2,287 research outputs found
Carbon Brainprint Case Study: optimising defouling schedules for oil- refinerypreheat trains
In an oil refinery, crude oil is heated to 360-370°C before entering a
distillation columnoperating at atmospheric pressure where the gas fraction and
several liquid fractions withdifferent boiling points (e.g. gasoline, kerosene,
diesel, gas oil, heavy gas oil) are separated off.The crude oil is heated in two
stages. The preheat train - a series of heat exchangers - heats itfrom ambient
temperature to about 270°C when it enters the furnace, known as the coil
inlettemperature. The furnace then heats the oil to the temperature required for
distillation.The purpose of the preheat train is to recover heat from the liquid
products extracted in thedistillation column. Without this, 2-3% of the crude
oil throughput would be used for heating thefurnace; with the preheat train up
to 70% of the required heat is recovered. It also serves tocool the refined
products: further cooling normally uses air or water.
Over time, fouling reduces the performance of the heat exchangers, increasing
the amount ofenergy that has to be supplied. It is possible to bypass units to
allow them to be cleaned, withan associated cost and temporary loss of
performance. The cleaning schedule thus has animpact on the overall efficiency,
cost of operation and emissions.
The group at the Department of Chemical Engineering and Biotechnology at
Cambridgedeveloped a scheduling algorithm for this non-linear optimisation
problem. It yields a good,though not-necessarily optimal, schedule and can
handle additional constraints, such as thepresence of desalters with specific
temperature requirements within the preheat train. This isnow being developed
into a commercial software product.
Data from two refineries - one operated by Repsol YPF in Argentina and the Esso
FawleyRefinery in the UK - were used to model the systems and test the
algorithm.
For the Repsol YPF refinery, when compared with current practice and including a
constrainton the desalter inlet temperature, the most conservative estimate of
the emissions reductionwas 773 t CO2/year. This assumed a furnace efficiency of
90%. The emissions reductionincreased to 927 t CO2/year at 75% efficiency and
1730 t CO2/year at 40%. These were basedon a stoichiometric estimate of the
emissions from the furnace. Using a standard emissionfactor increased them by
7.4%.
For Esso Fawley, the estimated emission reduction compared to no maintenance
was1435 t CO2/year at 90% furnace efficiency. This increased to 1725 t CO2/year
at 75% and3225 t CO2/year at 40% efficien
Covenant Marriage Turns Five Years Old
Part I of this article discusses public policy rationales behind covenant marriage legislation, describes relevant aspects of Louisiana\u27s legislation, and summarizes the efforts of other states to enact covenant marriage legislation. Part II discusses methods of data collection and analysis and identifies the demographic characteristics of covenant married couples as opposed to standard married couples in Louisiana. Part III addresses the dynamics behind couples\u27 choice to have a covenant versus standard marriage. Part IV is an analysis of couples\u27 satisfaction with their marriage option and the gendered dynamics of different levels of satisfaction with the marital choice
Covenant Marriage Turns Five Years Old
Part I of this article discusses public policy rationales behind covenant marriage legislation, describes relevant aspects of Louisiana\u27s legislation, and summarizes the efforts of other states to enact covenant marriage legislation. Part II discusses methods of data collection and analysis and identifies the demographic characteristics of covenant married couples as opposed to standard married couples in Louisiana. Part III addresses the dynamics behind couples\u27 choice to have a covenant versus standard marriage. Part IV is an analysis of couples\u27 satisfaction with their marriage option and the gendered dynamics of different levels of satisfaction with the marital choice
Nurses\u27 Alumnae Association Bulletin, April 1959
Alumnae News
Anniversary Class of /34
Article from Pennsylvania Nurse
Committee Reports
Current Events at Jefferson
Greetings from the President
Jefferson Story
Lost Members
Letter - Past President
Marriages
Necrology
New Arrivals
Notices
Pictured - Student Nurses\u27 Residence
Report of the School of Nursing and Nursing Services
Staff Nurses Social Functions
Student Activities
Voluntary Service
Year of Great Activity and Expansio
Magnetoentropic mapping and computational modeling of cycloids and skyrmions in the lacunar spinels GaVS and GaVSe
We report the feasibility of using magnetoentropic mapping for the rapid
identification of magnetic cycloid and skyrmion phases in uniaxial systems,
based on the GaV4S8 and GaV4Se8 model skyrmion hosts with easy-axis and
easy-plane anisotropies respectively. We show that these measurements can be
interpreted with the help of a simple numerical model for the spin Hamiltonian
to yield unambiguous assignments for both single phase regions and phase
boundaries. In the two lacunar spinel chemistries, we obtain excellent
agreement between the measured magnetoentropic features and a minimal spin
Hamiltonian built on Heisenberg exchange, single-ion anisotropy, and
anisotropic Dzyaloshinskii-Moriya interactions. In particular, we identify
characteristic high-entropy behavior in the cycloid phase that serves as a
precursor to the formation of skyrmions at elevated temperatures and is a
readily-measurable signature of this phase transition. Our results demonstrate
that rapid magnetoentropic mapping guided by numerical modeling is an effective
means of understanding the complex magnetic phase diagrams innate to skyrmion
hosts. One notable exception is the observation of an anomalous,
low-temperature high-entropy state in the easy-plane system GaVSe,
which is not captured in the numerical model. Possible origins of this state
are discussed.Comment: 10 pages and 7 figure
External and internal grouping characteristics of juvenile walleye pollock in the Eastern Bering Sea
Size and shape patterns of fish groups are collective outcomes of interactions among members. Consequently, group-level patterns are often affected when any member responds to changes in their internal state, external state, and environment. To determine how groups of fish respond to components of their physical and ecological environment, and whether the response is influenced by a component of their external state (i.e., fish age), we used a multibeam system to collect three-dimensional grouping characteristics of 5 age categories of juvenile walleye pollock (age 1, age 2, age 3, mixed ages 1 and 2, and mixed ages 2 and 3) across the eastern Bering Sea shelf over two consecutive years (2009–2010). Grouping data were expressed as metrics that described group size (length, height), shape (roundness, spread), internal structure (density, internal heterogeneity), and position (depth, distance above bottom). Physical data (water temperature measurements) were collected with temperature-depth probes, and ecological data (densities of predators and prey − adult walleye pollock and euphausiids, respectively) were collected with an EK60 vertical echosounder. Juvenile pollock maintained a relatively constant shape, size-dependent density (number fish/mean body length3), and internal horizontal heterogeneity among age categories and in the presence of predators and prey. There were changes to group structure in the face of local physical forcing. Groups tended to move towards the seafloor when bottom waters became warmer, and groups became vertically shorter, denser, and had more variation in horizontal internal density as group depth increased. These results are explored in relation to the value and limitations of using multibeam data to describe how external and internal group structure map onto environmental influences
Nurses\u27 Alumnae Association Bulletin, June 1964
President\u27s Message
Officers and Committee Chairmen
Financial Report
Hospital and School of Nursing Report
Student Activities
Jefferson Expansion Program
Resume of Alumnae Meetings
Staff Nurses
Private Duty
Social Committee Reports
Program
Scholarship
Bulletin Committee Report
Annual Luncheon Notes
Membership and Dues
Units in Jefferson Expansion Program Center
Annual Giving Drive 1963
Report of Ways and Means Committee
Jefferson Building Fund Contributions
Annual Giving Contributions 1964
Jefferson Building Fund Report
Help the Building Fund Committee!
Vital Statistics
Class News
Notice
Herschel SPIRE-FTS Observations of Excited CO and [CI] in the Antennae (NGC 4038/39): Warm and Cold Molecular Gas
We present Herschel SPIRE-FTS observations of the Antennae (NGC 4038/39), a
well studied, nearby ( Mpc) ongoing merger between two gas rich spiral
galaxies. We detect 5 CO transitions ( to ), both [CI]
transitions and the [NII] transition across the entire system, which
we supplement with ground based observations of the CO , and
transitions, and Herschel PACS observations of [CII] and [OI].
Using the CO and [CI] transitions, we perform both a LTE analysis of [CI], and
a non-LTE radiative transfer analysis of CO and [CI] using the radiative
transfer code RADEX along with a Bayesian likelihood analysis. We find that
there are two components to the molecular gas: a cold ( K)
and a warm ( K) component. By comparing the warm gas mass
to previously observed values, we determine a CO abundance in the warm gas of
. If the CO abundance is the same in the warm and
cold gas phases, this abundance corresponds to a CO luminosity-to-mass
conversion factor of $\alpha_{CO} \sim 7 \ M_{\odot}{pc^{-2} \ (K \ km \
s^{-1})^{-1}}_263\mu m\sim 0.01 L_{\odot}/M_{\odot}G_0\sim 1000$. Finally, we find
that a combination of turbulent heating, due to the ongoing merger, and
supernova and stellar winds are sufficient to heat the molecular gas.Comment: 50 pages, 15 figures, 8 tables, Accepted for publication in The
Astrophysical Journa
Nurses\u27 Alumnae Association Bulletin, June 1965
President\u27s Page
Officers and Committee Chairmen
Financial Report
Hospital and School of Nursing Report
Student Activities Annual Report
Students Activities Annual Report
Student Activities Annual Report
Jefferson Expansion Program
Psychiatric Unit
Progress of the Alumnae Association
Nightingale Pledge
Resume of Alumnae Meetings
Nursing Service Staff Association
Scholarship
Program
Sick and Welfare
Social Committee Report
Bulletin
Membership- WHY JOIN?
Private Duty Report
Annual Giving Report - 1964
PIT
Alumnae Day Notes
Building Fund Report - 1965
Vital Statistics
IN MEMORIAM
Class News
Affiliated Institutions
Notice
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