scholarly journals Diacetyl and Other Ketones in e-Cigarette Aerosols: Some Important Sources and Contributing Factors

2021 ◽  
Vol 9 ◽  
Author(s):  
Kevin McAdam ◽  
Gareth Waters ◽  
Serban Moldoveanu ◽  
Jennifer Margham ◽  
Anthony Cunningham ◽  
...  
Keyword(s):  
Respiratory Diseases ◽  
Primary Source ◽  
Thermal Reduction ◽  
Operating Conditions ◽  
Direct Transfer ◽  
Contributing Factors ◽  
Thermal Generation ◽  
Decomposition Reactions ◽  
Ring Compounds ◽  
Low Levels

Background: Concerns over the presence of the diketones 2,4 butanedione (DA) and 2,3 pentanedione (AP) in e-cigarettes arise from their potential to cause respiratory diseases. Their presence in e-liquids is a primary source, but they may potentially be generated by glycerol (VG) and propylene glycol (PG) when heated to produce aerosols. Factors leading to the presence of AP, DA and acetoin (AC) in e-cigarette aerosols were investigated. We quantified direct transfer from e-liquids, examined thermal degradation of major e-liquid constituents VG, PG and 1,3 propanediol (1,3 PD) and the potential for AC, AP and DA production from sugars and flavor additives when heated in e-cigarettes.Method: Transfers of AC, AP and DA from e-liquids to e-cigarette aerosols were quantified by comparing aerosol concentrations to e-liquid concentrations. Thermal generation from VG, PG or 1,3 PD e-liquids was investigated by measuring AC, AP and DA emissions as a function of temperature in an e-cigarette. Thermal generation of AC, AP and DA from sugars was examined by aerosolising e-liquids containing sucrose, fructose or glucose in an e-cigarette. Pyrolytic formation of AP and DA from a range of common flavors was assessed using flash pyrolysis techniques.Results: AC transfer efficiency was >90%, while AP and DA were transferred less efficiently (65%) indicating losses during aerosolisation. Quantifiable levels of DA were generated from VG and PG, and to a lesser extent 1,3 PD at coil temperatures >300°C. Above 350°C AP was generated from VG and 1,3 PD but not PG. AC was not generated from major constituents, although low levels were generated by thermal reduction of DA. Aerosols from e-liquids containing sucrose contained quantifiable (>6 ng/puff) levels of DA at all sucrose concentrations tested, with DA emissions increasing with increasing device power and concentration. 1% glucose, fructose or sucrose e-liquids gave comparable DA emissions. Furanose ring compounds also generate DA and AP when heated to 250°C.Conclusions: In addition to less than quantitative direct transfer from the e-liquid, DA and AP can be present in the e-cigarette aerosol due to thermal decomposition reactions of glycols, sugars and furanonse ring flavors under e-cigarette operating conditions.

Effect of Film Cooling on Low Temperature Hot Corrosion in a Coal Fired Gas Turbine

2003 ◽  
Author(s):  
Vaidyanathan Krishnan ◽  
J. S. Kapat ◽  
Y. H. Sohn ◽  
V. H. Desai
Keyword(s):  
Low Temperature ◽  
Corrosion Rate ◽  
Hot Corrosion ◽  
Film Cooling ◽  
Gas Turbines ◽  
Primary Source ◽  
Operating Conditions ◽  
Coal Gas ◽  
A Chain ◽  
Lower Corrosion Rate

In recent times, the use of coal gas in gas turbines has gained a lot of interest, as coal is quite abundant as a primary source of energy. However, use of coal gas produces a few detrimental effects that need closer attention. This paper concentrates on one such effect, namely hot corrosion, where trace amounts of sulfur can cause corrosion (or sulfidation) of hot and exposed surfaces, thereby reducing the life of the material. In low temperature hot corrosion, which is the focus of this paper, transport of SO2 from the hot gas stream is the primary process that leads to a chain of events, ultimately causing hot corrosion. The corrosion rate depends on SO2 mass flux to the wall as well as wall surface temperature, both of which are affected in the presence of any film cooling. An analytical model is developed to describe the associated transport phenomena of both heat and mass in the presence of film cooling The model predicts how corrosion rates may be affected under operating conditions. It is found that although use of film cooling typically leads to lower corrosion rate, there are combinations of operating parameters under which corrosion rate can actually increase in the presence of film cooling.

Tangguh Project: Multidisciplinary and Challenging Design of a Novel Concept of Buckle Initiator

2021 ◽  
Author(s):  
Formentini Federico ◽  
Luigi Foschi ◽  
Filippo Guidi ◽  
Ester Iannucci ◽  
Lorenzo Marchionni ◽  
...  
Keyword(s):  
Soil Liquefaction ◽  
Operating Conditions ◽  
Contributing Factors ◽  
Operating Life ◽  
Foundation Design ◽  
Production Pipeline ◽  
Offshore Pipeline ◽  
Design Loads ◽  
Pipeline Route ◽  
Novel Concept

Abstract This paper is based on the experience made during the design and installation of an offshore pipeline recently completed in Indonesia, where a 24” subsea production pipeline (16km long in 70m water depth) was found susceptible during design to lateral buckling. To limit the development of excessive deformation within the acceptance criteria, a mitigation strategy based on interacting planned buckles has been adopted installing three Buckle Initiators (BI) along the pipeline route. Buckling is a well understood phenomenon. However, this project was characterized by major uncertainties mainly driven by soil characterization, soil-pipe interaction, seabed mobility and soil liquefaction. These uncertainties have played a key role in the in-service buckling design. A lot of engineering efforts have been spent to go through the screening between alternative concepts, the validation of the chosen solution and its detailed engineering phase. This paper discusses the main contributing factors and how the uncertainties have been tackled. The Buckle Initiators are quite large and heavy structures with two main bars: the first ramp has an inclination equal to 30° and the pipeline has been laid on it; a second horizontal ramp was used as sleeper to accommodate the development of the lateral buckle during the operating life. A rotating arm was also used to restrict the pipeline lay corridor on the inclined ramp guaranteeing a combined horizontal and vertical out-of-straightness in the as-laid configuration. The rotating arm has been released as soon as the pipeline passed the BI permitting the pipeline to slide freely over the two BI ramps. The foundation of the Buckle Initiator has a footprint surface of about 60m2 guaranteeing its stability for different soil types characterizing the three installation areas. This more complex solution was preferred with respect to a typical sleeper to increase the robustness of the system in terms of buckle mobilization. The design of the Buckle Initiator was a multidisciplinary activity where many novel concepts were developed and many issues were faced (i.e. pipeline laying on an inclined sleeper, anti-scouring system, foundation design, etc.). The Buckle Initiator design was focused on structural calculations against design loads expected during temporary and operating conditions, geotechnical verifications, installation analysis, pipeline configuration and fatigue assessment. This paper presents all main engineering aspects faced during design and first feedbacks from field after the pipeline installation.

scholarly journals Design and Simulation of a Capless Low Drop Out Voltage Regulator

2021 ◽  
pp. 69-75
Author(s):  
Babitha S ◽  
Mr. Hemanth Naidu K J ◽  
Mr. Ashwin Goutham G ◽  
Mr. Harshith S V
Keyword(s):  
High Performance ◽  
Primary Source ◽  
Operating Conditions ◽  
Drop Out ◽  
Voltage Regulator ◽  
Portable Devices ◽  
Current Amplifier ◽  
Power Resources ◽  
Error Amplifier ◽  
The Stability

Portable electronic devices mostly used battery as their primary source for operation hence longer running batteries or Power resources or vital for any portable device need for stable voltage supplies have led to the development of low dropout voltage regulators low dropout regulators provide stable regulated output voltage in various operating conditions which makes it useful in portable devices that design of high performance and stable low dropout voltage regulator is a challenge nowadays with decreasing device size and increasing power densities. The proposed circuit used a 5pack architecture of error amplifier. This paper proposes the study of behavior of the LDO voltage regulator with internal capacitors i.e., capless. The regulated voltage of 1.8V is obtained using the typical power supply of 2.2V obtained dropout voltage of 400mv with the delay of 12.77micro sec, power consumed 1.816W. The proposed design produced DC gain of 31.77db,with the load current variation of 0 to 20mA. The capless LDO architecture is verified in the Cadence 180nm technology. The architecture provides a stable gain and plot for both Temperature and Load Variations. The stability issues are overcome using the compensation techniques which uses a current amplifier and a capacitor in the differentiator configuration. The current amplifier implemented uses current mirror with current copying ratio of unity.

scholarly journals Reliability of the Determinations of Polychlorinated Contaminants (Biphenyls, Dioxins, Furans)

1996 ◽  
Vol 79 (3) ◽  
pp. 589-621 ◽  
Author(s):  
William Horwitz ◽  
Richard Albert
Keyword(s):  
Performance Studies ◽  
Detection System ◽  
Operating Conditions ◽  
Mass Spectrometers ◽  
Common Reference ◽  
Ring Compounds ◽  
Interlaboratory Variability ◽  
Dioxins And Furans ◽  
Relative Standard ◽  
Good Laboratory

Abstract Precision performance parameters from results of 34 interlaboratory performance studies of polychlorinated aromatic ring compounds (biphenyls, dioxins, and furans) (PCCs) have been recalculated by using the International Union of Pure and Applied Chemistry-1987 harmonized protocol. Most studies of 1052 test samples, 56 analytes, 19 matrixes, and 2 types of detectors (electron capture and mass spectrometers) provide among-laborato- ries relative standard deviations (RSDRs), that are considerably better than those predicted from the Horwitz equation at fractional concentrations of 10−6 down to 10−15. The explanation suggested is that supplying common reference calibration solutions, as was done in many of these studies, does not reflect realistic operating conditions. Furthermore, the ability to repeat, discuss, and reassess aberrant reported values results in underestimating the true RSDR. The commonly reported problems of preparation of standard calibrating solutions, instability of the detection system, and failure to follow quality control instructions and good laboratory practices may be important sources of interlaboratory variability in PCC determinations

On-line determination of nitrite in wastewater treatment by use of a biosensor

2002 ◽  
Vol 45 (4-5) ◽  
pp. 69-76 ◽  
Author(s):  
M. Nielsen ◽  
N.P. Revsbech ◽  
L.H. Larsen ◽  
A. Lynggard-Jensen
Keyword(s):  
Activated Sludge ◽  
Mechanical Damage ◽  
Operating Conditions ◽  
Bacterial Populations ◽  
Operational Lifetime ◽  
On Line ◽  
Low Levels ◽  
In The Beginning

A newly developed biosensor for nitrite having a 90% response time of about 1 min was used to monitor nitrite concentration in activated sludge exposed to oxic/anoxic cycles. The NO2− biosensor contains bacteria that reduce NO2−, but not NO3−, to N2O that is subsequently monitored by a built-in electrochemical sensor. Nitrite plus nitrate (NOx−) was simultaneously monitored by a NOx− biosensor. The maximum operational lifetime of the NO2− biosensor was 6 weeks, but much longer lifetimes can be expected as malfunctioning by the 3 sensors used for longer periods was due to either mechanical damage or ineffective internal sterilization during the construction. Insufficiently sterilized sensors became sensitive also to NO3− after some time due to development of NO3−-reducing bacterial populations within the sensor. The fraction of NO2− as compared to NO3− in the activated sludge was very dependent on prehistory, actual loading, and aeration. During balanced operation with NH4+ being exhausted during the later parts of the aerobic cycle, NO2− increased in concentration up to about 50 μM during the early part of the aeration cycle until NH4+ became limiting. At that time the NO2− concentration decreased to low levels. Under some operating conditions a peak of NO2− also appeared in the beginning of the anoxic period. NO2− and NO3− were depleted simultaneously during the anoxic period.

High Frequency Inversion Capacitance Measurements for 6H-SiC n-MOS Capacitors from 450 to 600 °C

2008 ◽  
Vol 600-603 ◽  
pp. 739-742 ◽  
Author(s):  
Ruby N. Ghosh ◽  
Reza Loloee ◽  
Tamara Isaacs-Smith ◽  
John R. Williams
Keyword(s):  
High Frequency ◽  
Operating Conditions ◽  
Oxide Semiconductor ◽  
Electrical Characteristics ◽  
Physical Processes ◽  
Large Area ◽  
Thermal Generation ◽  
Mos Capacitors ◽  
Mos Devices ◽  
Minority Carriers

The operation of metal-oxide-semiconductor (MOS) devices based on the semiconductor SiC in high temperature environments above 300 °C requires an understanding of the physical processes in these capacitor structures under operating conditions. In this study we have focused on the regime of inversion biasing, where the electrical characteristics of the device are dominated by minority carriers. We report on the direct observation of the high frequency inversion capacitance due to thermal generation of holes in 6H-SiC n-MOS capacitors between 450 and 600 °C by monitoring the 1MHz C-V characteristics of large area, 1000 μm diameter, capacitors in the dark. Our experimental results are consistent with a first order calculation based on the delta depletion approximation.

Laboratory Simulation of Pentachlorophenol / Phenate Behaviour in an Alluvial Aquifer

1987 ◽  
Vol 22 (1) ◽  
pp. 147-156 ◽  
Author(s):  
R.J. Patterson ◽  
H.M. Liebscher
Keyword(s):  
Early Stage ◽  
Low Cost ◽  
Field Tests ◽  
Field Studies ◽  
Alluvial Aquifer ◽  
Operating Conditions ◽  
Laboratory Simulation ◽  
Retardation Factor ◽  
Site Assessment ◽  
Low Levels

Abstract In 1978, about 18,000 litres of a chlorophenol/phenate solution leaked from a sawmill dip tank located approximately 120 metres from the Okanagan River in Penticton, B.C. Results of field studies indicated that the chlorophenol/phenate migrated through a surficial alluvial aquifer toward the river and that the retardation factor for the contaminants was between 1,05 and 1.43. A purge we 11 remedial operation recovered only about 40% of the spilled chlorophenol/phenate. More than five years after the purging operation, low levels of chlorophenol/phenate were still present in the groundwater. A column test to simulate the subsurface transport and purging behaviour of pentachlorophenol/phenate was conducted in the laboratory under conditions which duplicated, as closely as possible, those in the field. Results, which suggest a retardation factor of about 1.25 and non-equilibrium (i.e. slow) sorption/desorption, can account for the behaviour of the contaminants in the aquifer under natural flow conditions and during purging. The success achieved in the simulation indicates that these types of tests can be applied usefully in the study of contaminant behaviour in the subsurface. In addition, they could play an important role in waste site assessment and remediation programs where purging is an alternative. Data can be obtained at relatively low cost and at an early stage in an investigation, and could be employed to provide a preliminary assessment of the probable efficiency of purging. Moreover, the results could be applied to establish parameters and operating conditions that will improve the effectiveness of costly field tests that must precede the design of an optimal purging system.

Evaluation of Advanced Combustors for Dry NOx Suppression With Nitrogen Bearing Fuels in Utility and Industrial Gas Turbines

1982 ◽  
Vol 104 (2) ◽  
pp. 429-438 ◽  
Author(s):  
M. B. Cutrone ◽  
M. B. Hilt ◽  
A. Goyal ◽  
E. E. Ekstedt ◽  
J. Notardonato
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Water Injection ◽  
Operating Conditions ◽  
Department Of Energy ◽  
Technical Program ◽  
Wide Range ◽  
Industrial Gas Turbines ◽  
Low Levels

The work described in this paper is part of the DOE/LeRC Advanced Conversion-Technology Project (ACT). The program is a multiple contract effort with funding provided by the Department of Energy, and technical program management provided by NASA LeRC. Combustion tests are in progress to evaluate the potential of seven advanced combustor concepts for achieving low NOx emissions for utility gas turbine engines without the use of water injection. Emphasis was on the development of the required combustor aerothermodynamic features for burning high nitrogen fuels. Testing was conducted over a wide range of operating conditions for a 12:1 pressure ratio heavy-duty gas turbine. Combustors were evaluated with distillate fuel, SRC-II coal-derived fuel, residual fuel, and blends. Test results indicate that low levels of NOx and fuel-bound nitrogen conversion can be achieved with rich-lean combustors for fuels with high fuel-bound nitrogen. In addition, ultra-low levels of NOx can be achieved with lean-lean combustors for fuels with low fuel-bound nitrogen.

scholarly journals Assessing Gaming Simulation Validity for Training Traffic Controllers

2016 ◽  
Vol 48 (2) ◽  
pp. 219-235 ◽  
Author(s):  
G. van Lankveld ◽  
E. Sehic ◽  
J. C. Lo ◽  
S. A. Meijer
Keyword(s):  
Large Scale ◽  
Social Impact ◽  
Operating Conditions ◽  
Minimum Level ◽  
Railway Company ◽  
Gaming Simulation ◽  
Rail Infrastructure ◽  
Simulation Session ◽  
Low Levels ◽  
New Infrastructure

Background. The Dutch railway company ProRail is performing large-scale capacity upgrades to their infrastructure network. As part of these upgrades, ProRail uses gaming simulations to help prepare train traffic controllers for new infrastructure situations. Researching the validity of these gaming simulations is essential, since the conclusions drawn from gaming simulation use may result in decisions with large financial and social impact for ProRail and Dutch train passengers. Aim. In this article, we aim to investigate the validity of the gaming simulations for training traffic controllers for new situations in rail infrastructure. We also aim to contribute to the discussion on the minimum level of fidelity required to develop and conduct gaming simulations in a valid way. Method. We investigate the validity by using training sessions in conjunction with questionnaires. We based the approach and questionnaires on the earlier work of Raser. Results. Our results show that the validity of the gaming simulation ranges from medium to good. They also show that while the fidelity of the gaming simulation is not like the real-world operating conditions, this does not reduce validity to low levels. Conclusions. We conclude that the gaming simulation used in this study was of medium to good validity. We also conclude that maximum fidelity is not required in order to run a valid gaming simulation session.

Pressure Measurements and Flow Visualization in a Squeeze Film Damper Operating With a Bubbly Mixture

2001 ◽  
Vol 124 (2) ◽  
pp. 346-350 ◽  
Author(s):  
Luis San Andre´s ◽  
Sergio E. Diaz
Keyword(s):  
Flow Field ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Air Entrapment ◽  
Time Dynamic ◽  
Squeeze Film Dampers ◽  
Control Dynamic ◽  
Low Levels ◽  
And Control ◽  
First Time

Squeeze film dampers (SFDs) reduce rotor vibrations and control dynamic instabilities in turbomachinery. Depending on damper geometry and operating conditions, the kinematics of journal motion can induce air ingestion and entrapment, produce lubricant vapor cavitation, or both. Air ingestion is the most common condition found in open ended dampers due to the low levels of external pressurization used in practice. The degrading effect of air entrapment on damper performance not only defies predictive models but also constrains the design of SFDs to a costly trial and error process based on prior experience. The present measurements correlate for the first time dynamic squeeze film pressures and pictures of the flow field with the air volume content in the lubricant mixture of a damper performing circular centered motion. The photographs of the flow field at key instances of journal motion show the development of a non-homogeneous flow with large striated cavities of air that persist even in the regions of positive (above ambient) dynamic pressures.

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