New Experimental Insights into the Bromate – 4-Aminophenol Photochemical Oscillations

2015 ◽  
Vol 229 (3) ◽  
Author(s):  
Jeffrey G. Bell ◽  
Jichang Wang
Keyword(s):  
Great Influence ◽  
Oscillatory System ◽  
Oscillatory Behavior ◽  
Continuous Illumination ◽  
Time Interval ◽  
Illumination Time ◽  
High Frequency Oscillations ◽  
Nonlinear Reaction ◽  
Time Period ◽  
Optimal Illumination

AbstractIn this research, it was found that following the photo-dissolution of the intermediate product N-bromo-1,4-benzoquinone-4-imine in the bromate – 4-aminophenol reaction, removal of illumination may allow the system to exhibit spontaneous chemical oscillations. This new observation complements the earlier report that the bromate – 4-aminophenol reaction could only oscillate under continuous illumination. Our exploration illustrates that the initial concentrations of bromate, 4-aminophenol and sulfuric acid have great influence on whether or not the system requires constant illumination for exhibiting oscillatory behavior. There is indeed an optimal illumination time interval at which the subsequently un-illuminated system would exhibit a large number of high frequency oscillations with or without an induction time period. Similar influences were also observed in the presence of cerium, in which the system exhibited sequential oscillations. Being able to respond to light in both a negative and constructive way makes this oscillatory system an attractive model for investigating perturbed nonlinear reaction dynamics.

Utilization of remote sensing for estimation of scale of cutting and growing of forest zones

2017 ◽  
Vol 920 (2) ◽  
pp. 57-60
Author(s):  
F.E. Guliyeva
Keyword(s):  
Remote Sensing ◽  
Fixed Time ◽  
Time Interval ◽  
Time Points ◽  
Average Value ◽  
Time Period ◽  
Remote Estimation ◽  
The Given ◽  
Forest Cutting

The study of results of relevant works on remote sensing of forests has shown that the known methods of remote estimation of forest cuts and growth don’t allow to calculate the objective average value of forests cut volume during the fixed time period. The existing mathematical estimates are not monotonous and make it possible to estimate primitively the scale of cutting by computing the ratio of data in two fixed time points. In the article the extreme properties of the considered estimates for deforestation and reforestation models are researched. The extreme features of integrated averaged values of given estimates upon limitations applied on variables, characterizing the deforestation and reforestation processes are studied. The integrated parameter, making it possible to calculate the averaged value of estimates of forest cutting, computed for all fixed time period with a fixed step is suggested. It is shown mathematically that the given estimate has a monotonous feature in regard of value of given time interval and make it possible to evaluate objectively the scales of forest cutting.

Research on Data Processing Method of Beacon Balloon

2014 ◽  
Vol 1030-1032 ◽  
pp. 1775-1778
Author(s):  
Hui Fen Li ◽  
Jian Wei He ◽  
Hong Yan Li ◽  
Zheng Xu Dai ◽  
Qing Ji
Keyword(s):  
Interval Data ◽  
Continuous Variable ◽  
Time Interval ◽  
Accuracy Evaluation ◽  
Time Period ◽  
Data Processing Method ◽  
Evaluation Test ◽  
Long Time ◽  
Accurate Comparison ◽  
Dynamic Time

Releasing beacon balloons is an effective way for space TT&C ship to obtain accurate comparison data and an important resource for accuracy evaluation. However, it is hard for theodolite to keep track beacon balloon stably for a long time. Its function has not been realized because the time period of the effective data is so short that it can not satisfy the request of traditional accuracy evaluation test. Aiming at this problem, this paper suggests an assumption of accuracy evaluation based on dynamic time interval non-continuous variable data. Utilizing self–adaptive outlier detection method and fitting residual error method, this paper solves the puzzle of dealing with dynamic time interval data which can not be treated by existing method, and realizes the self-determination of space TT&C ship accuracy evaluation test.

Robustness Metrics for Time-Dependent Quality Characteristics

2011 ◽  
Author(s):  
Xiaoping Du
Keyword(s):  
Design Optimization ◽  
Robust Design ◽  
Quality Characteristics ◽  
Time Dependent ◽  
Robust Design Optimization ◽  
Time Interval ◽  
Mechanism Analysis ◽  
Quality Loss ◽  
Time Period ◽  
Robustness Metrics

Quality characteristics (QC’s) are often treated static in robust design optimization while many of them are time dependent in reality. It is therefore desirable to define new robustness metrics for time-dependent QC’s. This work shows that using the robustness metrics of static QC’s for those of time-dependent QC’s may lead to erroneous design results. To this end, we propose the criteria of establishing new robustness metrics for time-dependent QC’s and then define new robustness metrics. Instead of using a point expected quality loss over the time period of interest, we use the expectation of the maximal quality loss over the time period to quantify the robustness for time-dependent QC’s. Through a four-bar function generator mechanism analysis, we demonstrate that the new robustness metrics can capture the full information of robustness of a time-dependent QC over a time interval. The new robustness metrics can then be used as objective functions for time-dependent robust design optimization.

scholarly journals Impact of Soiling Rate on Solar Photovoltaic Panel in Malaysia

2018 ◽  
Vol 225 ◽  
pp. 04008 ◽  
Author(s):  
Shaharin A. Sulaiman ◽  
M. Rosman M. Razif ◽  
Tan Dei Han ◽  
Samson M. Atnaw ◽  
S. Norazilah A. Tamili
Keyword(s):  
Prediction Model ◽  
Electrical Power ◽  
Time Interval ◽  
Solar Pv ◽  
Pv System ◽  
Photovoltaic Panel ◽  
Pv Panel ◽  
Time Period ◽  
Solar Pv System ◽  
Time Basis

There are some weaknesses of using solar PV system especially when there is issue of soiling on the surface of solar PV panel. The consequences for absence of this such study can cause unanticipated cost in the operation of solar PV panel. The objective of this project is to study the trend of soiling rate over different time period and its effect on the performance of solar PV panel in Malaysia and to develop a simple prediction model for cleaning interval of solar PV system in Malaysia. The study was conducted on real-time basis on a building’s roof. Measurements of solar irradiance, voltage, current and the mass of dust collected were performed from both clean and dirty panels. It was discovered that the Monthly Test was significant with 4.53% of performance drop. Further analysis was conducted by running prediction model for cleaning interval. Intersection of graph plotting and fixed cleaning cost gives answer of cleaning interval that can be performed. It can be concluded that for every two and half month is the recommended time interval to perform regular cleaning to maximise electrical power generation by solar PV system in Malaysia.

scholarly journals The impact of African aridity on the isotopic signature of Atlantic deep waters across the Middle Pleistocene Transition

2012 ◽  
Vol 77 (1) ◽  
pp. 182-191 ◽  
Author(s):  
Bruno Malaizé ◽  
Elsa Jullien ◽  
Amandine Tisserand ◽  
Charlotte Skonieczny ◽  
E. Francis Grousset ◽  
...  
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Environmental Changes ◽  
Phase Relationship ◽  
Isotopic Signature ◽  
Middle Pleistocene ◽  
Time Interval ◽  
Deep Waters ◽  
Time Period ◽  
The Impact

A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~ 1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0–0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ18O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass δ13C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ13C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ13C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ18O and δ13C values of deep waters.

scholarly journals Renewed methane increase for five years (2007–2011) observed by solar FTIR spectrometry

2012 ◽  
Vol 12 (11) ◽  
pp. 4885-4891 ◽  
Author(s):  
R. Sussmann ◽  
F. Forster ◽  
M. Rettinger ◽  
P. Bousquet
Keyword(s):  
Time Series ◽  
Confidence Interval ◽  
Global Scale ◽  
Future Trend ◽  
Time Interval ◽  
Positive Trend ◽  
Time Period ◽  
New Period ◽  
Natural Wetlands ◽  
Surface Network

Abstract. Trends of column-averaged methane for the time period (1996, Sep 2011) are derived from the mid-infrared (mid-IR) solar FTIR time series at the Zugspitze (47.42° N, 10.98° E, 2964 m a.s.l.) and Garmisch (47.48° N, 11.06° E, 743 m a.s.l.). Trend analysis comprises a fit to the de-seasonalized time series along with bootstrap resampling for quantifying trend uncertainties. We find a positive trend during [1996, 1998] of 9.0 [3.2, 14.7] ppb yr−1 for Zugspitze (95% confidence interval), an insignificant growth during [1999, mid 2006] of 0.8 [−0.1, 1.7] ppb yr−1 (Zugspitze), and a significant renewed increase during [mid 2006, Sep 2011] of 5.1 [4.2, 6.0] ppb yr−1 for Garmisch, which is in agreement with 4.8 [3.8, 5.9] ppb yr−1 for Zugspitze. The agreement of methane trends at the two closely neighboring FTIR sites Zugspitze and Garmisch within the uncertainties indicates a good station-to-station consistency as a basis for future trend analyses by the ground-based mid-IR FTIR network on the global scale. Furthermore, the Zugspitze FTIR trend for the time interval [Jul 2006, Jun 2009] is found to agree with the trend derived from SCIAMACHY (WFM-DOAS v2.0.2) data within the 95% confidence intervals. In case a 1000-km pixel selection radius around the Zugspitze is used, the confidence interval is narrower for the FTIR trend (6.9 [4.2, 9.5] ppb yr−1) compared to SCIAMACHY (7.1 [5.1, 8.6] ppb yr−1). If, however, a loosened pixel selection is used (≈1000-km half-width latitudinal band), the SCIAMACHY trend significance interval is narrower (6.8 [5.1, 8.6] ppb yr−1) compared to Zugspitze FTIR (5.7 [3.0, 8.3] ppb yr−1). While earlier studies using surface network data revealed changes of 8.0 ± 0.6 ppb in 2007, 6.4 ± 0.6 ppb in 2008, and 4.7 ± 0.6 ppb in 2009 (Dlugokencky et al., 2011), our updated result proves that the renewed methane increase meanwhile has been persisting for >5 years [mid 2006, Sep 2011]. This is either the longest and largest positive trend anomaly since the beginning of systematic observations more than 25 years ago or the onset of a new period of strongly increasing CH4 levels in the atmosphere. Several scenarios have been developed to explain the persistent increase observed, mainly invoking an increase in emissions from natural wetlands, an increase in fossil fuel-related emissions or a decrease in OH concentrations. However, more work is needed to fully attribute this increase to a particular source or sink.

A warmer Mediterranean region at the Miocene to Pliocene transition

2020 ◽  
Author(s):  
Iuliana Vasiliev ◽  
Daniela Boehn ◽  
Darja Volkovskaja ◽  
Clemens Schmitt ◽  
Konstantina Agiadi ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Mediterranean Basin ◽  
Mediterranean Region ◽  
Elevated Temperatures ◽  
Sea Water ◽  
Time Interval ◽  
Time Period ◽  
Organic Biomarkers ◽  
The Mediterranean ◽  
D Values

<p>Between 5.97-5.33 Ma several kilometre-thick evaporite units were deposited in the Mediterranean Basin during the Messinian Salinity Crisis (MSC). The MSC reflects a period featured by a negative hydrological budget, with a net evaporative loss of water exceeding precipitation and riverine runoff. The contemporary changes in continental and marine circum-Mediterranean temperature are, however, poorly constrained. Here we reconstruct continental mean annual temperatures (MAT) using branched glycerol dialkyl glycerol tetraether (GDGT) biomarkers for the time period corresponding to MSC Stage 3 (5.55-5.33 Ma). Additionally, for the same time interval, we estimate sea surface temperatures (SSTs) of the Mediterranean Sea using isoprenoidal GDGTs based TEX<sub>86</sub> proxy. The excellently preserved organic biomarkers were extracted from outcrops and DSDP cores spread over a large part of the onland (Malaga, Sicily, Cyprus) and offshore (holes 124 and 134 from the Balearic abyssal plane and hole 374 from the Ionian Basin) Mediterranean Basin domain. The calculated MATs for the 5.55 to 5.33 Ma interval show values around 16 to 18 ºC for the Malaga, Sicily and Cyprus outcrops. The MAT values calculated for DSDP Leg 13 holes 124, 134 and Leg 42A hole 374 are lower, around 11 to 13 ºC.</p><p>For samples where the branched and isoprenoid tetraether (BIT) index was lower than the 0.4 we could calculate TEX<sub>86</sub> derived SSTs averaging around 27 ºC for all sampled locations. Where available (i.e. Sicily), we compared the TEX<sub>86</sub> derived SSTs with alkenone based, U<sup>k</sup><sub>37</sub> derived SST estimates from the same samples. The TEX<sub>86</sub> derived SST values are slightly higher than the U<sup>k</sup><sub>37</sub> derived SST of 20 to 28 ºC. For the Mediterranean region, values between 19 and 27 ºC of the U<sup>k</sup><sub>37</sub> derived SSTs were calculated for the interval between the 8.0 and 6.4 Ma (Tzanova et al., 2015), close to our calculations for Sicily section (20 to 28 ºC). Independent of common pitfalls that may arise in using molecular biomarkers as temperature proxies, both SST estimates independently hint towards much warmer Mediterranean Sea water during the latest phase (Stage 3) of the MSC. These elevated temperatures coincide with higher δD values measured on alkenones and long chain n-alkanes (both records indicating for more arid and/or warmer conditions than today between 5.55 and 5.33 Ma). We therefore conclude that the climate between 5.55 to 5.33 Ma was warmer than present-day conditions, recorded both in the Mediterranean Sea and the land surrounding it.</p>

Mathematical models for simulating Covid-19 contagion in Italy: first wave

2020 ◽  
Vol 6 (1) ◽  
pp. 39
Author(s):  
David Carf`ı ◽  
Alessia Donato
Keyword(s):  
Mathematical Models ◽  
Time Interval ◽  
First Derivative ◽  
Time Period

In this paper, we provide two approximating functions for some dynamics associated with the first wave of Covid-19 contagion in Italy. We consider also two particular cases of Sicily and Lombardy. We consider only the evolution of total infected cases and new daily cases. We show that the total infected cases need, in the time period considered, two different approximations. We approximate the daily infected curves by the first derivative of the above two functions. In the case of Lombardy, we consider a wider time interval to obtain an ultimate approximation.

Utilizing network quality committees to improve reporting and adherence to evidence-based clinical pathways.

2012 ◽  
Vol 30 (34_suppl) ◽  
pp. 76-76
Author(s):  
Debra A. Patt ◽  
J. Russell Hoverman ◽  
Gay Lindsey ◽  
Deedra Jastrzembski ◽  
Cynthia Taniguchi ◽  
...  
Keyword(s):  
Clinical Pathways ◽  
Time Interval ◽  
Evidence Based ◽  
Large Network ◽  
Time Period ◽  
Community Oncology ◽  
Improve Compliance ◽  
Value Based Care ◽  
Based Medicine

76 Background: In an era of evidence based medicine, several different evidence based pathways for cancer treatment exist. Few, however, contain decision support, are implemented into an electronic health record (EHR) or have demonstrated their effectiveness to provide value-based care. Providing systems to make a Pathways program operational and improve adherence supports a culture of value-based care. Methods: Physician designed evidence based pathways for a large network of community oncologists was rolled out over a statewide practice. A team of pharmacists and data managers designed a program to support implementation of this pathways initiative. Physician-led quality committees were created at the practice level to troubleshoot and characterize the process of making adherence operational and improving upon other quality metrics, variance reporting, and patient satisfaction. Treatments were charted in the EHR and available for reporting. Documentation of rationale for off-pathway exceptions was also captured. Assessable data, adherence, and exception documentation were measured prior to the onset of the committees and again with follow-up for 1 year after initiation of the committees from March 2011 through February 2012. Results: Within this large practice of 342 physicians, there were 39 quality committees created. During this time assessable data, adherence, and justification of exceptions to evidence-based pathways changed. At the beginning of the time period, assessable data was 84% and improved to 90% after a year. Adherence to pathways was 60% and improved to 68% over the same time interval. Exception documentation also improved from 14% to 25%. Conclusions: Formalizing an internal physician-driven operational procedure to improve upon quality can increase the reporting and adherence to physician created evidence-based pathways across a network of community oncologists and moves to change a culture of value-based excellence within community oncology practices. Continuous and internally driven adherence to value-based metrics improve compliance over time. Internal systems such as these are essential to make evidence-based pathways operational.

scholarly journals Fitting growth models to length frequency data

2004 ◽  
Vol 61 (2) ◽  
pp. 218-230 ◽  
Author(s):  
Geoff M. Laslett ◽  
J. Paige Eveson ◽  
Tom Polacheck
Keyword(s):  
Growth Models ◽  
Time Interval ◽  
Age Group ◽  
Frequency Data ◽  
Sampling Errors ◽  
Length Frequency ◽  
Error Structure ◽  
Second Stage ◽  
Time Period ◽  
Length Frequency Data

Abstract A novel two-stage procedure for fitting growth curves to length frequency data collected from commercial fisheries is described. The method is suitable for species in which cohorts are spawned over a limited time period, and samples of length frequency data are collected regularly (e.g. in weekly, fortnightly, or monthly time intervals) over an extended time period. In the first stage of analysis, Gaussian mixtures are fitted separately to the data for each time interval, and summary statistics (component means and standard errors) are extracted. In the second stage, parametric growth models, such as the von Bertalanffy seasonal growth curve, are fitted to the summary data. The error structure in this second stage of analysis incorporates random between-year effects, random within-year age-group effects, random within-year time-interval effects, random within-year age-group and time-interval interactions, and sampling errors. This complex error structure incorporating unbalanced crossed and nested random effects acknowledges that commercial fishing is not an exercise in random sampling, and allows for the inevitable additional sources of random variation in such an enterprise. The method is applied to South Australian southern bluefin tuna length frequency data collected from 1964 to 1989, and leads to the conclusion that juvenile tuna grew faster in the 1980s than in the 1960s, with the 1970s being a decade of highly variable growth.

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