Mesoscale Calculations of the Dynamic Behavior of a Granular Ceramic

Mesoscale calculations have been conducted in order to gain further insight into the dynamic compaction characteristics of granular ceramics. The primary goals of this work are to numerically determine the shock response of granular tungsten carbide and to assess the feasibility of using these results to construct the bulk material Hugoniot. Secondary goals include describing the averaged compaction wave behavior as well as characterizing wave front behavior such as the strain rate versus stress relationship and statistically describing the laterally induced velocity distribution. The mesoscale calculations were able to accurately reproduce the experimentally determined Hugoniot slope but under predicted the zero pressure shock speed by 12%. The averaged compaction wave demonstrated an initial transient stress followed by asymptotic behavior as a function of grain bed distance. The wave front dynamics demonstrate non-Gaussian compaction dynamics in the lateral velocity distribution and a power-law strain rate–stress relationship

An annotated catalogue of the Lepidoptera collection of Guido Lanfranco at the National Museum of Natural History in Malta

An annotated list of the lepidoptera in the Lanfranco collection donated to the National Museum of Natural History of Mdina in Malta is included. Where relevant, comments on particular species or specimens are provided.peer-reviewe

Piggybacking on an Autonomous Hauler: Business Models Enabling a System-of-Systems Approach to Mapping an Underground Mine

With ever-increasing productivity targets in mining operations, there is a growing interest in mining automation. In future mines, remote-controlled and autonomous haulers will operate underground guided by LiDAR sensors. We envision reusing LiDAR measurements to maintain accurate mine maps that would contribute to both safety and productivity. Extrapolating from a pilot project on reliable wireless communication in Boliden's Kankberg mine, we propose establishing a system-of-systems (SoS) with LIDAR-equipped haulers and existing mapping solutions as constituent systems. SoS requirements engineering inevitably adds a political layer, as independent actors are stakeholders both on the system and SoS levels. We present four SoS scenarios representing different business models, discussing how development and operations could be distributed among Boliden and external stakeholders, e.g., the vehicle suppliers, the hauling company, and the developers of the mapping software. Based on eight key variation points, we compare the four scenarios from both technical and business perspectives. Finally, we validate our findings in a seminar with participants from the relevant stakeholders. We conclude that to determine which scenario is the most promising for Boliden, trade-offs regarding control, costs, risks, and innovation must be carefully evaluated.Comment: Preprint of industry track paper accepted for the 25th IEEE International Conference on Requirements Engineering (RE'17

Sand Penetration: A Near Nose Investigation of a Sand Penetration Event

This paper presents experimental and computational results of a long-rod penetrating dry granular sand at velocities near 100 m/s. The objective of this work is to develop a fundamental understanding of the formation and transmission of dynamic force chains, and the motion and fracture of the individual sand grains as the projectile passes. This is accomplished by launching a projectile along a view window, backed by sand, in order to directly view and photograph the projectile/sand interactions. Within the sand system, a two-wave structure was observed, composed of a compaction wave (bow shock) that detaches from the dart and moves through the sand at a wave speed near 100 m/s and a damage wave, which remains near the leading edge of the dart. The compaction wave removes porosity and the damage wave fractures grains in the region near the projectile nose. Grain fracture is not observed at dart speeds below 35 m/s. In addition the axial strain to failure of individual sand grains was measured in a quasi-static configuration. These results were used in conjunction with a simple analytic force balance model to predict the depth of penetration. The analytic results compare favourably with experiments until the dart slows below 35 m/s

First record of Xenopsylla gratiosa Jordan & Rothschild, 1923 from the Maltese Islands (Siphonaptera: Pulicidae)

Xenopsylla gratiosa is reported for the first time from the Maltese Islands. The species was found in an abandoned nest of a Cory’s Shearwater, Calonectris diomedea on the island of Filfla. Brief notes are included on previous records of fleas from the Maltese Islands and taxonomic, distributional and ecological notes are provided for Xenopsylla gratiosapeer-reviewe

Preliminary notes on the early stages of Isturgia pulinda (Walker, 1860) (Lepidoptera: Geometridae)

The early stages, larval hostplant and voltism of Isturgia pulinda in the Maltese Islands are documentedpeer-reviewe

Equation of State and Isentropic Releasem of Aluminum Foam and Fluoropolymer Composites

There is considerable interest in developing a better understanding of the dynamic behavior of heterogeneous materials. This study investigates and compares the dynamic response of 20 and 47% dense aluminum foam systems with and without a polytetrafluoroethylene (PTFE or Teflon) fill. Experiments on 47% foam were conduced in a 60 mm bore gun in a reverse ballistic configuration at velocities ranging from 350 m/s to 2.5 km/s. The particle velocity of the backside of the anvil was monitored with a VISAR system. Mesoscale simulations are in good agreement with the available experimental data. Both the experimental and simulated data are in good agreement with an analytic release isentrope when released from Hugoniot stress levels less than 5 GPa. However there is significant deviation from the analytic isentrope as the Hugoniot stress level is increased

Concordance with the British Society of Rheumatology (BSR) 2010 recommendations on eligibility criteria for the first biologic agent

Aims: The aim of this study is to assess concordance with the British Society of Rheumatology (BSR) 2010 recommendations on the use of biologic therapy in Rheumatoid Arthritis (RA). The Disease Activity Score in 28 joints (DAS 28), a composite numerical score is included in these recommendations to assess disease activity and response to treatment. Methods: Clinical notes of fifty patients who were commenced on biologic treatment between March 2010 and June 2011 were reviewed for documentation of DAS 28 scores at baseline, after approximately 6 months of commencement of treatment and at approximately 6 monthly intervals during treatment. Results: Twenty two patients were eligible for this audit. Of these patients only half had a DAS 28 score performed prior to starting treatment, four patients had the score performed within 3-9 months of commencement of therapy and only 2 patients had continuous scores performed at six monthly intervals during treatment. Conclusions: This audit shows that we are not adhering to the BSR recommendations. In order to improve our adherence we plan to train all staff in contact with patients on biologic treatment to perform DAS 28 scores and have a DAS 28 calculator readily available at out patients. A proforma is being developed for patients on biologic therapy to ensure that DAS 28 scores are performed at baseline and during treatment.peer-reviewe

A checklist to the quaternary avifauna of the Maltese islands preliminary note

The Maltese Quaternary fauna is more or less well documented, with most works concentrating mainly on the pachyderms, ungulates and micro-mammals. Less known is the variable amount of avian remains unearthed from various sites. The only avian species which has to some extent been studied in detail are Cygnus falconeri and Grus melitensis. The other 44 species or genera which have been discovered and identified are less documented. Of these, no less than six species were endemic to Malta and/or the Mediterranean region. The Maltese Quaternary avifauna has been previously documented by Parker (1865, 1869), Adams (1866, 1867, 1870), Spratt (1867), Lydekker (1890, 1891), Bate (1916), Caton Thompson (1923), Despott (1924-25, 1926- 27, 1928-29), Fischer & Stephan (1974), Northcote (1982a, 1982b, 1981-83, 1984, 1984-85, 1988) and Weesie (1987).peer-reviewe

Mostly Tuesday Series:Guest Artist:John E. Borg, Viola Faculty Artist:Paul W. Borg, Piano

Center for the Performing Arts Tuesday Evening October 22, 2002 8:00p.m