats, this paper aims to solve a Patrol Police Allocation Problem (PPAP) which consists of allocating policemen to beat areas to ensure optimum police visibility in the Central Business District (CBD) of Cagayan de Oro City, Philippines. Methods: In this study, an integer programming model for the PPAP is developed and solved, while considering various characteristics of beat areas and the number of available of patrol police to be assigned. Findings: Results of the study show that the proposed model provides better police visibility than the current police allocation around the CBD of the city. Application: Results of this study will provide insights on how patrol police can be optimally allocated in various beat patrol areas. Keywords: Integer Programming, Patrol Police, Police Assignment Problem

What is the maximum attainable visibility by a partially coherent electromagnetic field in Young's double-slit interference?

What is the maximum visibility attainable in double-slit interference by an electromagnetic field if arbitrary - but reversible - polarization and spatial transformations are applied? Previous attempts at answering this question for electromagnetic fields have emphasized maximizing the visibility under local polarization transformations. I provide a definitive answer in the general setting of partially coherent electromagnetic fields. An analytical formula is derived proving that the maximum visibility is determined by only the two smallest eigenvalues of the 4×4 two-point coherency matrix associated with the electromagnetic field. This answer reveals, for example, that any two points in a spatially incoherent scalar field can always achieve full interference visibility by applying an appropriate reversible transformation spanning both the polarization and spatial degrees of freedom - without loss of energy. Surprisingly, almost all current measures predict zero-visibility for such fields. This counter-intuitive result exploits the higher dimensionality of the Hilbert space associated with vector - rather than scalar - fields to enable coherency conversion between the field's degrees of freedom.

Enhancing interferometer phase estimation, sensing sensitivity, and resolution using robust entangled states

With the goal of designing interferometers and interferometer sensors, e.g., LADARs with enhanced sensitivity, resolution, and phase estimation, states using quantum entanglement are discussed. These states include N00N states, plain M and M states (PMMSs), and linear combinations of M and M states (LCMMS). Closed form expressions for the optimal detection operators; visibility, a measure of the state’s robustness to loss and noise; a resolution measure; and phase estimate error, are provided in closed form. The optimal resolution for the maximum visibility and minimum phase error are found. For the visibility, comparisons between PMMSs, LCMMS, and N00N states are provided. For the minimum phase error, comparisons between LCMMS, PMMSs, N00N states, separate photon states (SPSs), the shot noise limit (SNL), and the Heisenberg limit (HL) are provided. A representative collection of computational results illustrating the superiority of LCMMS when compared to PMMSs and N00N states is given. It is found that for a resolution 12 times the classical result LCMMS has visibility 11 times that of N00N states and 4 times that of PMMSs. For the same case, the minimum phase error for LCMMS is 10.7 times smaller than that of PMMS and 29.7 times smaller than that of N00N states.

Determining the Effectiveness of Mirrors and Camera Systems in Monitoring the Rearward Visibility of Self-Propelled Agricultural Machinery.

This study concerned the ability of operators of tractors and other self-propelled agricultural machinery to visually recognize objects and/or hazards within close proximity to the rear of those machines and/or any implements in tow, especially when backing up. It was hypothesized that the data collected would identify the factors affecting rearward visibility and help determine the effectiveness of two backup-assisting devices (i.e., mirrors and camera systems) in enhancing the operator's ability to observe objects or hazards. The study's experimental design involved the following: (1) selecting nine self-propelled machines for testing (five tractors of varying sizes, a combine, a sprayer, a skid steer loader, and a UTV); (2) laying out a five cell by five cell test grid behind each machine, with an indicator pole centered in each cell; (3) positioning the mirrors (exterior/interior) and camera system (camera and display monitor) for maximum visibility; and (4) collecting images from a 50th percentile male operator's eye midpoint position. The findings were recorded graphically onto a master grid for the backup-assisting devices (both individually and in combination) on each machine. Analysis of the results confirmed that various issues related to the machines impact the effectiveness of mirrors and camera systems in enhancing rearward visibility. Among them are the operator station's design and configuration, seat adjustability, optional accessories, exterior lighting, type of implement in tow, hitching method, and highway transport mode. These findings led to recommendations relative to each of the mirrors and camera systems, as well as observations of operator interactions with accessories and perceived effects on the operator's ability to view obstructed areas in close proximity to the machinery.

A Comparative Analysis of Patient Visibility, Spatial Configuration and Nurse Walking Distance in Korean Intensive Care Units(ICUs) - Focused on single corridor, Pod and Composite type units

Purpose: The purpose of this paper is to analyze a sample of single corridor, pod type and composite type of ICUs in terms of patient visibility, spatial configurations and nurse walking distance focused on Korean cases. Methods: The measures of static visibility were used to quantify the patient visibility (upper third part of the patient bed) from the nurse station. The measure of space programme and area distribution (patient zone percentage, staff zone percentage, circulation zone percentage, corridor length per bed, distance from nurse station (NS) to patient bed and departmental gross square meter (DGSM) per patient bed) were calculated by using AutoCAD and MS Excel programs. In the second step of analysis the values of space distribution were compared among the three type of ICUs as well as the nurse walking distance, DGSM per bed and gross factor. in the third step of analysis regression analysis was conducted for the possible correlation between visibility and space programme and area distribution factors as well as nurse walking distance factors. Results: (1) It was found that on average composite type unit offer highest value of patient visibility followed by pod type, while single corridor type unit offers the minimum value of patient visibility among the three plan typologies. (2) Average patient visibility and DGSM per bed shows a strong positive correlation (<TEX>$r^2=0.75$</TEX>) and p=0.026. (3) Average patient visibility and average distance from NS has a strong negative correlation (<TEX>$r^2=0.78$</TEX>), and P=0.02. (4) On average composite type unit offer the minimum walking distance from NS (7.22 meter) followed by pod type unit (8.35 meter) and single corridor (9.76 meter). (5) Maximum distance from NS was noted in single corridor (18.19 meter) followed by pod type unit (15.14 meter) and Composite type unit (11.1 meter). Implications: This study may contribute to the visibility analysis of existing and future ICU design in Korea to achieve maximum patient visibility and reduced nurse walking distance.

Simultaneous measurement of refractive index, strain, and temperature based on a four-core fiber combined with a fiber Bragg grating

A fiber optic sensor capable of measuring refractive index (RI), strain, and temperature simultaneously is proposed and demonstrated. The sensor is formed by the integration of a four-core fiber (FCF) with a fiber Bragg grating (FBG). When the FCF is kept straight, a pronounced interference pattern appears in the transmission spectrum. Compared with previously reported optical fiber modal interferometers, higher fringe visibility can be obtained in our scheme. The maximum fringe visibility of the interference resonance dips exceeds 21dB. By monitoring the wavelength shifts of three dips, simultaneous measurement of RI, strain, and temperature can be achieved. For 10pm wavelength resolution, the resolution of the sensor is 0.0004RIU, 11.06με, and 0.17°C in RI, strain, and temperature, respectively. The proposed sensor has the advantages of easy to construct, higher fringe visibility, and the capability to measure RI, strain, and temperature simultaneously, which are desirable features in RI measurement.

Fringe visibility degeneration utilizing a rotating optical flat for holographic multiplexing purposes.

A device concept utilizing a rotating optical flat to degenerate the fringe visibility for simultaneously holographic multiplexing purposes is presented. The device basically consists of a rotating slanted optical flat. The rotation induces a periodically varying phase shift to a transmitting wave, which causes a specific degeneration of the maximum achievable time-average visibility. This property can be used to expose independent gratings simultaneously into one photopolymer film with a single coherent light source. Theoretical investigations of the resulting time-average visibility are carried out and presented in detail. Experimental results are compared to the theoretical findings and discussed. The presented device is capable of decreasing the visibility to the desired degree. Thus, it is well suited for holographic multiplexing purposes. A conceptual setup utilizing the device for holographic angular multiplexing is suggested.

A Study on the Development of Predictive Model for Patient Visibility in Korean Intensive Care Units (ICUs) - Focused on "Corridor or Continental" type units

Purpose: The purpose of this paper is to develop a predictive model for patient visibility in Korean ICUs (corridor or continental type). Methods: The measures of static visibility were used to quantify the patient visibility (upper third part of the patient bed) from the nurse station. The measure of space programme and area distribution (patient zone percentage, staff zone percentage and departmental gross square meter per patient bed) were calculated by using AutoCAD and MS Excel programs. Regression analysis was conducted for visibility as dependant variable with independent variables of patient area percentage, staff area percentage as well as departmental gross square meter per bed by using IBM SPSS. Results: (1) Average patient visibility and percentage of patient area in ICU shows a strong negative correlation (<TEX>$r^2$</TEX>=0.66), p=0.01. (2) Patient visibility in Korean ICU (corridor or continental type) can be calculated as below with the given conditions: Y= <TEX>$-1.449(X)+124.3{\pm}6$</TEX>, Y is the total visibility of the ICU (corridor or continental type) and X is the percentage of patient area in the unit. Conditions:1. Given that the unit has a mixed programme of open bed and closed patient rooms and 2. The unit have a minimum of 20% patient rooms. Implications: This study may contribute to the visibility analysis of existing and future ICU design (corridor or continental type) in Korea to achieve maximum patient visibility and reduced patient mortality.

Migration of legacy data to new media formats for long-time storage and maximum visibility: Modern pollen data from the Canadian Arctic (1972/1973)

This Data Management Plan (DMP) was created using the DMPTool. It describes modern pollen data collected along a 2500 mile (~4000 km) transect in the Canadian Arctic in 1972/73 as part of an NSF funded research project (GB-33497). The project was undertaken at the Institute of Arctic and Alpine Research at the University of Colorado Boulder. This legacy dataset originally stored as a paper copy and on 35-mm film will be migrated to digital formats that allow upload of the dataset to an international open-access library for permanent storage and visibility. This DMP was submitted to the 2015 Best Digital Data Management Plan and Practices - Competition (https://data.colorado.edu/cudmpguidance). The study provides a baseline pollen dataset for the interpretation of Holocene pollen diagrams from this region and for comparison with modern surface pollen samples, allowing the assessment of the effects of modern climate change on Arctic and subarctic ecosystems.

All-fiber multipath Mach⬜Zehnder interferometer based on a four-core fiber for sensing applications

A novel, simple and compact optical fiber sensor based on multipath Mach-Zehnder interferometer (m-MZI) is proposed and experimentally demonstrated. The device consists of a segment of four-core fiber (FCF) spliced between two single-mode fibers (SMFs). When the m-MZI is kept straight, an obvious interference pattern appears in the transmission spectrum. Compared with previously reported optical fiber modal interferometers, higher phase sensitivity can be obtained in our scheme due to the multipath interference configuration embedded in one fiber. The maximum fringe visibility of the interference resonance dips exceeds 23dB. The interference fringe of the FCF would shift with the variation of strain, temperature, refractive index (RI) and curvature. So it is possible to measure these parameters by simply monitoring the wavelength shifts. Experimental results show that the sensitivities of the sensor in strain, temperature, RI and curvature are 1.78pm/μe, 209pm/°C, 91.39nm/RIU and 20.18nm/m↙1, respectively. To the best of our knowledge, the multi-purpose sensing applications of the sensor have been experimentally investigated for the first time. Moreover, the proposed sensor has the advantages of high fringe visibility and simple fabrication process.

Erratum to: The shocking consequences of hybrid epigenomes.

The online version of the original article can be found under doi: 10.1186/s13059-016-0967-3 .

Erratum to: Alphacoronavirus in urban Molossidae and Phyllostomidae bats, Brazil.

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