Constructing informative Bayesian map priors: A multi-objective optimisation approach applied to indoor occupancy grid mapping

The problem of simultaneous localisation and mapping (SLAM) has been addressed in numerous ways with different approaches aiming to produce faster, more robust solutions that yield consistent maps. This focus, however, has resulted in a number of solutions that perform poorly in challenging real life scenarios. In order to achieve improved performance and map quality this article proposes a novel method to construct informative Bayesian mapping priors through a multi-objective optimisation of prior map design variables defined using a source of prior information. This concept is explored for 2D occupancy grid SLAM, constructing such priors by extracting structural information from architectural drawings and identifying optimised prior values to assign to detected walls and empty space. Using the proposed method a contextual optimised prior can be constructed. This prior is found to yield better quantitative and qualitative performance than the commonly used non-informative prior, yielding an increase of over 20% in the F2 metric. This is achieved without adding to the computational complexity of the SLAM algorithm, making it a good fit for time critical real life applications such as search and rescue missions

Necessary and sufficient conditions for two variable orthogonal designs in order 44: Addendum

In our recent paper Necessary and sufficient conditions for some two variable orthogonal designs in order 44, Koukouvinos, Mitrouli and Seberry leave 7 cases unresolved. Using a new algorithm given in our paper A new algorithm for computer searches for orthogonal designs by the present four authors we are able to finally resolve all these cases. This note records that the necessary conditions for the existence of two variable designs constructed using four circulant matrices are sufficient. In particular of 484 potential cases 404 cases have been found, 68 cases do not exist and 12 cases cannot be constructed using four circulant matrices

Localized buckling in sandwich struts with inhomogeneous deformation in both face plates

A nonlinear analytical model for investigating localized interactive buckling in simply supported thin-face plate sandwich struts with weak cores is extended to account for local deformations in both face plates, which have been observed in experiments and finite element simulations. The original model is based on potential energy principles with large displacement assumptions. It assumes Timoshenko shear deformable theory for the core and approximates the overall mode as a half-sine wave along the length of the strut while the local face plate displacements are initially unknown and are found as solutions of the governing equations. The extended model is able to capture measurable local face plate displacements in the less compressed face plate, beyond the secondary bifurcation which leads to localized interactive buckling, for the case where overall buckling is critical. Moreover, the allowance of local displacements in both face plates allows the extended model to predict the post-buckling behavior better in cases where local buckling is critical. The results from this model compare very well with nonlinear finite element simulations with respect to both the equilibrium paths and panel deformations

Necessary and Sufficient Conditions for Three and Four Variable Orthogonal Designs in Order 36

We use a new algorithm to find new sets of sequences with entries from {0, ±a, ±b, ±c, ±d}, on the commuting variables a, b, c, d, with zero autocorrelation function. Then we use these sequences to construct a series of new three and four variable orthogonal designs in order 36. We show that the necessary conditions plus (.s1, s2, s3, s4) not equal to 12816 18 816 221313 26721 36 816 4889 12825 191313 23 424 289 9 381015 8899 14425 22 916 are sufficient for the existence of an OD(36; s1, s2 s3, s4) constructed using four circulant matrices in the Goethals-Seidel array. Of the 154 theoretically possible cases 133 are known. We also show that the necessary conditions plus (s1, s2 s3) ≠ (2,8,25), (6,7,21), (8, 9, 17) or (9, 13, 13) are sufficient for the existence of an OD(36; s1, s2, s3) constructed using four circulant matrices in the Goethals-Seidel array. Of the 433 theoretically possible cases 429 are known. Further, we show that the necessary conditions are sufficient for the existence of an OD(36; s1, s2 36 — s1 — s2) in each of the 54 theoretically possible cases. Further, of the 27 theoretically possible OD(36; s1, s2, s3, 36 — s1 — s2 — s3), 23 are known to exist, and four, (1,2,8,25), (1, 9,13,13), (2,6,7,21) and (3, 8,10,15), cannot be constructed using four circulant matrices. By suitably replacing the variables by ±1 these lead to more than 200 potentially inequivalent Hadamard matrices of order 36. By considering the 12 OD(36; 1, s1, 35—s1) and suitably replacing the variables by ±1 we obtain 48 potentially inequivalent skew-Hadamard matrices of order 36. A summary with all known results in order 36 is presented in the Tables

Application of liquid-air and pumped-thermal electricity storage systems in low-carbon electricity systems

In this study, w e consider two medium - to large - scale electricity storage systems currently under development, namely ‘Liquid - Air Energy Storage’ (LAES) and ‘Pumped - Therma l Electricity Storage’ (PTES). Consistent t hermodynamic models and costing methodologies for the two systems are presented , with the object ive of integrating the characteristics of these technologies in to a whole - electricity system assessment model , and assess ing the ir system - level value in different scenarios for power system decarbonisation . It is found that the value of storage varies greatly depending on the cumulative installed ca pacity of storage in the electrical system, with the s torage technologies provid ing greater marginal benefits at low p enetrations . T wo carbon target scenarios showed similar results, with a limited effect of the carbon target on the system value of storage (although it is noted that this may change for even more ambitious carbon targets). On the other hand, the location and installed capacity of storage plants is found to have a significant impact on the syste m value and acceptable cost of the se technologies. The w hole - system value of PTES was found to be slightly higher than that of LAES, driven by a higher storage duration and efficiency, however, due to the higher power capital cost of PTES, this becomes les s attractive for implementat ion at lower volumes than LAES

iMapD: intrinsic Map Dynamics exploration for uncharted effective free energy landscapes

We describe and implement iMapD, a computer-assisted approach for accelerating the exploration of uncharted effective Free Energy Surfaces (FES), and more generally for the extraction of coarse-grained, macroscopic information from atomistic or stochastic (here Molecular Dynamics, MD) simulations. The approach functionally links the MD simulator with nonlinear manifold learning techniques. The added value comes from biasing the simulator towards new, unexplored phase space regions by exploiting the smoothness of the (gradually, as the exploration progresses) revealed intrinsic low-dimensional geometry of the FES

Self-stabilizing virtual synchrony

Virtual synchrony (VS) is an important abstraction that is proven to be extremely useful when implemented over asynchronous, typically large, message-passing distributed systems. Fault tolerant design is critical for the success of such implementations since large distributed systems can be highly available as long as they do not depend on the full operational status of every system participant. Self-stabilizing systems can tolerate transient faults that drive the system to an arbitrary unpredictable configuration. Such systems automatically regain consistency from any such configuration, and then produce the desired system behavior ensuring it for practically infinite number of successive steps, e.g., 264 steps. We present a new multi-purpose self-stabilizing counter algorithm establishing an efficient practically unbounded counter, that can directly yield a self-stabilizing Multiple-Writer Multiple-Reader (MWMR) register emulation. We use our counter algorithm, together with a selfstabilizing group membership and a self-stabilizing multicast service to devise the first practically stabilizing VS algorithm and a self-stabilizing VS-based emulation of state machine replication (SMR). As we base the SMR implementation on VS, rather than consensus, the system progresses in more extreme asynchronous settings in relation to consensusbased SMR

Operator mixing and three-point functions in N=4 SYM

We study the three-point functions between two BPS and one non-BPS local gauge invariant operators in N=4 Super Yang-Mills theory. In particular we show, in explicit 1-loop examples, that the operator mixing discussed in arXiv:0810.0499 plays an important role in the computations of the correlators and is necessary to cancel contributions that would violate the constraints following from the superconformal and the bonus U(1)_Y symmetries. We analyse the same type of correlators also at strong coupling by using the BMN limit of the AdS_5xS^5 string theory. Again the mixing between states with different types of impurities is crucial to ensure the cancellation of various amplitudes that would violate the constraints mentioned above. However, on the string side, we also find some examples of interactions between one non-BPS and two BPS states that do not satisfy expectations based on the superconformal and the bonus U(1)_Y symmetries.Comment: 28 pages, 5 figure

Morphological approach of the sternal foramen: an anatomic study and a short review of the literature

Background: The sternal foramen (SF) constitutes a specific anatomic defect in sternum, indicating an impaired fusion of ossificated segments, which occurs either in an anatomical part of the sternum or in sternal joints. The aim of this article is to provide baseline statistical data about the variations of the SF, to present a short review of the relevant literature and to compare results with other studies and populations. Materials and methods: We review relevant literature, and we present data obtai­ned from skeletal samples of known population and sex. A total of 35 well-preserved dried sterna from the prefecture of Eastern Macedonia and Thrace, Greece, were selected: 20 men and 15 women with a mean age of 55 ± 6 years old. Measurements were made with a sliding calliper and photographic documentation. Results: The incidence of the SF in the 35 dried specimens was 14.2%, 4 men (20% of male sample) and 1 woman (6.6% of female sample) and 80% of sternal foramina were observed in male individuals. The SF was found in the sternum body (2 cases, 40% of foramina), in xiphoid process (2 cases, 40% of foramina) and in sternoxiphoidal junction (1 case, 20% of foramina). All of the sterna presented 1 single visible SF. Two anatomically unique cases were identified throughout these 5 sterna, both belonging in male subjects. Conclusions: The SF constitutes a relatively common variation with great radiological, clinical, and forensic significance. Presence of a SF with irregular bony margins complicates considerably radiological differential diagnosis. Awareness of this important anatomic variation is fundamental for clinicians and autopsy pathologists, in order to avoid severe fatal complications and elucidate the exact cause of death, respectively