An aircraft Earth station for general aviation

While the focus has been international commercial air traffic, an opportunity exists to provide satellite communications to smaller aircraft. For these users equipment cost and weight critically impact the decision to install satellite communications equipment. Less apparent to the operator is the need for a system infrastructure that will be supported both regionally and internationally and that is compatible with the ground segment being installed for commercial aeronautical satellite communications. A system concept is described as well as a low cost terminal that are intended to satisfy the small aircraft market

Modelling manufacturing planning and control systems:the application of object-oriented principles and discrete-event simulation

Manufacturing planning and control systems are fundamental to the successful operations of a manufacturing organisation. 10 order to improve their business performance, significant investment is made by companies into planning and control systems; however, not all companies realise the benefits sought Many companies continue to suffer from high levels of inventory, shortages, obsolete parts, poor resource utilisation and poor delivery performance. This thesis argues that the fit between the planning and control system and the manufacturing organisation is a crucial element of success. The design of appropriate control systems is, therefore, important. The different approaches to the design of manufacturing planning and control systems are investigated. It is concluded that there is no provision within these design methodologies to properly assess the impact of a proposed design on the manufacturing facility. Consequently, an understanding of how a new (or modified) planning and control system will perform in the context of the complete manufacturing system is unlikely to be gained until after the system has been implemented and is running. There are many modelling techniques available, however discrete-event simulation is unique in its ability to model the complex dynamics inherent in manufacturing systems, of which the planning and control system is an integral component. The existing application of simulation to manufacturing control system issues is limited: although operational issues are addressed, application to the more fundamental design of control systems is rarely, if at all, considered. The lack of a suitable simulation-based modelling tool does not help matters. The requirements of a simulation tool capable of modelling a host of different planning and control systems is presented. It is argued that only through the application of object-oriented principles can these extensive requirements be achieved. This thesis reports on the development of an extensible class library called WBS/Control, which is based on object-oriented principles and discrete-event simulation. The functionality, both current and future, offered by WBS/Control means that different planning and control systems can be modelled: not only the more standard implementations but also hybrid systems and new designs. The flexibility implicit in the development of WBS/Control supports its application to design and operational issues. WBS/Control wholly integrates with an existing manufacturing simulator to provide a more complete modelling environment

Biotic interactions in soil and dung shape parasite transmission in temperate ruminant systems : An integrative framework

ACKNOWLEDGMENTS We are thankful to QUADRAT doctoral training partnership for providing the opportunity to complete this work. This work was supported by a QUADRAT doctoral training program PhD studentship from UK Research and Innovation, via the Natural Environment Research Council. Natural Environment Research Council (NERC). Grant Number: NE/S007377/1 UKRIPeer reviewe

Power tool use in orthopaedic surgery: iatrogenic injury, its detection and technological advances

Background: Power tools are an integral part to orthopaedic surgery but have the capacity to cause iatrogenic injury. This systematic review aimed to investigate the prevalence of iatrogenic injury due to power tools in orthopaedic surgery and discuss the current methods 9that can be used to reduce this. Methods: A systematic review of all English language articles using a keyword search was undertaken in Medline, Embase, PubMed and Scopus databases. Exclusion criteria included injuries related to cast saw, temperature induced damage and complications not clearly related to power tool use. Results: 3694 abstracts were retrieved, and 88studies were included in the final analysis. Only a few studies and individual case reports directly looked at prevalence of injury due to power tools. This included 2 studies looking at frequency of vascular injury during femoral fracture fixation (0.49% and 0.2%),2 studies investigating frequency of vertebral artery injury during spinal surgery (0.5% and 0.08%)and 3 studies investigating vascular injury during total joint arthroplasty (124 vascular injuries involving 138 blood vessels,0.13% and 0.1% incidence)in addition to 1 questionnaire sent electronically to surgeons. There are multiple methods to prevent damage during the use of power tools. These include robotics, Revised Manuscript (Maximum 3000 Words) simulation, specific drill settings and real-time feedback techniques such as spectroscopy and electromyography. Conclusion: Power tools have the potential to cause iatrogenic injury to surrounding structures during orthopaedic surgery. Fortunately, the published literature suggests the frequency of iatrogenic injury using orthopaedic power tools is low. There are multiple technologies available to reduce damage using power tools. In high-risk operations the use of advanced technologies to reduce the chance of iatrogenic injury should be considered. Clinical Relevance: Power tools used during orthopaedic surgery have the potential to cause iatrogenic injury through mechanisms such as plunging or over-sawing. Understanding the prevalence of these injuries and mechanisms to increase safety would be useful to surgeons in their daily practice and have the potential to reduce iatrogenic injury in future

An in vitro model of impaction during hip arthroplasty

Impaction is required to properly seat press-fit implants and ensure initial implant stability and long term bone ingrowth, however excessive impaction or press-fit presents a high fracture risk in the acetabulum and femur. Current in-vitro impaction testing methods do not replicate the compliance of the soft tissues surrounding the hip, a factor that may be important in fracture and force prediction. This study presents the measurement of compliance of the soft tissues supporting the hip during impaction in operative conditions, and replicates these in vitro. Hip replacements were carried out on 4 full body cadavers while impact force traces and acetabular/femoral displacement were measured. Compliance was then simulated computationally using a Voigt model. These data were subsequently used to inform the design of a representative in-vitro drop rig. Effective masses of 19.7 kg and 12.7 kg, spring stiffnesses of 8.0 kN/m and 4.1 kN/m and dashpot coefficients of 595 N s/m and 322 N s/m were calculated for the acetabular and femoral soft tissues respectively. A good agreement between cadaveric and in-vitro peak displacement and rise time during impact is found. Such an in-vitro setup is of use during laboratory testing, simulation or even surgical training

Root-TRAPR: a modular plant growth device to visualize root development and monitor growth parameters, as applied to an elicitor response of Cannabis sativa

Background Plant growth devices, for example, rhizoponics, rhizoboxes, and ecosystem fabrication (EcoFAB), have been developed to facilitate studies of plant root morphology and plant-microbe interactions in controlled laboratory settings. However, several of these designs are suitable only for studying small model plants such as Arabidopsis thaliana and Brachypodium distachyon and therefore require modification to be extended to larger plant species like crop plants. In addition, specific tools and technical skills needed for fabricating these devices may not be available to researchers. Hence, this study aimed to establish an alternative protocol to generate a larger, modular and reusable plant growth device based on different available resources. Results Root-TRAPR (Root-Transparent, Reusable, Affordable three-dimensional Printed Rhizo-hydroponic) system was successfully developed. It consists of two main parts, an internal root growth chamber and an external structural frame. The internal root growth chamber comprises a polydimethylsiloxane (PDMS) gasket, microscope slide and acrylic sheet, while the external frame is printed from a three-dimensional (3D) printer and secured with nylon screws. To test the efficiency and applicability of the system, industrial hemp (Cannabis sativa) was grown with or without exposure to chitosan, a well-known plant elicitor used for stimulating plant defense. Plant root morphology was detected in the system, and plant tissues were easily collected and processed to examine plant biological responses. Upon chitosan treatment, chitinase and peroxidase activities increased in root tissues (1.7- and 2.3-fold, respectively) and exudates (7.2- and 21.6-fold, respectively). In addition, root to shoot ratio of phytohormone contents were increased in response to chitosan. Within 2 weeks of observation, hemp plants exhibited dwarf growth in the Root-TRAPR system, easing plant handling and allowing increased replication under limited growing space. Conclusion The Root-TRAPR system facilitates the exploration of root morphology and root exudate of C. sativa under controlled conditions and at a smaller scale. The device is easy to fabricate and applicable for investigating plant responses toward elicitor challenge. In addition, this fabrication protocol is adaptable to study other plants and can be applied to investigate plant physiology in different biological contexts, such as plant responses against biotic and abiotic stresses

The design and in vivo testing of a locally stiffness-matched porous scaffold

An increasing volume of work supports utilising the mechanobiology of bone for bone ingrowth into a porous scaffold. However, typically during in vivo testing of implants, the mechanical properties of the bone being replaced are not quantified. Consequently there remains inconsistencies in the literature regarding ‘optimum’ pore size and porosity for bone ingrowth. It is also difficult to compare ingrowth results between studies and to translate in vivo animal testing to human subjects without understanding the mechanical environment. This study presents a clinically applicable approach to determining local bone mechanical properties and design of a scaffold with similar properties. The performance of the scaffold was investigated in vivo in an ovine model. The density, modulus and strength of trabecular bone from the medial femoral condyle from ovine bones was characterised and power-law relationships were established. A porous titanium scaffold, intended to maintain bone mechanical homeostasis, was additively manufactured and implanted into the medial femoral condyle of 6 ewes. The stiffness of the scaffold varied throughout the heterogeneous structure and matched the stiffness variation of bone at the surgical site. Bone ingrowth into the scaffold was 10.73 ± 2.97% after 6 weeks. Fine woven bone, in the interior of the scaffold, and intense formations of more developed woven bone overlaid with lamellar bone at the implant periphery were observed. The workflow presented will allow future in vivo testing to test specific bone strains on bone ingrowth in response to a scaffold and allow for better translation from in vivo testing to commercial implants

Thermal properties of cubic KTa 1 x Nb x O 3 crystals

Cubic potassium tantalite niobate KTa1−xNbxO3 KTN crystals of large size, good quality, and varying Nb concentration have been grown by the Czochralski method and their thermal properties have been systematically studied. The melting point, molar enthalpy of fusion, and molar entropy of fusion of the crystals were determined to be: 1536.9 K, 12 068.521 J mol−1, and 7.85 J K−1 mol−1 for KTa0.67Nb0.33O3; and 1520.61 K, 15 352.511 J mol−1, and 10.098 J K−1 mol−1 for KTa0.67Nb0.33O3, respectively. Based on the data, the Jackson factor was calculated to be 0.994f and 1.214f for KTa0.67Nb0.33O3 and KTa0.63Nb0.37O3, respectively. The thermal expansion coefficients over the temperature range of 298.15−773.15 K are: =4.0268 10−6 /K, 6.4428 10−6 /K, 6.5853 10−6 /K for KTaO3, KTa0.67Nb0.33O3, and KTa0.63Nb0.37O3, respectively. The density follows an almost linear decrease when the temperature increases=from 298.15 to 773.15 K. The measured specific heats at 303.15 K are: 0.375 J g−1 K−1 for KTaO3; 0.421 J g−1 K−1 for KTa0.67Nb0.33O3, and 0.430 J g−1 K−1 for KTa0.63Nb0.37O3 The thermal diffusion coefficients of the crystals were measured over the temperature range from 303.15−563.15 K. The calculated thermal conductivity values of KTaO3, KTa0.67Nb0.33O3, and KTa0.63Nb0.37O3 at 303.15 K are 8.551, 5.592, and 4.489 W m−1 K−1, respectively. The variation of these thermal properties versus Nb concentration is qualitatively analyzed. These results show that crystalline KTN is a promising material for optical applications