22 research outputs found
Approaches to improve mixing in compression ignition engines
This thesis presents three approaches to suppress soot emissions in compression-ignition (CI) engines. First, a fuel chemistry approach is proposed. A particular class of fuels - cyclic oxygenates - is identified which is capable of significantly reducing engine-out soot emissions. By means of experiments in "closed" and optical engines, as well as on an industrial burner, two possible mechanisms are identified that could account for the observed reduction in soot: a) an extended ignition delay (ID) and b) a longer flame lift-off length (FLoL). Further analysis of the available data suggests that both mechanisms are related to the inherently low reactivity of the fuel class in question. These findings are largely in line with data found in literature. In the second approach, it is attempted to reduce soot by adopting an alternative combustion concept: early direct injection premixed charge compression ignition (EDI PCCI). In this concept, fuel is injected relatively early in the compression stroke instead of conventional, close to top-dead-center (TDC), injection schemes. While the goal of soot reduction can indeed be achieved via this approach, an important draw-back must be addressed before this concept can be considered practically viable. Due to the fact that combustion chamber temperature and pressure is relatively low early in the compression stroke, fuel impingement against the cylinder liner (wall-wetting) often occurs. Consequently, high levels of unburned hydrocarbons (UHC), oil dilution and poor efficiency are observed. Several strategies, combining a limited engine modification with dedicated air management and fueling settings, are investigated to tackle this drawback. All of these strategies, and especially their combination, resulted in significantly lower UHC emissions and improved fuel economy. Although UHC emissions are typically a tell-tale sign of wall-wetting, as mentioned earlier, the relation between these two has long been hypothetical. Therefore, computational fluid dynamics (CFD) calculations of the injection process are performed to confirm whether or not liquid fuel impingement on the combustion chamber walls is indeed reduced as a result of the aforementioned UHC reduction strategies. Combined model and experimental results indicate that, for most strategies, the measured hydrocarbon emissions and predicted spray impingement are well correlated for a conventional DI injector nozzle, supporting the earlier assumption that wall-wetting is responsible for high hydrocarbon emissions in the investigated early injection timing approach. Lastly, in the third approach, a new injector nozzle design is proposed to improve the mixing process; again with the aim of soot abatement. In conventional nozzles, fuel is injected through 5-10 holes with nominal diameters of 100-200 micrometer. From both literature and in-house experiments it is known that mixing can be improved by reducing the nozzle diameter. Unfortunately, in order to preserve the overall flow rate, the number of required holes quadratically increases with a reduction in hole diameter. Alternatively, it is proposed to not drill the holes, but to use a porous medium instead. The utilized medium is a sintered metal permeated by an interconnected network of (continuous) pores with nominal diameters of 10 micrometer. This material is machined into a nozzle like shape and subjected to atmospheric injection tests as well as to experiments in the Eindhoven High Pressure Cell. Macroscopic experimental data (e.g. shorter ignition delay, larger spray volume) suggests that mixing is indeed improved. However, more research is required, preferably in a(n) (optical) engine, to investigate the impact on (soot) emissions and overall engine performance. In addition, the issues of durability and fouling still have to be addressed
Super-resolution spatial, temporal and functional characterisation of voltage-gated calcium channels involved in exocytosis
The
process
of
information
transfer
between
neurons
or
endocrine
cells
is
one
of
the
most
important,
intricate
and
temporally
precise
processes
in
the
body.
Exocytosis,
which
is
central
to
the
process
of
excitation-‐secretion
coupling,
is
triggered
by
calcium
signalling
through
voltage-‐gated
calcium
channels.
Super-‐resolution
imaging
offers
the
possibility
to
fully
understand
the
spatial
relationship
between
the
SNARE
proteins
involved
in
exocytosis,
vesicles
and
the
associated
voltage-‐gated
calcium
channels.
In
this
thesis
the
focus
is
on
exploring
the
trigger
for
exocytosis,
specifically
the
spatial
and
functional
role
that
voltage-‐gated
calcium
channels
play
in
this
process.
Super-‐
resolution
imaging
techniques
have
been
applied
to
measure
the
interaction
between
Cav2.2
calcium
channels
and
the
syntaxin1a
SNARE
protein,
where
binding
was
found
to
affect
the
overall
channel
distribution.
A
novel
method
of
caged
dye
conjugated
ω-‐
conotoxin
GVIA
binding
was
developed
for
live
cell
single
molecule
imaging
of
Cav2.2
calcium
channels.
An
innovative
approach
to
analyse
channel
functionality
and
the
distribution
of
calcium
events
at
the
plasma
membrane
was
developed
to
create
a
temporal-‐spatial
map
of
calcium
activity
across
the
cell.
These
developments,
combined
with
newly
developed
techniques
in
optical
patching
and
simultaneous
calcium
and
vesicle
imaging
reveal
the
functional
relationship
of
voltage-‐gated
calcium
channel
and
exocytosis
at
unprecedented
spatial
and
temporal
scales
Optical In-Process Measurement Systems
Information is key, which means that measurements are key. For this reason, this book provides unique insight into state-of-the-art research works regarding optical measurement systems. Optical systems are fast and precise, and the ongoing challenge is to enable optical principles for in-process measurements. Presented within this book is a selection of promising optical measurement approaches for real-world applications
Current Air Quality Issues
Air pollution is thus far one of the key environmental issues in urban areas. Comprehensive air quality plans are required to manage air pollution for a particular area. Consequently, air should be continuously sampled, monitored, and modeled to examine different action plans. Reviews and research papers describe air pollution in five main contexts: Monitoring, Modeling, Risk Assessment, Health, and Indoor Air Pollution. The book is recommended to experts interested in health and air pollution issues
Proceedings of the European Conference on Agricultural Engineering AgEng2021
This proceedings book results from the AgEng2021 Agricultural Engineering Conference under auspices of the European Society of Agricultural Engineers, held in an online format based on the University of Évora,
Portugal, from 4 to 8 July 2021.
This book contains the full papers of a selection of abstracts that were the base for the oral presentations and posters presented at the conference.
Presentations were distributed in eleven thematic areas: Artificial Intelligence, data processing and
management; Automation, robotics and sensor technology; Circular Economy; Education and Rural development; Energy and bioenergy; Integrated and sustainable Farming systems; New application
technologies and mechanisation; Post-harvest technologies; Smart farming / Precision agriculture; Soil, land and water engineering; Sustainable production in Farm buildings
Image Color Correction, Enhancement, and Editing
This thesis presents methods and approaches to image color correction, color enhancement, and color editing. To begin, we study the color correction problem from the standpoint of the camera's image signal processor (ISP). A camera's ISP is hardware that applies a series of in-camera image processing and color manipulation steps, many of which are nonlinear in nature, to render the initial sensor image to its final photo-finished representation saved in the 8-bit standard RGB (sRGB) color space. As white balance (WB) is one of the major procedures applied by the ISP for color correction, this thesis presents two different methods for ISP white balancing. Afterwards, we discuss another scenario of correcting and editing image colors, where we present a set of methods to correct and edit WB settings for images that have been improperly white-balanced by the ISP. Then, we explore another factor that has a significant impact on the quality of camera-rendered colors, in which we outline two different methods to correct exposure errors in camera-rendered images. Lastly, we discuss post-capture auto color editing and manipulation. In particular, we propose auto image recoloring methods to generate different realistic versions of the same camera-rendered image with new colors. Through extensive evaluations, we demonstrate that our methods provide superior solutions compared to existing alternatives targeting color correction, color enhancement, and color editing
Biotechnology
Biotechnological problems of man machine systems required for long duration space flight
Recommended from our members
An exploration of some aspects of molecular replacement in macromolecular crystallography
This thesis reports work in three areas of X-ray crystallography. An initial chapter describes the structure of a protein, the methods based on the use of X-rays and computer analysis of diffraction patterns to determine crystal structure, and the subsequent derivation of the structure of part or all of a protein molecule. Work to determine the structure of the protein cytokine receptor-like factor 3 (CRLF3) leading to the successful generation of a structural model of a significant part of this molecule is then described in Chapter 2. A variety of techniques had to be deployed to complete this work, and the steps undertaken are described. Analysis was performed principally using phaser, using maximum likelihood methods. Areas for improvement in generating non-crystallographic symmetry (NCS) operators in existing programmes were identified and new and modified algorithms implemented and tested. Searches based on improved single sphere algorithms, and a new two-sphere approach, are reported. These methods showed improvements in many cases and are available for future use. In Chapter 4, work on determining the relative importance of low resolution and high intensity data in molecular replacement solutions is described. This work has shown that high intensity data are more important than the low resolution data, dispelling a common perception and helping in experimental design.Welcome Trust funded PhD with a travel fellowship from Instruc
A thin monocrystalline diaphragm pressure sensor using silicon-on-insulator technology.
The sensors market is huge and growing annually, of this a large sector is pressure sensors. With increasing demands on performance there remains a need for ultraminiature,
high performance pressure sensors, particularly for medicai applications.
To address this a novel capacitive pressure sensor consisting of an array of parallel connected diaphragms has been designed and fabricated from SIMOX substrates.
The benefits of this include single crystal silicon diaphragms, small, well controlled dimensions, single sided processing and the opportunity for electronics integration.
Theoretical modelling of this structure predicts a high sensitivity and low stress device with opportunities for scaling to suit alternative applications.
A novel, process technology was developed to achieve the required structure with the inclusion of procedures to address the specific issues relating to the SIMOX material.
The sensor was fully characterised and the results demonstrated high performance compared with similar reported devices. Alternative structures such as cantilevers, bridges and resonators were fabricated as a demonstrative tool to show the feasibility of this technology in a wider field of applications