29 research outputs found
A decision support methodology for process in the loop optimisation
Experimental optimisation with hardware-in-the-loop is a common procedure in engineering, particularly in cases where accurate modelling is not possible. A common methodology to support experimental search is to use one of the many gradient descent methods. However, even sophisticated and proven methodologies such as Simulated Annealing (SA) can be significantly challenged in the presence of significant noise. This paper introduces a decision support methodology based upon Response Surfaces (RS), which supplements experimental management based on variable neighbourhood search, and is shown to be highly effective in directing experiments in the presence of significant signal to noise (S-N) ratio and complex combinatorial functions. The methodology is developed on a 3-dimensional surface with multiple local-minima and large basin of attraction, and high S-N ratio. Finally, the method is applied to a real-life automotive experimental application
Scheduling of grid tied battery energy storage system participating in frequency response services and energy arbitrage
Battery energy storage
systems
(BESS)
are
widely used to smooth
power
fluctuations
and maintain the voltage and
frequency of the power feeder at a desired level.
T
he National Grid Electricity Transmission (NGET), the primary electricity
transmission network operator in the UK, has introduced various frequency response servic
es that are
designed
to provide a
real
-
time response to deviations in the grid frequency.
In this study
,
a
control
algorithm is
developed
which generates a
charge/discharge power output with respect to deviations in
the grid frequency and the requisite
service
specifications. Using
historical
UK electricity prices, a new
balancing
service scheduling approach
has
also been
developed to
maximize
energy
arbitrage
revenue
by layering
different types of balancing services
throughout the day
. Simulation result
s show that the
proposed algorithm delivers both dynamic and non
-
dynamic firm frequency response (FFR) and also enhanced frequency
response (EFR) to
NGET
specifications while
generating arbitrage revenue
as well as service availability payment
s
in the
balancing market. A comparative study is also presented to compare the yearly arbitrage revenue
obtained
from
the work
presented in this
paper and
a
previous
reference study
.
Finall
y, exper
imental results of
a
grid
-
tied
2MW
/1MWh
BESS
have
been used
for verification purposes
A Genome-Wide Association Study of Total Bilirubin and Cholelithiasis Risk in Sickle Cell Anemia
Serum bilirubin levels have been associated with polymorphisms in the UGT1A1 promoter in normal populations and in patients with hemolytic anemias, including sickle cell anemia. When hemolysis occurs circulating heme increases, leading to elevated bilirubin levels and an increased incidence of cholelithiasis. We performed the first genome-wide association study (GWAS) of bilirubin levels and cholelithiasis risk in a discovery cohort of 1,117 sickle cell anemia patients. We found 15 single nucleotide polymorphisms (SNPs) associated with total bilirubin levels at the genome-wide significance level (p value <5×10−8). SNPs in UGT1A1, UGT1A3, UGT1A6, UGT1A8 and UGT1A10, different isoforms within the UGT1A locus, were identified (most significant rs887829, p = 9.08×10−25). All of these associations were validated in 4 independent sets of sickle cell anemia patients. We tested the association of the 15 SNPs with cholelithiasis in the discovery cohort and found a significant association (most significant p value 1.15×10−4). These results confirm that the UGT1A region is the major regulator of bilirubin metabolism in African Americans with sickle cell anemia, similar to what is observed in other ethnicities
Is (poly-) substance use associated with impaired inhibitory control? A mega-analysis controlling for confounders.
Many studies have reported that heavy substance use is associated with impaired response inhibition. Studies typically focused on associations with a single substance, while polysubstance use is common. Further, most studies compared heavy users with light/non-users, though substance use occurs along a continuum. The current mega-analysis accounted for these issues by aggregating individual data from 43 studies (3610 adult participants) that used the Go/No-Go (GNG) or Stop-signal task (SST) to assess inhibition among mostly "recreational" substance users (i.e., the rate of substance use disorders was low). Main and interaction effects of substance use, demographics, and task-characteristics were entered in a linear mixed model. Contrary to many studies and reviews in the field, we found that only lifetime cannabis use was associated with impaired response inhibition in the SST. An interaction effect was also observed: the relationship between tobacco use and response inhibition (in the SST) differed between cannabis users and non-users, with a negative association between tobacco use and inhibition in the cannabis non-users. In addition, participants' age, education level, and some task characteristics influenced inhibition outcomes. Overall, we found limited support for impaired inhibition among substance users when controlling for demographics and task-characteristics
Clinical microbiology made ridiculously simple/ Gladwin
vi, 273 hal: ill; 26 c
Clinical microbiology made ridiculously simple/ Gladwin
vi, 273 hal: ill; 26 c
Clinical microbiology made ridiculously simple/ Gladwin
vi, 273 hal: ill; 26 c
Quasi-constant volume (QCV) spark ignition combustion
The Otto cycle delivers theoretical maximum thermal efficiency. The traditional design of internal combustion engines using a simple slide-crank mechanism gives no time for a constant volume combustion which significantly reduces the cycle efficiency. In this study, using a high torque, high bandwidth, permanent magnet electric drive system attached to the crankshaft, variable angular velocities of the engine crankshaft were implemented. The system enabled reductions in piston velocity around the top dead centre region to a fraction of its value at constant crankshaft angular velocity typical in conventional engines. A quasi-constant volume combustion has thus been successfully achieved, leading to improvements in engine fuel consumption and power output which are discussed in detail