4,698 research outputs found
Sintered aluminium heat pipe (SAHP)
This work is the product of an ongoing PhD project in the School of the Built and Natural Environment of Northumbria University in collaboration with the University of Liverpool and Thermacore Europe Ltd. The achievements at the end of the first year are summarized. The main objective of the project is to develop an aluminum ammonia heat pipe with a sintered wick structure. Currently available ammonia heat pipes mainly use extruded axially grooved aluminum tubes as a capillary wick. There have been a few attempts of employing porous steel or nickel wicks in steel tubes with ammonia as the working fluid (Bai, Lin et al. 2009)although it is a common practice in loop heat pipes but there is no report of aluminum-ammonia heat pipes porous aluminium wick structures. The main barrier is the difficulty of sintering aluminum powders to manufacture porous wicks. So far during this project promising sintered aluminum heat pipe samples have been manufactured using the Selective Laser Melting (SLM) technique with various wick characteristics. This SLM method has proven to be capable of manufacturing very complicated wick structures with different thickness, porosity, permeability and pore sizes in different regions of a heat pipe. In addition the entire heat pipe including the end cap, outer tube wall, wick and the fill tube can be generated in a single process
A Philosophical Look into the Morality and Legality of Abortion
In his Nicomachean Ethics, Greek philosopher Aristotle posits an understanding of ethics and how human life is characterized by the “good.” Aristotle argues that (I) ethics involve humans possessing a rational capacity and specific function; (II) ethics are habitual, and the “doctrine of the mean” is used to gauge proper action; and (III) justice is linked to virtue. A moral issue that can be analyzed through Aristotle’s Ethics, as well as works of contemporary philosophers, is abortion. Abortion has been a controversial topic and has been brought before the Supreme Court to determine its morality and legality. Using Aristotle’s Ethics as a foundation, as well as drawing from the works of contemporary philosophers, this thesis will explore hypothetical examples to examine how morality and legality apply to abortion, in that it can be moral but not legal; legal but not moral; both moral and legal; and neither moral nor legal
Image reconstruction from photon sparse data
We report an algorithm for reconstructing images when the average number of photons recorded per pixel is of order unity, i.e. photon-sparse data. The image optimisation algorithm minimises a cost function incorporating both a Poissonian log-likelihood term based on the deviation of the reconstructed image from the measured data and a regularization-term based upon the sum of the moduli of the second spatial derivatives of the reconstructed image pixel intensities. The balance between these two terms is set by a bootstrapping technique where the target value of the log-likelihood term is deduced from a smoothed version of the original data. When compared to the original data, the processed images exhibit lower residuals with respect to the true object. We use photon-sparse data from two different experimental systems, one system based on a single-photon, avalanche photo-diode array and the other system on a time-gated, intensified camera. However, this same processing technique could most likely be applied to any low photon-number image irrespective of how the data is collected
Methods for the evaluation of alternative disaster warning systems
For each of the methods identified, a theoretical basis is provided and an illustrative example is described. The example includes sufficient realism and detail to enable an analyst to conduct an evaluation of other systems. The methods discussed in the study include equal capability cost analysis, consumers' surplus, and statistical decision theory
Methods for the evaluation of alternative disaster warning systems. Executive summary
Methods for estimating the economic costs and benefits of the transmission-reception and reception-action segments of a disaster warning system (DWS) are described. Methods were identified for the evaluation of the transmission and reception portions of alternative disaster warning systems. Example analyses using the methods identified were performed
Discriminating single-photon states unambiguously in high dimensions
The ability to uniquely identify a quantum state is integral to quantum
science, but for non-orthogonal states, quantum mechanics precludes
deterministic, error-free discrimination. However, using the non-deterministic
protocol of unambiguous state discrimination (USD) enables error-free
differentiation of states, at the cost of a lower frequency of success. We
discriminate experimentally between non-orthogonal, high-dimensional states
encoded in single photons; our results range from dimension to . We
quantify the performance of our method by comparing the total measured error
rate to the theoretical rate predicted by minimum-error state discrimination.
For the chosen states, we find a lower error rate by more than one standard
deviation for dimensions up to . This method will find immediate
application in high-dimensional implementations of quantum information
protocols, such as quantum cryptography.Comment: 4 pages + 3 pages supplementary, 4 figure
Plane Decompositions as Tools for Approximation
Tree decompositions were developed by Robertson and Seymour [21]. Since then algorithms have been developed to solve intractable problems efficiently for graphs of bounded tree width. In this paper we extend tree decompositions to allow cycles to exist in the decomposition graph; we call these new decompositions plane decompositions because we require that the decomposition graph be planar. First, we give some background material about tree decompositions and an overview of algorithms both for decompositions and for approximations of planar graphs. Then, we give our plane decomposition definition and an algorithm that uses this decomposition to approximate the size of the maximum independent set of the underlying graph in polynomial time
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