scholarly journals Effects of Site-Dependent Errors on the Accuracy of C/A Code DGPS Positioning

2018 ◽  
Vol 4 (10) ◽  
pp. 2296
Author(s):  
Thilantha Lakmal Dammalage
Keyword(s):  
Processing Technique ◽  
Gps Receiver ◽  
Differential Gps ◽  
Multipath Mitigation ◽  
Different Types ◽  
Before And After ◽  
Gps Processing ◽  
Processing Techniques ◽  
Dependent Error ◽  
User Location

Several differential GPS processing techniques can be used; for instance, single differencing and double differencing, which are popular in practice. Irrespective of the DGPS processing technique used, the ultimate accuracy of the user-location depends on the existence of non-common or site-dependent errors, which occur at the points of observation and the reference. Of these, the most common and dominant site-dependent error is the multipath. Therefore, this research evaluates the effects of site-dependent errors on C/A code differential GPS correction accuracies by providing special emphasis on the multipath error. For the analyses, four segments of about 24-hour continuous static C/A code based DGPS observations were conducted at three precisely known ground stations and four different multipath environments were introduced by placing three different types of artificial signal reflectors at one of the observation stations. By using the known GPS receiver-reflector configuration, pseudo-range multipath was precisely calculated for each observation segment. C/A code DGPS positioning accuracies before and after multipath mitigation were presented by evaluating the effect of the most dominant site-dependent error, i.e., multipath, on C/A code DGPS correction accuracies.

scholarly journals Quality assessment of gas produced from different types of biomass pellets in gasification process

2019 ◽  
Vol 38 (2) ◽  
pp. 406-416 ◽  
Author(s):  
Marcel Mikeska ◽  
Jan Najser ◽  
Václav Peer ◽  
Jaroslav Frantík ◽  
Jan Kielar
Keyword(s):  
Gas Turbines ◽  
Combustion Engine ◽  
Calorific Value ◽  
Internal Combustion ◽  
Combustion Gas ◽  
Gas Cleaning ◽  
Gasification Process ◽  
Different Types ◽  
Before And After ◽  
Cleaning Technology

Gas from the gasification of pellets made from renewable sources of energy or from lower-quality fuels often contains a number of pollutants. This may cause technical difficulties during the gas use in internal combustion gas engines used for energy and heat cogeneration. Therefore, an adequate system of gas cleaning must be selected. In line with such requirements, this paper focuses on the characterization and comparison of gases produced from different types of biomass during gasification. The biomass tested was wood, straw, and hay pellets. The paper gives a detailed description and evaluation of the measurements from a fix-bed gasifier for the properties of the produced gases, raw fuels, tar composition, and its particle content before and after the cleaning process. The results of elemental composition, net calorific value, moisture, and ash content show that the cleaned gases are suitable for internal combustion engine-based cogeneration systems, but unsuitable for gas turbines, where a different cleaning technology would be needed.

scholarly journals Are the Acute Effects of THC Different in Aging Adults?

2021 ◽  
Vol 11 (5) ◽  
pp. 590
Author(s):  
Raeghan L. Mueller ◽  
Jarrod M. Ellingson ◽  
L. Cinnamon Bidwell ◽  
Angela D. Bryan ◽  
Kent E. Hutchison
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Age Groups ◽  
Young Group ◽  
Self Administration ◽  
Behavioral Measures ◽  
Younger Adults ◽  
Different Types ◽  
Before And After ◽  
Aging Adults

In recent years of expanding legalization, older adults have reported the largest increase in cannabis use of any age group. While its use has been studied extensively in young adults, little is known about the effects of THC in older adults and whether the risks of cannabis might be different, particularly concerning intoxication and cognition. The current study investigated whether age is associated with the deleterious effects of THC on cognitive performance and other behavioral measures before and after ad libitum self-administration of three different types of cannabis flower (THC dominant, THC + CBD, and CBD dominant). Age groups consisted of young adults (ages 21–25) and older adults (ages 55–70). Controlling for pre-use scores on all measures, the THC dominant chemovar produced a greater deleterious effect in younger adults compared with older adults in tests of learning and processing speed, whereas there were no differences between old and young in the effects of the other chemovars. In addition, the young group reported greater cannabis craving than the older group after using the THC chemovar. Consistent with some reports in the preclinical literature, the findings suggest that older adults may be less sensitive to the effects of THC on cognitive and affective measures.

Processing Techniques of a Silicon Carbide Heat Exchanger and its Capable Properties – A Review

2015 ◽  
Vol 787 ◽  
pp. 513-517 ◽  
Author(s):  
R. Pachaiyappan ◽  
R. Gopinath ◽  
S. Gopalakannan
Keyword(s):  
Silicon Carbide ◽  
Heat Exchanger ◽  
Gas Turbines ◽  
Cooling System ◽  
Composite Ceramic ◽  
Processing Technique ◽  
Full Potential ◽  
Absorption Chillers ◽  
Evaporative Cooling System ◽  
Processing Techniques

Silicon carbides is a composite ceramic material produced from inorganic non-metallic substances, formed from the molten mass which solidifies on cooling and simultaneously matured by the action of heat. It is used in various applications such as grinding wheels, filtration of gases and water, absorption, catalyst supports, concentrated solar powers, thermoelectric conversion etc. The modern usage of silicon carbide is fabricated as a heat exchanger for high temperature applications. Leaving behind steel and aluminium, silicon carbide has an excellent temperature withstanding capability of 1425°C. It is resistant to corrosion and chemical erosion. Modern fusion reactors, Stirling cycle based gas turbines, evaporators in evaporative cooling system for air condition and generator in LiBr/H2O absorption chillers for air conditioning those systems heat transfer rate can be improved by replacing a present heat exchanger with silicon carbide heat exchanger. This review presents a detailed discussion about processing technique of such a silicon carbide. Modern known processing techniques are partial sintering, direct foaming, replica, sacrificial template and bonding techniques. The full potential of these materials can be achieved when properties are directed over specified application. While eyeing over full potential it is highly dependent on processing techniques.

Human mobility models reveal the underlying mechanism of seasonal movements across China

2021 ◽  
Author(s):  
Bing Song ◽  
Xiao-Yong Yan ◽  
Suoyi Tan ◽  
Bin Sai ◽  
Shengjie Lai ◽  
...  
Keyword(s):  
Traffic Engineering ◽  
Human Mobility ◽  
Underlying Mechanism ◽  
Gravity Models ◽  
Mobility Models ◽  
Temporal And Spatial Distribution ◽  
Population Movements ◽  
Different Types ◽  
Before And After ◽  
Time Periods

Understanding the spatial interactions of human mobility is crucial for urban planning, traffic engineering, as well as for the prevention and control of infectious diseases. Although many models have been developed to model human mobility, it is not clear whether such models could also capture the traveling mechanisms across different time periods (e.g. workdays, weekends or holidays). With one-year long nationwide location-based service (LBS) data in China, we investigate the spatiotemporal characteristics of population movements during different time periods, and make thorough comparisons for the applicability of five state-of-the-art human mobility models. We find that population flows show significant periodicity and strong inequality across temporal and spatial distribution. A strong “backflow” effect is found for cross-city movements before and after holidays. Parameter fitting of gravity models reveals that travels in different type of days consider the attractiveness of destinations and cost of distance differently. Surprisingly, the comparison indicates that the parameter-free opportunity priority selection (OPS) model outperforms other models and is the best to characterize human mobility in China across all six different types of days. However, there is still an urgent need for development of more dedicated models for human mobility on weekends and different types of holidays.

scholarly journals Comparative Analysis of Capabilities of Different Types of Cone-Beam Tomography in an Experimental Study of Root Canals of Teeth Filled with High-Density Materials (part 2)

2021 ◽  
pp. 51-61
Author(s):  
A. Yu. Vasil'ev ◽  
V. V. Petrovskaya ◽  
E. A. Nichipor ◽  
V. G. Alpatova ◽  
N. N. Potrakhov ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Experimental Study ◽  
Cone Beam Computed Tomography ◽  
Comparative Assessment ◽  
High Density ◽  
Cone Beam ◽  
Root Canals ◽  
Different Types ◽  
Before And After ◽  
Cone Beam Tomography

During the course of this experimental study tomograms of extracted teeth were analyzed before and after filling the root canals with an endodontic material and fragments of broken metal instruments for root canal treatment. During the first stage of the experiment, untreated extracted teeth were scanned using conebeam computed tomography and microfocus cone-beam computed tomography. A comparative assessment of capabilities of the two methods of cone-beam computed tomography based on examination of untreated root canals was carried out. The second part of the study is dedicated to visualization of root canals that contain foreign high-density materials.

scholarly journals Do NiTi Instruments show Defects before Separation? Defects caused by Torsional Fatigue in Hand and Rotary Nickel-Titanium (NiTi) Instruments which Lead to Failure during Clinical Use

2012 ◽  
Vol 13 (6) ◽  
pp. 867-872 ◽  
Author(s):  
Sudhir Kumar ◽  
P Ratnakar ◽  
NV Murali Krishna Chakka ◽  
Sanjib Das ◽  
Anandamy Bagchi ◽  
...  
Keyword(s):  
Nickel Titanium ◽  
Clinical Use ◽  
New Classification ◽  
Torsional Fatigue ◽  
Anterior Teeth ◽  
Microscopic Evaluation ◽  
Different Types ◽  
Before And After ◽  
The Difference ◽  
Niti Instruments

ABSTRACT Aims Visual and microscopic evaluation of defects caused by torsional fatigue in hand and rotary nickel titanium (NiTi) instruments. Materials and methods Ninety-six NiTi greater taper instruments which were routinely used for root canal treatment only in anterior teeth were selected for the study. The files taken include ProTaper for hand use, ProTaper Rotary files and Endowave rotary files. After every use, the files were observed visually and microscopically (Stereomicroscope at 10×) to evaluate the defects caused by torsional fatigue. Scoring was given according to a new classification formulated which gives an indication of the severity of the defect or damage. Statistical analysis Data was statistically analyzed using KruskallWallis and Mann-Whitney U test. Results Number of files showing defects were more under stereomicroscope than visual examination. But, the difference in the evaluation methods was not statistically significant. The different types of defects observed were bent instrument, straightening/stretching of twist contour and partial reverse twisting. Endowave files showed maximum number of defects followed by ProTaper for hand use and least in ProTaper Rotary. Conclusion Visible defects due to torsional fatigue do occur in NiTi instruments after clinical use. Both visual and microscopic examinations were efficient in detecting defects caused due to torsional fatigue. This study emphasizes that all files should be observed for any visible defects before and after every instrumentation cycle to minimize the risk of instrument separation and failure of endodontic therapy. How to cite this article Chakka NVMK, Ratnakar P, Das S, Bagchi A, Kumar S, Anumula L. Do NiTi Instruments show Defects before Separation? Defects caused by Torsional Fatigue in Hand and Rotary Nickel-Titanium (NiTi) Instruments which Lead to Failure during Clinical Use. J Contemp Dent Pract 2012;13(6):867-872.

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