Visibility Improvement Research Articles

Automatic Red-Channel underwater image restoration

Underwater images typically exhibit color distortion and low contrast as a result of the exponential decay that light suffers as it travels. Moreover, colors associated to different wavelengths have different attenuation rates, being the red wavelength the one that attenuates the fastest. To restore underwater images, we propose a Red Channel method, where colors associated to short wavelengths are recovered, as expected for underwater images, leading to a recovery of the lost contrast. The Red Channel method can be interpreted as a variant of the Dark Channel method used for images degraded by the atmosphere when exposed to haze. Experimental results show that our technique handles gracefully artificially illuminated areas, and achieves a natural color correction and superior or equivalent visibility improvement when compared to other state-of-the-art methods.

Seeing more : Technical innovations in regional anesthesia

Visualization and verification are key factors since the implementation of ultrasound-guided regional anesthesia. This article reviews and discusses newer technical innovations in regional anesthesia with regard to optimization of needle guidance, improvements in needle visibility, technical improvements in ultrasound techniques and innovative technologies in regional anesthesia. Clinically available applications are presented as well as experimental tools and techniques with a potential for clinical implementation in the future. Mechanical needle guides are used to improve alignment of needle axis and ultrasound beam axis. Compound imaging technology improves needle visibility in steep needle insertion angles and is already implemented in daily clinical practice. Sonoelastography improves tissue discrimination and detection of small amounts of fluids. Benefits of 3D and 4D ultrasound in regional anesthesia are discussed as well as experimental tools for tissue discrimination, such as optical reflection spectrophotometry.

Sci-Fri AM: Mountain - 02: A comparison of dose reduction methods on image quality for cone beam CT

Modern radiotherapy uses highly conformai dose distributions and therefore relies on daily image guidance for accurate patient positioning. Kilovoltage cone beam CT is one technique that is routinely used for patient set-up and results in a high dose to the patient relative to planar imaging techniques. This study uses an Elekta Synergy linac equipped with XVI cone beam CT to investigate the impact of various imaging parameters on dose and image quality. Dose and image quality are assessed as functions of x-ray tube voltage, tube current and the number of projections in the scan. In each case, the dose measurements confirm that as each parameter increases the dose increases. The assessment of high contrast resolution shows little dependence on changes to the image technique. However, low contrast visibility suggests a trade off between dose and image quality. Particularly for changes in tube potential, the dose increases much faster as a function of voltage than the corresponding increase in low contrast image quality. This suggests using moderate values of the peak tube voltage (100 – 120 kVp) since higher values result in significant dose increases with little gain in image quality. Measurements also indicate that increasing tube current achieves the greatestmore » degree of improvement in the low contrast visibility. The results of this study highlight the need to establish careful imaging protocols to limit dose to the patient and to limit changes to the imaging parameters to those cases where there is a clear clinical requirement for improved image quality.« less

Widespread reductions in haze across the United States from the early 1990s through 2011

Visibility has improved significantly at many remote areas across the United States since the early 1990s. Trends in visibility were calculated using ambient light extinction coefficients (bext) estimated from speciated particulate concentrations measured by the IMPROVE (Interagency Monitoring of Protected Visual Environments) network. The 20% haziest bext levels were computed for each year following Regional Haze Rule guidelines and aggregated over three major regions of the United States. Over the last two decades (1992–2011) the regional mean 20% haziest bext dropped by 52% (−2.6% yr−1, p < 0.01) in the eastern United States, and by 20% (−1.0% yr−1, p = 0.08) for sites along the West Coast. However, in the Intermountain/Southwest region, the trend was insignificant (−0.2% yr−1, p = 0.36). Over the last decade (2002–2011) the haziest bext in the Intermountain/Southwest region decreased by 15% (−1.5% yr−1, p = 0.09), compared to a decrease of 35% (−3.5% yr−1, p = 0.06) in the West Coast region and 50% (−5.0% yr−1, p = 0.02) in the East. A novel aspect to this study is the visualization of trends through the simulation of images of national parks and other remote areas for early and current haziest conditions. These images are an effective means for communicating trends and illustrate the dramatic improvement in visibility, especially in the East, where reductions in sulfate concentrations and sulfur dioxide emissions have had a positive impact on visibility degradation. However, while conditions are clearer for regions in the West, less improvement points to the need for understanding the influences on the trends in haziest conditions in those regions.

Calibration Method for MMW Imaging Using Inexpensive Miniature Neon Indicator Lamp Detectors

We have developed focal plan array (FPA) imagers based on very inexpensive miniature neon indicator lamp detectors called glow discharged detectors (GDDs). The novelty of this paper is a technique of calibration, which permits reliable imaging with such an inexpensive FPA. GDDs are commercial lamps, which lack uniformity as detectors. The technique developed in this paper cancels out differences in response between the FPA lamps caused by both nonuniformity of the MMW collimated beam, and nonuniformity of the GDDs and other components in the electronic circuit. Utilizing this method in the new imaging system unifies detector response. Results, shown with two types of sensor configurations (8 × 8 and 18 × 2 scanner array), indeed show better performances and improvement in visibility of details.

Phase-contrast and magnification radiography at diagnostic X-ray energies using a pseudo-microfocus X-ray source.

To investigate the use of conventional diagnostic X-ray tubes for applications in which specialist microfocus sources are normally required. A conventional diagnostic X-ray tube was used in conjunction with a range of apertures to investigate improvements in spatial resolution using a line-pairs test object. Phase-contrast effects were investigated by varying source-to-object and object-to-receptor distances using a 2-French catheter as a clinically realistic test object. For magnification radiography using a computed radiography receptor and conventional X-ray tube with a 1-mm nominal focus size, the limiting spatial resolution was improved from 3.55 line-pairs per millimetre, for a conventional contact image, to 5.6 line-pairs per millimetre, for a ×2 magnified view with a 250-µm aperture. For inline phase-contrast radiography, phase contrast enhancement of a 2-French catheter was demonstrated, and the expected trends with variations in source-to-object and object-to-receptor distances were found. Images of a neonatal phantom demonstrated a subtle improvement in visibility of a superimposed 1-French catheter simulating a percutaneously inserted central catheter for no increase in patient radiation dose. Spatial resolution improvement and visible phase contrast can be produced in clinically relevant objects using a pseudo-microfocus geometry at X-ray energies in the normal diagnostic range, using conventional diagnostic X-ray tubes and image receptors. The disadvantages of the proposal are the large distances required to produce phase contrast and limitations imposed by the resulting tube loading. It is possible to use conventional diagnostic X-ray equipment in applications that normally require microfocus X-ray sources. This presents some possibilities for clinical applications.

A multi-year evolution of aerosol chemistry impacting visibility and haze formation over an Eastern Asia megacity, Shanghai

A multi-year (2004–2008) study of horizontal visibility and factors controlling its variations was conducted in Shanghai. The seasonal average visibility in spring, summer, autumn, and winter was 7.7 km, 8.4 km, 8.1 km, and 6.5 km, respectively, significantly exceeding the haze criteria of 10 km throughout all four seasons. Although SO2 and NO2 concentrations gradually shifted to lower levels on an annual basis, no distinct improvement of the annual mean visibility was noticed. Via a grouping method, it was found that the water soluble ions and black carbon were the major contributors to haze formation while the role of mineral aerosol was negligible. Of the ions, SO42−, NO3−, NH4+, K+, and C2O42− were most associated with the formation of heavy haze. SO42− and NO3− were both found to have significant decreasing trends with annual decreasing rates of 0.96 and 0.56 μg/m3/yr, respectively. Conversely, NH4+ showed a significant increasing trend with the annual increasing rate of 0.52 μg/m3/yr. Based on a quantitative correlation analysis, the roles of NH4+ and Ca2+ on the acids neutralization were almost equivalent in the earlier years of 2004–2005. While the role of Ca2+ had tremendously dropped to less than 23% in the later years of 2006–2008. Intense control measures on the emissions of construction works and roadside dust were the main driving force for the evident decreasing trend of annual Ca2+ concentrations. This study found that the gradual replacement of CaSO4 and Ca(NO3)2 by (NH4)2SO4 and NH4NO3 in aerosol was the major cause of no improvement of the visibility impairment in Shanghai during recent years.

A Multi-Year Aerosol Characterization for the Greater Tehran Area Using Satellite, Surface, and Modeling Data.

This study reports a multi-year (2000–2009) aerosol characterization for metropolitan Tehran and surrounding areas using multiple datasets (Moderate Resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging Spectroradiometer (MISR), Total Ozone Mapping Spectrometer (TOMS), Goddard Ozone Chemistry Aerosol Radiation and Transport (GOCART), and surface and upper air data from local stations). Monthly trends in aerosol characteristics are examined in the context of the local meteorology, regional and local emission sources, and air mass back-trajectory data. Dust strongly affects the region during the late spring and summer months (May–August) when aerosol optical depth (AOD) is at its peak and precipitation accumulation is at a minimum. In addition, the peak AOD that occurs in July is further enhanced by a substantial number of seasonal wildfires in upwind regions. Conversely, AOD is at a minimum during winter; however, reduced mixing heights and a stagnant lower atmosphere trap local aerosol emissions near the surface and lead to significant reductions in visibility within Tehran. The unique meteorology and topographic setting makes wintertime visibility and surface aerosol concentrations particularly sensitive to local anthropogenic sources and is evident in the noteworthy improvement in visibility observed on weekends. Scavenging of aerosol due to precipitation is evident during the winter when aconsistent increase in surface visibility and concurrent decrease in AOD is observed in the days after rain compared with the days immediately before rain.

Black carbon and organic carbon emissions from wildfires in Mexico

In Mexico, approximately 7650 wildfires occur annually, affecting 263 115 hectares of land. In addition to their impact on land degradation, wildfires cause deforestation, damage to ecosystems and promote land use change; apart from being the source of emissions of toxic substances to the environment (i.e., hydrogen cyanide, black carbon and organic carbon). Black carbon is a short-lived greenhouse pollutant that also promotes snow and ice melting and decreased rainfall; it has an estimated global warming potential close to 5000.1 We present an estimate of the black carbon and organic carbon emissions from wildfires in Mexico from 2000 to 2012 using selected emission factors from the literature and activity data from local agencies. The results show average emissions of 5955 Mg/yr for black carbon and 62 085 Mg/yr for organic carbon. Black carbon emissions are estimated to be 14 888 Gg CO2 equivalent (CO2 eq) per year on average. With proper management of wildfires, such emissions can be mitigated. Moreover, improved air quality, conservation of ecosystems, improvement of visibility and maintenance of land use are a subset of the related co-benefits. Mitigating forest organic carbon emissions, which are ten times higher than black carbon emissions, would also prevent the morbidity and mortality impacts of toxic organic compounds in the environment.1The GWP is calculated as the ratio of the Absolute Global Warming Potential (AGWP) of a given gas to the AGWP of CO2. The AGWP has units of Wm–2 g–1 yr.

Comparative study on long-term visibility trend and its affecting factors on both sides of the Taiwan Strait

The rapid industrial development and urbanization has lead to increasing particulate matter pollution in the Cross Taiwan Strait Region, which has significant impacts on atmospheric visibility degradation. Long-term visibility trends in five typical cities over the cross-strait region (i.e., Xiamen and Fuzhou in the Western Taiwan Strait (WTS) region and Taipei, Taichung and Tainan in Taiwan) and its correlation with air quality and meteorological conditions were investigated using visibility and meteorological data during 1973–2011 and air pollution data during 2009–2011. For the entire period, the overall average visibilities in the WTS region were better than those in Taiwan, with an average of 16.8, 16.6, 8.5, 10.3 and 9.0km in Fuzhou, Xiamen, Taipei, Taichung and Tainan, respectively. Decline trends with decreasing rates of −0.5–0.1km/yr existed in all cities except Taipei, which had an improvement in visibility after 1992. All seasons had decreasing trends during the 39-year period except in Taipei. The WTS region had the worse change trend compared with Taiwan. No statistically significant weekend effect in visibility is found over the region. Visibilities were better in summer and autumn, while worse in winter and spring. Correlation analysis revealed that significant negative correlations existed between visibility and NO2 and airborne particles (i.e., PM10 and PM2.5); PM2.5 played an important role in visibility degradation. High temperature and low pressure is beneficial for better visibility. Principal component analysis further confirmed the impacts of high concentrations of air pollutants, stable synoptic systems and humid air with high relative humidity on visibility impairment. In addition, case studies highlighted characteristics and potential causes of typical regional low visibility episodes over the region.

The benefits of supply chain visibility: A value assessment model

In recent years, much attention has been devoted to the topic of supply chain visibility in the scientific literature. However, a thorough assessment of the benefits enabled by supply chain visibility has not yet been undertaken. This paper aims to provide a structured method and a set of assessment tools for quantifying the benefits that can be achieved through better visibility on the inbound supply chain. The method consists of a nine step process for assessing the value of an improvement in supply chain visibility; the tools are ten causal maps, which depict the KPIs affected by an improvement in the quality and/or quantity of focal company׳s visibility on specific information flows (e.g. order status, inventory level, delivery plan, etc.). The method is based on the literature, while the tools were developed through a focus group of nine practitioners. The resulting model (i.e. method and tools) was applied to the supply chain of a prominent company in the aerospace industry in order to explore its applicability in a practical context. The model proved to be efficient, since it could be easily customised in accordance with the level of effort managers wanted to put into the evaluation, and effective, thus providing reliable estimates of likely KPI improvements.

Effectiveness of two interventions in preventing traffic accidents: a systematic review.

The prevention of road traffic accidents should be considered a serious public health concern, since they are the eighth leading cause of death globally and the main cause of death for young people aged 15-29. Evidences from many countries show that successes in preventing road traffic injuries can be achieved through concerted efforts at national level. The aim of our study was to assess the effectiveness of two interventions to prevent road traffic accidents: the introduction of graduated driver licensing (GDL) and the interventions to improve pedestrian and cyclist visibility. Our search started with a scoping review on the interventions to prevent road traffic accidents to allow the development of a logical framework of traffic accidents. Specific and answerable questions formulated according to PICO scheme and combinations of keywords were used to perform a systematic search in the following databases: Pubmed, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (DARE), Health Evidence, Transport Research International Documentation (TRID) and Google. References of selected papers were searched. Only systematic reviews and meta-analyses were eligible. No temporal limits or linguistic filters were applied. 160 systematic reviews and meta-analyses were found for the question of the introduction of GDL program and 188 on the improvement of visibility in cyclists and pedestrians. After selection, four papers were included in qualitative synthesis for each question. All included studies underwent quality evaluation. GDL programs seem to be effective in reducing crash rates among young drivers, in particular in 16 year-old. Programs with more restrictions seem also to reduce fatal events. To improve visibility of pedestrians and cyclists, street lighting has been suggested as an intervention able to improve driver's visual capabilities and ability to detect roadway hazards and to prevent car crashes. Visibility aids (fluorescent materials, lamps, flashing lights and retroreflective materials) have the potential to increase visibility and enable drivers to detect pedestrians and cyclists earlier. The two interventions seem to be effective, but further examinations are needed to measure long-term effects. It is necessary to provide feasible studies in local context to estimate the impact of introduction of GDL programs or of some of their components and to improve interventions to increase visibility of pedestrians and cyclists.

Integrating Visibility, Parking Restriction, and Driver's Field View for Enhancing Pedestrian Crossing Safety

Pedestrians at a marked but unsignalized pedestrian crossing (Ped-Xing) must be made visible to drivers in the approaching traffic at a sufficient distance away from the crossing, and this distance is needed for stopping a vehicle before the leading Ped-Xing edge to avoid a potential traffic collision. In this paper, an exact analytic framework is established to integrate driver's field view, driver's perception-reaction, lighting condition, and parking restriction at a Ped-Xing for enhancing traffic operational safety. The size of the no parking zone by the Ped-Xing is determined exactly using equations derived from this framework. Additionally, this study sheds the light on mid-block Ped-Xing installation, which should be discouraged if parking is permitted alongside a street. Furthermore, additional visibility improvement measures at the unsignalized Ped-Xings may be needed for enhancing safe traffic operations at the crossings.

Role of sectoral and multi-pollutant emission control strategies in improving atmospheric visibility in the Yangtze River Delta, China

The Community Multi-scale Air Quality modeling system is used to investigate the response of atmospheric visibility to the emission reduction from different sectors (i.e. industries, traffic and power plants) in the Yangtze River Delta, China. Visibility improvement from exclusive reduction of NOx or VOC emission was most inefficient. Sulfate and organic aerosol would rebound if NOx emission was exclusively reduced from any emission sector. The most efficient way to improve the atmospheric visibility was proven to be the multi-pollutant control strategies. Simultaneous emission reductions (20–50%) on NOx, VOC and PM from the industrial and mobile sectors could result in 0.3–1.0 km visibility improvement. And the emission controls on both NOx (85%) and SO2 (90%) from power plants gained the largest visibility improvement of up to 4.0 km among all the scenarios. The seasonal visibility improvement subject to emission controls was higher in summer while lower in the other seasons.

Application of CAD and reverse engineering methodology for development of complex assemblies

Purpose – In the present paper, a CAD and reverse engineering (RE) methodology has been adopted for the development of a complex assembly of a TFC 280 crane cabin. A different approach has been adopted to eliminate fouling as well as interference with other components of the crane such as boom, gantry, front drum, rear drum, etc. with its cabin. The paper aims to discuss these issues. Design/methodology/approach – A dummy 3-D CAD model of the assemblies has been made using assembly constraints of Master Assembly and then checked for fouling and interference using IDEAS NX 12 to validate cabin design. In fabrication industries, one of the critical challenges is to maintain close geometric tolerances in finished products, which have been taken care of by the use of accurate value of K-factor. Findings – Ergonomics of the re-engineered crane cabin has also been improved by providing rear vision and improvement in operator's forward visibility from 165° to 180°. Originality/value – The work has been carried out using RE methodology un-used in this part of the world (Jamshedpur, India).

CLINICAL EVALUATION AND FEASIBILITY OF CHANGING INTRAOPERATIVE VISIBILITY WITH A NOVEL VIEWING FILTER SYSTEM FOR HUMAN EYE

The study was conducted to develop a new viewing system as a clinical prototype that enables visibility during surgery. The system was composed of several filters attached to the microscope. This nonrandomized, retrospective, observational case series study involved 33 eyes from 32 patients who presented with various diseases and underwent surgery. The authors evaluated the changes in visualization focusing on controlling intraoperative visibility under air infusion and enhancing Brilliant Blue G staining focusing a sharp-cut filter Y (SCY). Visibility was compared under various surgical conditions, including cataract surgery, both with and without this system. Quantitative analysis of changes in intraoperative reflection including halation under air infusion and Brilliant Blue G intensity was carried out using the International Commission on Illumination 1976 (L*, a*, b*) color space method. A SCY reduced the reflection and halation by a maximum of 69.6%, when compared with use of no filter under air infusion (P < 0.01). The color difference between Brilliant Blue G-stained and nonstained areas was improved by 127.8% relative to values with no filter and using SCY (P < 0.01) in macular hole cases. Furthermore, in cataract surgery with corneal opacity, improvement of visibility was observed by SCY insertion. The system improved intraoperative visibility under air infusion and the Brilliant Blue G staining intensity by use of SCY during vitrectomy.

Improved Brilliant Blue G Staining of the Internal Limiting Membrane with Sharp Cut Filters of a Novel Viewing Filter System

Purpose: We developed a new artificial image enhancement system aimed at intraoperative visibility improvement as a clinical prototype. We examined each optical characteristic and change in intraoperative visibility using brilliant blue G (BBG) staining with various sharp cut filters (SCFs). Method: This was a retrospective and observational study. The system was composed of several filters attached to the operating microscope. Six eyes from 6 patients who presented with macular hole and underwent surgery using this system were studied. As a clinical examination, the intraoperative visibility of BBG staining intensities was compared for 4 kinds of SCFs during vitrectomy. Quantitative evaluation was calculated using the International Commission on Illumination 1976 (L*, a*, b*) color space (CIELAB) method. Furthermore, we evaluated each optical characteristic of 4 types of SCFs using extracted porcine eyes and a spectroradiometer as a clinical simulation. Results: Suitable filter selection was possible for this system. The observed color tone and spectral irradiance changes with SCF insertion changed dynamically. In macular hole cases, the color intensities between BBG-stained and nonstained areas were improved using SCF-455 and SCF-520, which was statistically significant (p < 0.05) by CIELAB. Conclusion: The system improved BBG staining intensity with the use of selective SCFs.

25aBB-6 量子非破壊測定による量子測定の可視度の改善(量子エレクトロニクス(量子コンピューター・デコヒーレンス),領域1(原子・分子,量子エレクトロニクス,放射線物理))

25aBB-6 量子非破壊測定による量子測定の可視度の改善(量子エレクトロニクス(量子コンピューター・デコヒーレンス),領域1(原子・分子,量子エレクトロニクス,放射線物理))

Study on Contraction of Dust Control System in Continuous Coal Mining

Most of the dust control models indicate the line-curtain air reaching the face is limited and does not extend. Lower air quantity at the face helps in containing and concentrating the dust close to the face where no occupations are present. Hence, effective use of hydraulic sprays and directing the face dust-laden air into the scrubber may improve dust control. In this paper, we put forward a field testing of the modified scrubber-modified continuous miner demonstrated significant improvements in visibility and dust and quartz reduction, as compared to what was achieved with the current scrubber-current continuous miner dust control system. This is unfavorable from methane dilution point of view but can be used to advantage for improved dust control.

Short-Lag Spatial Coherence Imaging of Cardiac Ultrasound Data: Initial Clinical Results

Short-lag spatial coherence (SLSC) imaging is a novel beamforming technique that reduces acoustic clutter in ultrasound images. A clinical study was conducted to investigate clutter reduction and endocardial border detection in cardiac SLSC images. Individual channel echo data were acquired from the left ventricle of 14 volunteers, after informed consent and institutional review board approval. Paired B-mode and SLSC images were created from these data. Contrast, contrast-to-noise, and signal-to-noise ratios were measured in paired images, and these metrics were improved with SLSC imaging in most cases. Three cardiology fellows rated the visibility of endocardial segments in randomly ordered B-mode and SLSC cine loops. SLSC imaging offered 22%–33% improvement (p < 0.05) in endocardial border visibility when B-mode image quality was poor (i.e., 80% or more of the endocardial segments could not be visualized by the three reviewers). The percentage of volunteers with poor-quality images was decreased from 21% to 7% with the SLSC beamformer. Results suggest that SLSC imaging has the potential to improve clinical cardiac assessments that are challenged by clutter.