793 research outputs found
The evaluation and prediction of the performance for future GSM-based digital mobile radio systems
Smart and Safe Vehicle Monitoring with Fuzzy Integral and Haar-like Features
An on-board Android-based smart and safe vehicle monitoring system is presented. The on-board monitoring system (OMS) performs important monitoring functions: Record, Report and Alert (RRA). The Record function records front images of a moving vehicle. During the recording, any accidents or other emergency conditions will be automatically reported via the Report function for an emergency rescue operation. For the detection of shocks or accidents, we use acceleration based shock sensors that utilize fuzzy integral algorithm. The OMS also focuses on drowsiness that is largely regarded as the main cause of most accidents. The Haar-like feature is used to detect any sign of drowsiness and the Alert function is performed to alert the driver. All the vehicle-borne information is stored at a remote server via wireless communication links for later use or post-processing. A test bed has been developed and verified thoroughly for its accurate operations. The proposed smart and safe vehicle monitoring system offers advanced safety features and is expected to substantially reduce fatigue related accidents
Optical Camera Communications: Principles, Modulations, Potential and Challenges
Optical wireless communications (OWC) are emerging as cost-effective and practical solutions to the congested radio frequency-based wireless technologies. As part of OWC, optical camera communications (OCC) have become very attractive, considering recent developments in cameras and the use of fitted cameras in smart devices. OCC together with visible light communications (VLC) is considered within the framework of the IEEE 802.15.7m standardization. OCCs based on both organic and inorganic light sources as well as cameras are being considered for low-rate transmissions and localization in indoor as well as outdoor short-range applications and within the framework of the IEEE 802.15.7m standardization together with VLC. This paper introduces the underlying principles of OCC and gives a comprehensive overview of this emerging technology with recent standardization activities in OCC. It also outlines the key technical issues such as mobility, coverage, interference, performance enhancement, etc. Future research directions and open issues are also presented
Optimum Cooperative Spectrum Sensing Technique for Multiuser Ultraviolet Wireless Communications
In this paper, we present a novel optimum cooperative spectrum sensing technique to mitigate multiuser interference for multiuser ultraviolet wireless communications over MƔlaga distributed turbulence channel. We consider the distributed decision fusion for the cooperative sensing. Based on the derived MƔlaga distribution, a mathematically-tractable expression for the average probability of detection is presented. An optimal voting rule is derived to minimize the average error rate. To verify this optimum voting rule, we use the energy detection technique. It is found that the formulated voting rule produces one optimal value only, which indeed confirms its optimum performance
Uncertainties in physiologically based pharmacokinetic models caused by several input parameters
Effects of Infrared Radiation and Heat on Human Skin Aging in vivo
Sunlight damages human skin, resulting in a wrinkled appearance. Since natural sunlight is polychromatic, its ultimate effects on the human skin are the result of not only the action of each wavelength separately, but also interactions among the many wavelengths, including UV, visible light, and infrared (IR). In direct sunlight, the temperature of human skin rises to about 40Ā°C following the conversion of absorbed IR into heat. So far, our knowledge of the effects of IR radiation or heat on skin aging is limited. Recent work demonstrates that IR and heat exposure each induces cutaneous angiogenesis and inflammatory cellular infiltration, disrupts the dermal extracellular matrix by inducing matrix metalloproteinases, and alters dermal structural proteins, thereby adding to premature skin aging. This review provides a summary of current research on the effects of IR radiation and heat on aging in human skin in vivo
Imaging findings in coronavirus infections : SARS-CoV, MERS-CoV, and SARS-CoV-2
During the first two decades of the 21st century, there have been three coronavirus infection outbreaks raising global health concerns by severe acute respiratory syndrome coronavirus (SARS-CoV), the Middle East respiratory syndrome coronavirus (MERS-CoV), and the SARS-CoV-2. Although the reported imaging findings of coronavirus infection are variable and non-specific, the most common initial chest radiograph (CXR) and CT findings are ground-glass opacities and consolidation with peripheral predominance and eventually spread to involve both lungs as the disease progresses. These findings can be explained by the immune pathogenesis of coronavirus infection causing diffuse alveolar damage. Although it is insensitive in mild or early coronavirus infection, the CXR remains as the first-line and the most commonly used imaging modality. That is because it is rapid and easily accessible and helpful for monitoring patient progress during treatment. CT is more sensitive to detect early parenchymal lung abnormalities and disease progression, and can provide an alternative diagnosis. In this pictorial review, various coronavirus infection cases are presented to provide imaging spectrums of coronavirus infection and present differences in imaging among them or from other viral infections, and to discuss the role of imaging in viral infection outbreaks
The impact of sequential versus single anastomoses on flow characteristics and mid-term patency of saphenous vein grafts in coronary bypass grafting
ObjectiveTo assess the influence of bypass grafting technique on the flow characteristics and mid-term patency of saphenous vein coronary bypass grafts.MethodsIn the present study, 309 patients who underwent either sequential (group A, NĀ =Ā 84 grafts) or individual (group B, NĀ =Ā 244 grafts) saphenous vein coronary bypass grafting between February 2002 and September 2007 were investigated. Individual bypassing only was performed in 212 patients, and sequential bypassing only was performed in 78 patients. The remaining 19 patients received both. A total of 436 distal anastomoses were performed with 328 saphenous vein grafts. The intraoperative flow characteristics and the graft patency were assessed with the transit time flow meter and serial multi-detector computed tomography coronary angiograms, respectively.ResultsGroup A showed a higher mean flow compared with group B at 49.4Ā Ā± 27.4 mL/min versus 37.1Ā Ā± 20.1 mL/min, respectively (PĀ =Ā .001). The mean flow increased linearly as the number of anastomoses increased per graft (PĀ <Ā .001). Graft patency at 3 years was 93.3%Ā Ā± 3.4% in group A and 86.5%Ā Ā± 3.1% in group BĀ (PĀ =Ā .048). After adjustment for baseline characteristics, group A showed a tendency for superior mid-term patency than group B (hazard ratio 0.362; 95% confidence interval, 0.129ā1.017; PĀ =Ā .0538).ConclusionsSequential bypass grafts were associated with higher mean flows and superior mid-term patency compared with individual grafts. These findings suggest the more favorable results of sequential bypass grafting to be attributed to the enhanced flow hemodynamics
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