DSTO Scientific Publications

Scaling of cavity-flow wind-tunnel data

Author: Jones, M.; Watmuff, J.
Issue Date: 10-Aug-2009
Citation: 13th Australian Aeronautical Conference, 9-12 March 2009, Melbourne, Australia

Abstract

This paper examines the issues relevant to the interpretation and scaling of data obtained from wind tunnel experiments on flows over cavities. Data from twelve previously published experiments has been extracted and compared. A characteristic of cavity flows is the aeroacoustic resonance that may occur under certain circumstances. Based on the comparison of the existing data sources, the important parameters affecting the observed resonant frequencies are identified and discussed. To provide a framework for the data analysis existing mathematical and physical models of cavity resonance are reviewed. Finally, some of the experimental issues surrounding measurements of aeroacoustic flows are discussed.

Emergent Naval Technology

Author: Byrne, Duncan
Issue Date: 26-Jul-2009
Citation: Navy Futures Week 2009 at the Australian Command and Staff College Navy Single Service Future's Week, 9th June 2009.

Abstract

Advances in technology will facilitate the development of a number of emerging concepts in the maritime environment that will increasingly be joint in nature. This presentation focuses on technologies and concepts that should be feasible in the 2020-2030 timeframe.

Testing Flight Paths for Collecting 3D LADAR Imagery of Inconspicuous Targets

Author: Mewett, David; Graham, Mark; Davies, Adam
Issue Date: Jul-2009
Citation: Mewett, D.T., M.D. Graham and A.H. Davies (2009). Testing flight paths for collecting 3D LADAR imagery of inconspicuous targets. In Anderssen, R.S., R.D. Braddock and L.T.H. Newham (eds) 18th World IMACS Congress and MODSIM09 International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand and International Association for Mathematics and Computers in Simulation, July 2009, pp. 1636-1642. ISBN: 978-0-9758400-7-8. http://www.mssanz.org.au/modsim09/E1/mewett.pdf

Abstract

A pilot study was performed to examine flight paths for an airborne foliage-penetrating Laser Detection and Ranging (LADAR) three-dimensional (3D) imaging system. Such systems form 3D images based on time-of-flight of laser photons, some of which pass through gaps in foliage or other partial obscurants such as camouflage nets. Hence the 3D image will contain partial information about any objects behind or underneath such obscurants. The obscurant can be removed from the image by only keeping points within some appropriate range, leaving a partial image of the hidden objects which may include targets of interest. An improved overall image can be formed by combining images taken from several different viewpoints, using knowledge of the LADAR sensors location at each viewpoint. In this study, we compared the overall 3D images obtained from an airborne LADAR system during different flight paths. The scene for each flight path consisted of a four-wheel-drive vehicle placed in a section of a eucalypt forest. Models for the vehicle and the individual trees were created in the 3D modelling software Maya, and exported as point clouds to be used in the general-purpose analysis software MATLAB. The overall forest scene was then assembled from the individual trees. The amount of light penetrating the foliage was determined at three different locations within the scene. On average, results were found to roughly agree with the prediction that light penetration scales with the sine of the angle from horizontal. Formation of LADAR images was modelled by determining the set of points in the scene that had a direct line-of-sight to the airborne sensor. This low-fidelity approach was taken because the aim of the study was to investigate ways of tasking the sensor system, rather than using the model as part of a hardware design process or a testbed for data processing algorithms. Since there is already a random effect due to line-of-sight through the forest canopy, it was decided that further random effects leading to false returns or missed returns would unnecessarily complicate the comparison between results from different flight paths. The flight paths in this study were intended to keep the sensor footprint directed at a known or assumed target area on the ground. One type of path was an arc centred at this location, with the sensor constantly directed sideways at an appropriate elevation. The other type of path went straight past the target area, with the sensor needing to be constantly redirected. Different scan spacings along the path were also investigated. It was assumed that the unobscured view from each flight path would be sufficient for the surveillance or reconnaissance task. So for each flight path, the Hausdorff distance was calculated as a measure of the difference between the 3D image of the target taken through the foliage and the corresponding unobscured image from the same flight path. No significant difference was found between results for the straight and arc paths, but the 3D images were closest to the unobscured views for the smallest scan spacing.

Benchmark Testing of Naval Threat Countermeasure Simulation (NTCS) Development from Version 2.4c to 3.2.

Report Number: DSTO-TR-2315
Author: Smith, S.E.
Issue Date: 2009-07
AR Number: AR-014-578
Classification: Unclassified
Report Type: Technical Report
Division: Maritime Platforms Division (MPD)
Release Authority: Chief, Maritime Platforms Division

Abstract

The Naval Threat Countermeasure Simulator (NTCS) is a commercial code accepted as the NATO standard for ship Infrared (IR) signature modelling. This code has undergone extensive development, in conjunction with measurement trials, since 1997. A set of benchmark test cases was developed to track the development of NTCS since 1997 paying particular attention to the effect on the computed IR signature of a test target. In this report, the results from these benchmark tests are presented for NTCS versions from 2.4c to 3.2. It will be shown that improvements to the NTCS code from version to version result in significant changes in computed IR signatures. In addition to code changes, other parameters such as choice of environmental data generation software (e.g. LOWTRAN/MODTRAN) and choice of solar scattering flag also influence the computed IR signature. Timing information was also assessed as part of this study and reveals increases in run-time requirements as NTCS has evolved. In light of these results, caution should be exercised when comparing results from different versions of NTCS. It is also recommended that details of the NTCS version and parameters used are specified when presenting NTCS results.

Executive Summary

The Naval Threat Countermeasure Simulator (NTCS) is a commercial code accepted as the NATO standard for ship infrared (IR) signature modelling. This code has undergone extensive development, in conjunction with measurement trials, since 1997. A set of benchmark test cases was developed to track the development of NTCS since 1997 paying particular attention to the effect on the computed IR signature of a test target. In this report, the results from these benchmark tests are presented for NTCS versions from 2.4c to 3.2. In addition to the changes resulting from different version, two other parameters within NTCS were also investigated. The first is the choice of environmental data generation software (e.g. LOWTRAN/MODTRAN) and the second is the choice of the solar scattering flag. These were included since they were changed or added to NTCS within the series of NTCS from 2.4c to 3.2. Improvements to the NTCS code from version to version result in significant changes in computed IR signatures. In addition to code changes, the parameters such as choice of environmental data generation software and choice of solar scattering flag also influence the computed IR signature. Timing information was also assessed during this study and reveals that the run-time requirements for NTCS have increased during the evolution of NTCS. It is recommended that caution is exercised when comparing results from different versions of NTCS. It is also recommended that details of the NTCS version and parameters used are specified when presenting NTCS results. Accurate comparisons of computed IR contrast signature data for different naval platforms can only be made reliably when the same NTCS version is used and the same background, environmental data generation software and solar scattering flag are selected.

Survey of Knowledge Representation and Reasoning Systems.

Report Number: DSTO-TR-2324
Author: Trentelman, K.
Issue Date: 2009-07
AR Number: AR-014-588
Classification: Unclassified
Report Type: Technical Report
Division: Command, Control, Communication and Intelligence Division (C3ID)
Release Authority: Chief, Command, Control, Communication and Intelligence Division

Abstract

Executive Summary

As part of the information fusion task we wish to automatically fuse information derived from the text extraction process with data from a structured knowledge base. This process will involve resolving, aggregating, integrating and abstracting information - via the methodologies of Knowledge Representation and Reasoning - into a single comprehensive description of an individual or event. This report surveys the key principles underlying research in the field of Knowledge Representation and Reasoning. It represents an initial step in deciding upon a Knowledge Representation and Reasoning system for our information fusion task. We find that although first-order logic is a highly expressive knowledge representation language, a major drawback of the logic as a Knowledge Representation and Reasoning system for our information fusion task is its undecidability. Moreover, most first-order automated theorem provers are not designed for large knowledge-based applications. Modal logics are gradually receiving more attention by the Artificial Intelligence community, but research in modal logics for knowledge representation still has a long way to go. A production rule (expert) system is viable as a Knowledge Representation and Reasoning system, but these systems are optimally suited for small, specific domains. To build an intelligence expert system we would require expert knowledge in pretty much everything. Frame systems are limited in their expressiveness, and moreover - in regards to knowledge representation - have been superceded by description logics. Semantic networks are excellent for taxonomies, but are not particularly suitable for our information fusion task. On a more positive note, description logics are currently very popular and are actively being researched. They are (in the most part) decidable and their open-world semantics would allow us to represent incomplete information. A further advantage is the availability of Semantic Web technologies. Description logics are still limited however; for our task, wed need to look at very expressive logics which might lose us decidability.

Giselle: A Mutually Orthogonal Triple Twin-loop Ground-symmetrical Broadband Receiving Antenna for the HF Band.

Report Number: DSTO-TR-2321
Author: Martinsen, W.
Issue Date: 2009-07
AR Number: AR-014-584
Classification: Unclassified
Report Type: Technical Report
Division: Command, Control, Communication and Intelligence Division (C3ID)
Release Authority: Chief, Command, Control, Communication and Intelligence Division

Abstract

This report describes development of a tri-axial mutually orthogonal broadband twin-loop receiving antenna for the HF band. The three twin-loops have been arranged so that they exhibit the same distributed parameters between themselves and ground. The upper frequency limit of the antenna is discussed and a method for extending the low frequency cut-off is presented. The antenna noise factor is calculated from measured data.

Executive Summary

Traditional mutually orthogonal tri-axial loop antennas have distributed parameters to the ground that are not consistent between the three loops. This non-symmetrical characteristic adds complexity to the analysis of signals received from each of the loops. Also, the distributed inductance (L) and capacitance (C) of each loop form a resonant circuit limiting the loops usefulness for broadband work. The tri-axial twin-loop antenna design presented in this report has the same distributed parameters to ground on all three loops (ground-symmetrical) easing the analysis burden on the received data. The final version of the antenna presented can cover the complete HF band and is ideal for studying the polarisation of received signals with the view of mitigating HF polarisation fading. The inherent noise produced by the Giselle antenna is less than the expected man-made noise for a quiet rural site; therefore the Giselle antenna can also be used as a compact triaxial polarisation diversity surveillance antenna for the whole of the HF band. It is capable of discriminating between locally transmitted ground wave signals and those transmitted at some distance and received via sky-wave by monitoring for any signs of rotation in the received signals polarisation.

Synthetic Electronic Imaging System.

Report Number: DSTO-TN-0903
Author: Ide, K.M.; Jarvis, B.J.; Lucas, M.A.
Issue Date: 2009-07
AR Number: AR-014-574
Classification: Unclassified
Report Type: Technical Note
Division: Weapon Systems Division (WSD)
Release Authority: Chief, Weapons Systems Division

Abstract

The Synthetic Electronic Imaging System employs electronic components to combine multiple images from a plurality of cameras which are processed with inertial data from the vehicle on which the system is mounted to yield stabilised video images without resorting to complicated optics or a stabilised platform. It was devised as an alternative to stabilised ball turrets fitted with electro-optic and infrared cameras. Intended as an imaging system for Unmanned Aerial Vehicles (UAV), it may be employed in any manned or Unmanned System (UMS) where situation awareness is aided by the use of an imaging system. This report describes the development of the Synthetic Electronic Imaging System and assembly of a simple concept demonstrator in 2005.

Executive Summary

Conventional ball turret imaging systems are mechanically complex requiring continued calibration and maintenance. Hence, their purchase and support involves significant costs. The dimensions and weight of a ball turret demand an airframe with significant payload capacity. These restrictions led the authors to develop the Synthetic Electronic Imaging System. It is a highly capable alternative but without the complexity, cost and support necessary for a comparable ball turret imaging system. The Synthetic Electronic Imaging System employs electronic components to combine multiple images from a plurality of cameras which are processed with inertial data from the vehicle on which the system is mounted to yield stabilised video images without resorting to complicated optics or a stabilised platform. A full field of view wide angle composite image is displayed on one monitor with a box overlay representing the region of interest. A second monitor shows a telephoto image within the designated region of interest. As the operator moves the region of interest, images in the second display are updated in real-time. The two complementary video streams provide an excellent aid to situation awareness and analysis. The two video channels are transmitted to the Ground Control Station as television images requiring very low bandwidth. Operators can time-slip the video images by using Digital Video Recorder software controls for review and analysis. Frames that merit further analysis or examination can be downloaded from the remote vehicle as a series of still images with the maximum resolution of the sensor. Intended as an imaging system for Unmanned Aerial Vehicles, it may be employed in any manned or Unmanned System where situation awareness is aided by the use of an imaging system. This report describes the development of the Synthetic Electronic Imaging System and assembly of a simple concept demonstrator in 2005.

Thermodynamically Consistent Decoupled Shear-Volumetric Strain Model and CTH Implementation.

Report Number: DSTO-TR-2299
Author: Resnyansky, A.D.
Issue Date: 2009-06
AR Number: AR-014-552
Classification: Unclassified
Report Type: Technical Report
Division: Weapon Systems Division (WSD)
Release Authority: Chief, Weapons Systems Division

Abstract

Many hydrocodes, such as LS-DYNA and CTH, require the decoupling of the shear from volumetric response in a material model used. A constitutive model is formulated, which decouples the responses of a rate sensitive material. Basis of the model is a general Maxwell-type viscoelastic model, which, however, is not originally decoupled and, thus, not suitable for implementation in the hydrocodes. The formulation provides the thermodynamic consistency for the case of small deviatoric elastic deformations and unrestricted volumetric response. A schematic of implementation in CTH is briefly described. Numerical illustrations demonstrate agreement of the CTH calculations with calculations available in the literature.

Executive Summary

The development of advanced weaponry demands science and industry pay attention to novel energetic materials and materials with enhanced protective properties, including composite materials, porous and multi-phase mitigants, advanced materials manufactured with nanotechnology, etc. The response of these materials needs to be predicted and this raises new challenges for the area of computer modelling of the material response to extreme pressure and temperature. Advanced shock physics codes are a solid basis for modelling efforts. Among them hydrocodes are the most relevant to the level of loads and temperatures because they are able to deal both with the material behaviour in conditions of hydrodynamic flow and with the elastic-plastic deformation at moderate loads when the material strength is important. Hydrodynamic (strength negligible) flows due to extreme loads are typical for materials subject to the hyper-velocity impact by shaped charge jets and for materials in direct contact with detonating energetic materials. The effect of these conditions on enhanced materials requires consideration of multi-phase behaviour with phase transitions, however, such models are yet to be developed. The elastic-plastic (strength relevant) deformations prevail in materials at the load levels typical of high-velocity fragmentation impact or of blast effects from charges in a certain proximity to the target. The elastic-plastic response under these conditions is of the constitutive type, i.e., the materials manifest rate sensitivity and require advanced modelling approaches. In summary, the development and use of advanced models in commercially available hydrocodes is a great challenge. The modelling capability in DSTO is supported by several hydrocodes. The LS-DYNA3D hydrocode (originally a Lagrangian code) has been employed for a number of years in DSTO. It has proved its efficiency for modelling the weapon and terminal effects in problems involving moderate deformations and requiring a good resolution of contact material interfaces. A user-defined material model is relatively simple to incorporate within the DYNA interface though no well-documented implementation procedures are established. A number of material models have been implemented in this code in DSTO exploring the constitutive model capabilities for: i)conventional materials subject to high-velocity fragment impact [1] and materials involved in the shaped charge jet formation, when studying the weapon effects of the two-stage follow-through grenade weapon [2], ii)composite materials subject to ballistic impact for the Army Reconnaissance Helicopter project [3],iii)concretes subject to hyper-velocity impact, when studying the target effects against the multi-stage weapon threats [2, 4], and iv)materials manifesting multi-phase features, when simulating the underwater explosion in a Navy project [5]. However, for the problems such as counter-IED (Improvised Explosive Devices) dealing with large deformations, intensive flows and high multi-phase/multi-material mixing a Eulerian code is more suitable. Therefore, the present work is attempting to gather the implementation experience for the CTH hydrocode developed by Sandia National Laboratories in the US. Implementation procedures for the code are quite well documented. The implementation difficulties are mainly associated with the necessity for the user to intervene in a number of entry points of the code, the number of which and the places of entry depend on the nature of the model to be incorporated. Due to the release features of the code not all necessary points of entry may be easily accessible, this is another challenge for the user. The present work adapts a rate sensitive strength model for conventional materials, which has been published earlier in the literature, to a form decoupling the shear and volumetric responses. The present formulation is in agreement with the CTH implementation requirements and it preserves the thermodynamic consistency of the model. In addition, this formulation suggests a general thermodynamically consistent way of decoupling between the shear and volumetric responses of a material, which might be useful for the development of advanced strength models requiring this decoupling. The model along with its implementation is tested with a number of impact and shaped charge problems. The CTH calculations are compared with numerical solutions and experiments available in the literature and a good agreement is observed. Thus, the present work establishes the model implementation capability in DSTO for the CTH hydrocode.

Acoustic Electric Feedthrough Demonstrator Mk-I.

Report Number: DSTO-TR-2296
Author: Moss, S.; Konak, M.; Phoumsavanh, C.; Tsoi, K.; Powlesland, I.
Issue Date: 2009-06
AR Number: AR-014-549
Classification: Unclassified
Report Type: Technical Report
Division: Air Vehicles Division (AVD)
Release Authority: Chief, Air Vehicles Division

Abstract

This report outlines the development and characterization of the DSTO Acoustic Electric Feedthrough (AEF) Laboratory Demonstrator Mk-I, which passes power ultrasonically through a 5 mm thick aluminium plate. The AEF approach is being explored as a potential means of wirelessly powering in situ structural health monitoring systems embedded within aircraft and other high value assets. The demonstrator's assembly and subsequent characterisation is discussed, and compared with performance predictions made using numerical modelling. Improvements are suggested which will be implemented in the proposed AEF Demonstrator Mk-II, a system capable of passing both power and communications ultrasonically through a metal plate.

Executive Summary

This report has examined the modelling, characterization and manufacture of an Acoustic Electric Feedthrough (AEF) Laboratory Demonstrator Mk-I with the aim of developing a system capable of passing power and communications through the aluminium skin of an aircraft using ultrasound. An AEF arrangement operates via two piezoelectric elements, located collinearly on opposite sides of a metal plate. One piezoelectric element is excited at its thickness mode anti-resonant frequency which then generates ultrasound which passes through the metal plate, and is received by a second element located on the opposite side of the plate. A numerical model of the AEF demonstrator was developed and used to characterize the behaviour of the system; predictions from the numerical model were confirmed by experiment. Real power transfer efficiency was found to be 30% for the demonstrator. In particular the AEF power loss mechanisms were explored, and the major losses were heat generation due to viscous loss in the piezoelectric elements. An AEF Laboratory Demonstrator Mk-II that can transmit power (at the measured power transfer efficiency) and two-way communications is proposed.

Australian Defence Force Nutritional Requirements in the 21st Century (Version 1).

Report Number: DSTO-GD-0578
Author: Forbes-Ewan, C.
Issue Date: 2009-05
AR Number: AR-014-525
Classification: Unclassified
Report Type: General Document
Division: Human Protection and Performance Division (HPPD)
Release Authority: Chief, Human Protection and Performance Division

Abstract

Executive Summary

This report addresses the determinants of military nutritional requirementsthat is, the relevant variables that determine the types and quantities of foods necessary to support ADF training and operations. It also examines the current state of knowledge about nutritional requirements, includes recommendations on nutritional standards for ADF rationing systems, and suggests areas of research that will help fill the gaps in our knowledge. This is the second revision (i.e. the third iteration) of Australian Defence Force Nutritional Requirements in the 21st Century. However, although the two earlier documents were internal reports, i.e. they were not published in the DSTO Report Series, they were used by the Defence Materiel Organisation (DMO) to set standards for ADF combat ration packs (CRP) and by DSTO to assess the nutritional adequacy of CRP and of fresh-feeding systems. The recent publication by the National Health and Medical Research Council (NHMRC, 2006) of Nutrient Reference Values for Australia and New Zealand provided an incentive and an opportunity to revise and update this report. It is intended to be a living documenti.e. it will be available only in electronic form and not in hard copyso it can be updated whenever new information becomes available. The 2009 Defence White Paper (Department of Defence, 2009) imposes on the ADF a need for self-reliance, a high level of mobility, and an ability to operate in all terrains, climatic conditions and social situations. Therefore, there is a need for rationing systems (particularly ration packs) that will sustain troops during short-term, high-intensity operations (e.g. up to 72 hours) and also a need for rationing systems that will support long-term, low-intensity operations (lasting many weeks). In each case, operations could be conducted in the heat, cold and/or at altitude, in rainforest, desert or temperate regions. Physical activity levels and gender are the two major determinants of nutritional requirements of ADF members, with age, stature, climate, altitude, terrain, and individual variation playing relatively minor roles. Each of these determinants exerts its effects predominantly via an influence on energy expenditure. Females have approximately 70 75% of the energy requirement that males have for the same activity. The only substantial purely gender-related difference in nutritional requirements is a greater need for iron by female ADF members. However, the unique requirements of adolescent ADF members should be taken into account in messes where adolescents constitute a substantial proportion of the ADF population being rationed. Adolescent ADF members have a slightly greater need than adults for energy for growth, and generally also for physical activity. Adolescents also have a significantly greater need than adults of the same gender for some micronutrients, particularly calcium (males and females), phosphorus (males and females) and iron (males only). The nutritional requirements discussed for ADF members in this document will not necessarily apply to each individual. Although the ADF population is relatively homogeneous, there will always be some variation between individuals. This variation comes from two main sourcesdifferent body size and composition, and individual genetic variation in metabolism. However, largely because requirements will vary normally (in the statistical sense) about the mean, it is considered appropriate to base nutritional standards on the nutritional requirements of average male and average female members of the ADF. The extent of over-nutrition (i.e. excess body fat levels) in the ADF needs to be investigated. The Australian Defence Health Status Report (published in 2000) found that 57% of ADF members were above the healthy weight range. Recommendations are made in the present report on how improvements may be made to monitoring and reporting of body fat levels and determining risk of ill-health through the addition of a simple measurementwaist circumferenceto existing regular medical examinations. It appears to be a near-universal finding that troops under-eat on operations when rationing is by CRP. When nutrient intake is less than ideal, the nutritional status of a subject prior to the period of low nutrient intake itself becomes a determinant of subsequent nutritional status. There is evidence from the military scientific literature (both Australian and overseas) that young service people are entering military service with suboptimal nutritional status. The potential for this to impact adversely on health and performance can only be overcome by improvements in nutritional quality of diet during service. This implies a strong need for both availability of highly-nutritious food and guidance to ADF members on appropriate food selections to maximise nutritional status. DSTO has conducted studies to determine the energy expenditure (and therefore nutritional requirements) of (predominantly male) ADF members across a wide range of land-based, and a smaller range of sea-based military activities. These results are summarised in Tables 1 and 2 of the present report. Knowledge gaps can be filled by conducting research on ADF groups not previously studied. There is also scope for resuming the development of an expert system that will allow commanders to determine the food and water needed to sustain troops in particular operational situations. It is concluded that for the purposes of setting nutritional standards, the ADF can be divided into four population groupsadult males, adult females, adolescent males and adolescent females. Further, adult male ADF occupations can be conveniently assigned to five distinct categories of energy expenditure, while four categories apply to occupations involving adult females and adolescents. The highest category (Category 5) is believed to be a special case, applying largely to males attempting selection to the Special Air Service Regiment. Therefore, only categories 14 are regarded as being of practical significance to the vast majority of ADF rationing. However, further studies on the energy expenditures associated with SF training and operations are needed to confirm or alter this belief. Also, it is suggested that during a period of re-feeding following sustained under-consumption (e.g. when troops have been fed with combat ration packs for more than two weeks while engaging in very vigorous physical activities), Category 5 entitlements are appropriate for the period of re-feeding. Although there is a reasonable correlation between the defined categories of ADF activity levels and those of the NHMRC (2006), they do not correspond exactly. Consequently, it is recommended that DSTO attempt to add a category of energy expenditure (perhaps designated extreme activity) to the six existing NHMRC physical activity levels. Nutritional quality of the diet of ADF members is critical in ensuring that optimal performance can be maintained as long as possible. This quality is in terms of macronutrients (protein, fat and carbohydrate), micronutrients (vitamins, minerals and trace elements) and dietary fibre. Carbohydrate is considered to be the most important macronutrient for vigorous physical activity, with fat being of value mainly for acceptability. The important role played by protein in recovery from vigorous physical activity has been recognised only relatively recently. It is recommended that the standard for protein be set at 1520% of total energy for situations involving light physical activity (Category 1), with the range of percentage contributions decreasing linearly as energy expenditure increases (from 1419% for Category 2 to 1114% for Category 5). Conversely, the percentage of energy derived from carbohydrate should increase linearly with increasing physical activity from a range of 5055% (Category 1) to 5863% (Category 5), at the expense of fat (decreasing linearly from 2735% (Category 1) to 2331% (Category 5). The recommended ratios of protein to fat to carbohydrate (P:F:C ratios) are shown in Table 4. As indicated in a footnote to Table 4, the only situation in which it is recommended that carbohydrate should provide more than 63% of energy is when operations are conducted at high altitudehere it is recommended that the P:F:C ratio should be approximately 15:20:65 respectively. There is preliminary evidence that not only the quantity, but also the quality of carbohydrate may impact on both performance and health. Further research is warranted on the potential to enhance nutritional status by varying the glycaemic index and increasing resistant starch in rations (particularly in combat ration packs). There is also scope for conducting research on the impact of combining protein with carbohydrate to enhance recovery from vigorous physical activity. The previous two iterations of this report included Recommended Military Dietary Intakes (RMDIs) for all nutrients that had been assigned Recommended Dietary Intakes (RDIs) in 1991 by the NHMRC. The RMDIs corresponded very closely to the RDIs. In 2006 the NHMRC published Nutrient Reference Values (NRVs) to apply to the population of Australia and New Zealand. These differ, often substantially, from the 1991 recommendations. It is recommended that the RDIs (or Adequate Intake if an RDI has not been established) of the NHMRC (2006) be adopted as Military Recommended Dietary Intakes (MRDIs) for all nutrients other than thiamin, riboflavin, niacin, vitamin B6, protein and sodium, and also for total energy. The reasons for these exceptions are detailed in the body of this report. It is also recommended that MRDIs be defined for carbohydrate, even though NRVs were not published by the NHMRC for carbohydrate. It is recommended that military-specific Estimated Average Requirements (MEAR) be calculated for the Bgroup vitamins thiamin, riboflavin, niacin and vitamin B6 as 70% of the respective MRDIs. Finally, it is argued that nutritional standards should take into account age (adult versus adolescent), gender and activity level. Table 5 shows the MRDIs for adult males for five categories of physical activity; Tables 68 show the MRDIs for the adult females, adolescent males and adolescent females of the ADF for four categories of activity. Nutritional standards are recommended for general purpose (i.e. not mission-specific) CRP. These are based on Category 3 requirements for energy (~16 MJ), protein and carbohydrate for adult males and the MRDI that constitutes the worst case situation for each micronutrient (i.e. the sub-group that has the greatest requirement for each specific micronutrient) for ADF members working at Category 3 That is, the nutritional requirements of practically all ADF members working at Category 3 will be met by the basic ration pack if it is eaten in its entirety. Table 9 details the recommended nutritional criteria for general purpose ration packs. Further, it is recommended that fortification to three times the MRDI should occur for four key vitaminsthiamin, riboflavin, vitamin B6 and vitamin Cto counteract storage losses and the discarding of ration pack items. It is also recommended that more research be conducted into vitamin stability during storage of ration packs, and on how bioavailability of micronutrients from combat ration packs affects nutritional status of ADF members. It is recommended that a small range of mission-specific ration packs be developed; that consideration be given to adopting a modular, just-in-time process for procuring, packing and distributing CRP; and that investigation be conducted into the need for, and most appropriate form of a group-feeding pack. Recommendations are provided on how entitlements to fresh rations should be determined. Tables 58 show the MRDIs that apply for homogeneous groups of ADF members (i.e. all members are of the same gender and age groupadult or adolescent). For a mixed ADF population (a mixture of genders and age groups) the entitlements to energy and macronutrients for fresh feeding should be based on the number to be fed and the MRDIs that apply to the worst case situation (i.e. the sub-group that has the greatest requirement for each specific nutrient). Table 10a shows these recommended entitlements. Appendix B provides an example of how the entitlements to total energy can be determined for a mixed ADF population to be fed freshly-cooked food at a mess. In designing ration scales for fresh feeding, it is recommended that a basic scale be devised based on the MRDIs for energy, protein and carbohydrate for adolescent males working at Category 1. For the remaining nutrients, the MRDI that applies to Category 4 physical work output for the population sub-group that constitutes the worst case situation should apply. Table 10c shows the recommended nutritional basis of the basic fresh-feeding scale. Allowance should also be made for inevitable food discarding. It is suggested that this allowance be 15%i.e. food availability should be 15% above the estimated requirement. To feed troops working above Category 1, it is recommended that between-meal snacks be devised in modular form, with each module providing 12 MJ. Dietary modelling should be conducted to determine the ability of real world diets based on these entitlements to meet the MEARs of ADF members. Table 10b shows the nutritional criteria for this dietary modelling for mixed population groups of ADF members. Table 10d shows the nutritional criteria for modelling the adequacy of the basic ration scale (Category 1, mixed population). In assessing the nutritional adequacy of intake of ADF groups it is also the MEARs that apply. Table 10b applies in relation to assessing the adequacy of intake for mixed population groups; Tables 1114 apply to the four categories of homogeneous groups of ADF members. When determining the adequacy of nutritional intake of an individual ADF member, it is appropriate to use the MRDIs applicable to that individuals population group and activity category (Tables 58 apply). The recommended entitlements in this report are also considered to be an appropriate basis for the development of military core food groups and a military guide to healthy eating. It is also suggested that the nutritional entitlements supporting hot-boxed meals (used for fresh feeding in the field) should be based on the appropriate work category (3 or above) for adult male ADF members. The implications of under-consumption in the field, specifically when feeding is by CRP, are addressed. The origins of negative energy balance, how this affects military performance, and steps that may be taken in an attempt to overcome any perceived problems are critical factors affecting nutritional status of ADF members. It is concluded that previously well-nourished troops should suffer no decrement to performance for at least 16 days when rationing is solely by CRP. It is also concluded that more research is needed in this area. Following an extended period of negative energy balance, it may be appropriate to aim for a recovery period equal to about half the period of negative energy balance. Until further information is available, it is considered prudent to attempt to limit the rate at which recovery is attained to a maximum of ~8 MJ per day. That is, the tentative recommendation is that the excess of intake over expenditure during the recovery period should be no more than 8 MJ per day. It may also be appropriate to seek advice from military Medical Officers on how recovery feeding can be safely conducted if troops have undergone an extensive period of severe under-consumption.