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4 Basic Research OVERVIEW Since FY00, Code 353 has been supplying Navy Basic Research (6.1) funds to support Marine Corps future technology capabilities, as the Marine Corps itself has no allocated 6.1 funds. The Marine Corps Basic Research Focus Program, referred to throughout this report as the Basic Research portion of the Marine Corps Science and Technology (MCS&T) program, seemed to the committee to be a useful program of research with much interesting science that was presented with enthusiasm. The presenter impressed the committee with the breadth and depth of his understanding of the many projects both the technologies and the programmatics. Basic Research, though relatively new in the MCS&T program, is likely to serve the Marine Corps well if it is given the right opportunities and adequate funding for transitioning into future Marine Corps capabilities. Overall Findings and Recommendations Code 353's Basic Research appears to be a useful addition to the larger Navy 6.1 program. The Marine Corps 6.1 program manager s physical location at UNK ~eaciquarters enables close interaction with other well-qualified scientific officers. However, leveraging appears to the committee to be handi- capped by the limited 6.1 funding allocated to Marine Corps needs. Some of the work presented as basic research, although potentially useful, did not appear to the committee to be "basic." Much the same impression was noted in the NSB's earlier review of the MCS&T program. Basic research is intended to answer fundamental questions relating to future developments that are not yet fully formulated. It might also be used to assist development work that is ~ 1 1 1 , , BITT 1 1 , 1 1 1 , , - 1Naval Studies Board, National Research Council. 2000. 2000 Assessment of the Office of Naval Research's Marine Corps Science and Technology Program, National Academy Press, Washington, D.C. 83

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84 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM handicapped for want of some fundamental knowledge. In both cases feedback from 6.2 and 6.3 to 6.1 is essential to identify critical research areas. Basic Research could also coordinate better when it comes to transitioning results into 6.2 and 6.3 applications. Marine Corps personnel could guide strategic planning of the 6.1 program by steering it not to projects but to technology areas likely to impact long-term combat needs. In addition, to be effective despite its size, a Marine Corps-oriented 6.1 program must be leveraged as much as possible. Code 353 is well aware of the need for leveraging, but Basic Research appears to the committee to be handicapped by the low funding levels. Recommendation. Code 353 should broaden its Basic Research focus areas to create a more robust and sustainable series of efforts. The new focus areas should result from a careful assessment of Marine Corps needs. A suggested reorganization of focus areas and sample topics is provided in Table 4.1. In addition, Code 353 should strive to set aside a small amount of uncommitted 6.1 funds (perhaps a few hundred thousand dollars) to foster additional flexibility in program support and to enable quick looks (e.g., a few months to a year) at new, unforeseen, novel concepts that arise from time to time. Code 353 should establish a formal mechanism to allow continuing feedback of 6.2 and 6.3 findings to the 6.1 office to help identify fruitful new areas of 6.1 research. Code 353 should work aggressively to expand the funding base for Basic Research so that a coherent set of significant Marine Corps-related projects can be supported. The Marine Corps should be involved in all aspects of the Code 353 research and development process, including the strategic development of the Basic Research part of the MCS&T program. In support of this goal, Code 353 should participate in (or encourage the Marine Corps leadership to participate in) meetings of the Defense Committee on Research, which currently has representatives from all the Services except the Marine Corps. As a means of fostering leveraging with basic research efforts outside ONR, Code 353 should regularly review the biennial Department of Defense Basic Research Plan.2 PROJECTS REVIEWED Code 353's Basic Research program is currently organized into eight research areas and contains 29 projects. The research areas were chosen because they are critical areas that could be of use to the individual marine rather than for platforms or combat systems. These areas are reviewed here in the order they were presented to the committee: Communications. Lightweight power sources Information efficiency, Sensing, Human sensory enhancement, Land mine detection, Laser eye protection, and Energetic materials. 2Office of the Deputy Under Secretary of Defense (Science and Technology). 2002. Basic Research Plan (BRPJ, Depart- ment of Defense, Washington, D.C.

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BASIC RESEARCH TABLE 4.1 Suggested Reorgan 85 ization of Basic Research Focus Areas and Sample Topics Focus Area Sample Topics C4I Energy Sensing Materials Human Factors Oceanography and Environment Weapons Ad hoc wireless networking Beyond-line-of-sight communications Short-range, high-density, low-power communications Antijam protection Information assurance Lightweight power sources and rechargeable electric storage devices Energy-efficient devices and techniques High-energy-density storage Sensors for situation awareness (pre-attack) Sensors for damage assessment (post-attack) Sensors that work in an urban environment Mine detection: fundamental physical mechanisms and phenomenology in surf and on land Unmanned surveillance/reconnaissance vehicles Non-communications use of ultrawideband radar Materials and structures Sensing materials Corrosion prevention Non-lethal weapons Psychological profiling to identify potential terrorists Human sensory enhancement Shallow-water oceanography: bottom structure in the surf zone, bottom interactions, and surf and current characteristics Effects on warfare of hostile or unusual climates (weather) Enhanced lethality Aim-point accuracy After a brief discussion of each project, the committee's findings and recommendations are pre- sented below. Communications Research in communications supports the development of capabilities to ensure robust communica- tion links that will support the individual warfighter. As it is currently constituted, communications research focuses on bringing wireless capabilities to a variety of sensors while also developing the necessary supporting network technologies. A key element is the explicit recognition of the limits imposed by the finite energy capacity of battery systems. There are only so many "bits per battery." Addressing this limitation from the start makes very good sense.

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86 Ultrawideband Radio Ranging Studies 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM Ultrawideband (UWB ~ radios could offer the Marine Corps a communications capability with a low probability of being intercepted and jammed, and they might also be useful in difficult conditions, such as MOUT. Radio-ranging studies will be conducted with varying electromagnetic environments and signal path obstructions, to support the development of ranging algorithms for minimizing the effects of false signals or noise. Although research on UWB radios has been conducted for a number of decades, very few real systems based on this approach have been developed or deployed, primarily because other highly developed competing approaches (direct-sequence, spread-spectrum communications, for ex- ample) have been adopted by the public communications sector. However, because it promises to place the entire radio on a single, low-power chip, UWB communication has found renewed favor in the wireless world. Findings and Recommendation. This project focuses on developing empirical models for ultra- wideband channels. These models will be critical in establishing reliable UWB links, particularly in developing the necessary receiver algorithms. The committee notes a lack of integration across ONR and other potential sources of research on UWB radios. A number of alternative wideband models already exist but were not mentioned. Recommendation. Code 353 should compare the models emerging from the ultrawideband radio ranging studies with existing UWB models. Channel Coding and Estimation for Ultrawideband Impulse Radios Ultrawideband radio receivers must have sophisticated capabilities for estimating the time of arrival of short-duration pulses. In the laboratory, this is a relatively straightforward procedure. However, in any real-world application, multipath and channel dispersion makes the problem of identifying time of arrival to a resolution of nanoseconds a significant technical challenge. Findings and Recommendation. The channel coding and estimation project aims to use previously derived channel models to develop coding. Channel coding and estimation techniques in use for 30 years in conventional narrowband communication systems must be extended to ultrawideband systems if such systems are to have any meaningful capability. Recommendation. Code 353 should incorporate channel coding and estimation into a test system for thorough evaluation of the channel coding and estimation for ultrawideband impulse radios. Low-Power CMOS Implementation of Ultrawideband Impulse Radios For UWB radios to have any future value to the Marine Corps, they will have to be small in size and consume little power. This project aims to develop a basic UWB radio system contained in its entirety on a single chip using complementary metal oxide semiconductor (CMOS) circuit technology. The design application is for short-range (less than 5 meters) data communications at a scalable bit rate (100 to 100,000 bits per second). Findings and Recommendations. UWB radios remain a complex and difficult area of research. The

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BASIC RESEARCH 87 low-power CMOS implementation project is important for developing a prototype UWB radio that can be used later for critical Marine Corps evaluation and testing. The current plan, which is nearing completion, is to develop a prototype CMOS chip UWB transceiver. The results of this effort should be integrated with related Code 353, other Service, and industry efforts aimed at producing similar UWB technologies. Even with the successful completion of the single-chip prototype, several questions remain about efficient implementation of the receiver algorithms necessary for UWB radios. The committee noted that this issue is alleviated, in part, by the radio's planned short-range operation. The committee also expressed concern that the stated goals of this effort, while interesting in their own right, were not consistent with the criteria for a Basic Research project. The committee observed that prototype development of integrated systems is typically supported through 6.2 or 6.3 funding. --D ' Recommendation. Code 353 should transition further work on single-chip implementation of ultrawideband radios to a 6.2 or 6.3 program as soon as possible. Recommendation. Code 353 should ensure that follow-on ultrawideband radio projects appropri- ately monitor relevant industry, other Service, and ONR efforts to produce similar radios. Energy-Efficient Wireless Networking Energy budgets have been an important part of wireless communications system design, especially for the cellular telecommunications industry. The energy-efficient wireless networking project will develop a model for a mobile ad hoc network that allows independent evaluation of the resulting energy needs of the nodes, based on systematic alteration of network and node behaviors. In this manner, the operational consequences of network design for node power can be assessed more realistically. Informa- tion efficiency is important not only to the military but also to the much larger wireless commercial industry. Findings and Recommendation. The energy-efficient wireless networking project aims to extend work initiated under a DOD Multidisciplinary University Research Initiative (MURI) programs by introducing finite energy budgets for each mobile node as well as modeling network response to the feedback between receiver and transmitter, event-driven network loading, interference from other nodes, and so forth. Because this project is a new start for FY03, it is difficult to draw any conclusions about progress, although the project seems promising in its stated goals and methods. Recommendation. Code 353 should continue the energy-efficient wireless networking project as planned and carefully monitor related industry and other Service programs in this area. Game Theoretic Analysis of Radio Resource Management for Ad Hoc Networks Wireless ad hoc networks have been the subject of intense study over the last decade, with a variety of approaches taken to determine their efficacy and robustness. Game theory has been used to study, model, and optimize networks, and ad hoc networks can benefit from extensions of that earlier work. 3Low Energy Electronics Design for Mobile Platforms, DOD MURI.

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88 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM Findings and Recommendation. The game theoretic analysis of radio resource management for ad hoc networks project started in early 2003 and has not shown any novel results to date. Recommendation. Code 353 should continue the game theoretic analysis of radio resource manage- ment for ad hoc networks project, as planned. MEMS-Based Athermal Modulating Retroreflector Free-space optical communications have long promised low-power, high-data-rate digital com- munication links, yet many developmental challenges remain and the actual applications have been few. In particular, current methods to create free-space optical retroreflectors have been based on semicon- ductor materials that have significant temperature variability, which severely limits their potential application in uncooled low-power systems. Findings and Recommendation. The MEMS-based Thermal (temperature independent) modulating retroreflector project proposes a novel concept a MEMS device that, through the small, controllable reflections of an array of tiny MEMS mirrors, is capable of modulating a reflected beam of light. The primary application is for line-of-sight, high-data-rate communications with sensors by individuals who have limited energy capacity. An additional benefit is covertness for the sensor or the individual. The device itself could be very low power, since there is no need to generate light by the information sensor. The system would be interrogated by an external source and would act passively, impressing informa- tion as modulations on the reflected beam. This is an interesting project, with obvious potential benefits for the Marine Corps. Recommendation. Code 353 should continue the MEMS-based Thermal modulating retroreflector project, as planned. Lightweight Power Sources Today's individual marine is increasingly dependent on electronic devices, which demand an in- creasing supply of portable electric energy. This effort addresses fundamental issues in several of the most promising technology options rechargeable batteries, fuel cells, and biomechanical energy and investigates the modeling of power systems of all kinds. High-Energy-Density, Rechargeable, Thin-Film Batteries for Marine Field Operations The ability to store portable electrical energy is essential for marines in field operations, where energy is required for the operation of sensory enhancement equipment, automatic weapons, communi- cations systems, and so on. The weight of these batteries is a major problem. The lithium polymer battery is an attractive option for the distributed power storage needs of marines in field operations, because it has projected practical energy densities of greater than 300 Wh/kg, low safety risks, and great flexibility in battery configuration. However, significant materials and processing challenges must still be overcome to achieve these performance advantages. Recently, efforts have shifted to a graft copoly- mer electrolyte as a practical approach for achieving the favorable properties of both large-scale rigidity and small-scale liquidity that were not achieved by earlier nanocomposite approaches. Test results

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BASIC RESEARCH 89 indicate that thin-film batteries with energy densities approaching 400 Wh/kg could be fabricated using a graft co-polymer approach. Findings and Recommendation. Work on rechargeable batteries appears to have resulted in materials advances and a fabrication technology that offer a significant increase in energy density over today's batteries. However, the data presented were not clear about what was included in the energy density analysis. This project was planned to end in mid-FY03. Recommendation. Code 353 should continue the rechargeable battery development project at the 6.2 or 6.3 level to prepare it to the point that it can be evaluated by industry for commercialization. Fuel Cells for the Direct Electrochemical Oxidation of Strategic Fuels The Department of Defense would very much like to standardize on JP-8 as the single source of energy on the battlefield. Research on fuel cells is motivated by the complexities of reforming fuels such as JP-8 to produce hydrogen for fuel cell consumption. Solid-oxide fuel cells have the potential for eliminating or reducing the need for a separate, energy-intensive reforming step by direct insertion and oxidation of hydrocarbon fuels at the anode. This project was initiated to address key issues associated with expanding the applicability of solid-oxide fuel cells to directly oxidize logistically available fuels such as JP-8. Findings and Recommendations. The fuel cells research project has been very successful. Early on, a significant breakthrough was achieved in the direct oxidation of logistic fuels. It was discovered that substituting ceria and copper for the nickel catalyst on the anode facilitated the oxidation reaction without catalyzing the formation of anode-clogging graphite. This breakthrough in the ability to directly oxidize a hydrocarbon fuel in a solid oxide fuel cell represents a significant contribution to the fuel cell state of the art. Based on these results, DARPA has initiated a major effort to develop a complete JP-8- fueled prototype fuel cell system utilizing the anode catalyst developed by the Marine Corps/ONR. In addition, the contractor has entered into agreements for commercialization of the technology. Recommendation. Code 353 should continue, and if possible expand, support for an examination of the effects of sulfur and other JP-8 impurities on the coking, performance, and stability of the catalyst. Recommendation. Code 353 should investigate novel means to reduce the sulfur content of JP-8 to a level acceptable for input into fuel cell devices. This effort should aim to enable the use of high-sulfur- content indigenous fuels, which in turn would ease the logistics burden by enabling use of whatever fuels are available during a conflict. Recommendation. Code 353 should continue to participate in DARPA program reviews and, to- gether with the Army, should look into transitioning the DARPA JP-8 prototype fuel cell to an FNC program. Polymer-Moderated Aluminum Anode In comparisons of the energy densities of batteries, aluminum/air cells stand out as having an extremely high theoretical energy density yet only modest actual performance. In fact, among common

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9o 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM battery types, nowhere is the discrepancy between the theoretical and actual energy density greater than with aluminum/air cells. Consequently, even small improvements in efficiency would make a large difference in the total energy yield. In current aluminum/air cells, once the anode and electrolyte make contact, the cell must be used immediately since aluminum corrodes so rapidly as to significantly reduce the energy available. This feature currently limits aluminum/air cells to use as sinple-shot reserve OF ~ O . . . . . . . ~ batteries. Reducing corrosion requires modifying the cell electrolyte or the aluminum anode. the polymer-moderated aluminum anode project aims essentially to encapsulate particles of aluminum within an ionic-conducting polymer (polyacrylic acid). In the ideal case, such encapsulation would retard the corrosion reaction and sequester the reaction product during discharge. In preliminary tests, it has been shown to lengthen anode life and maintain electrolyte conductivity, for a more constant discharge potential. Findings and Recommendations. The polymer-moderated aluminum anode research is an interesting and, the committee believes, a unique approach to improving the anode of an aluminum/air battery. The integrity of the polymer encapsulation during the requisite volume expansion of aluminum as it is transformed to aluminum hydroxide by corrosion is a point of concern. The amount of water tied up as aluminum hydroxide will also be a major contributor to the weight of the battery. The proposed ap- proach may be able to minimize this weight penalty through the general reduction of corrosion. Recommendation. Code 353 should evaluate corrosion rates and discharge capacity at low dis- charge rates of the polymer-moderated batteries. Recommendation. Code 353 should continue work on the polymer-moderated aluminum anode and examine the effects of electrolyte water uptake on energy density. Modeling of Power Systems for Marines Modeling of power systems for marines involves the optimization of electrical power systems and loads for future Marine Corps applications. It includes the development of concepts suitable for model- ing the increasingly complex electrical systems of future dismounted soldiers and land vehicles. Model- ing concepts will be explored that are capable of ascertaining the total system consequences of technical advances in various system components, including both power generation and use. As such, the model- ing will be used as a tool for linking decisions on power technology to future operational consequences for Marine Corps forces during expeditionary operations. The approach to optimizing advanced power sources and to understanding the performance of the systems using those sources is the creation of comprehensive and versatile simulation models that can be used to study the total system performance as used in a mission source. In addition, the project has looked at meeting the power needs of the dismounted marine by providing portable battery charging sites and hybrid power sources comprising two or more energy storage or production elements and associated power electronics that control the power demanded from the various energy resources and its distribution to the various loads. Findings and Recommendations. The project on power systems for marines will finish in FY03. This very worthwhile project could have wide applicability across DOD. Historically, the power system designer has had little success in obtaining the load profiles of users in an actual mission. This power modeling project allows for synthesizing of the load profile from a user's equipment package within a mission scenario. The modeling of power systems for marines project then can optimize, for the mission

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BASIC RESEARCH 9 scenario, the power system configuration of a given set of power generation and energy storage compo- nents. Recommendation. Code 353 should continue support of efforts to model power systems for warfighters and make the results available to the other Services. Recommendation. Code 353 should validate the power systems model by collecting power data directly from a marine participating in a simulated mission. Biomechanical Energy Conversion No conventional energy supply is capable of providing the individual marine with continuous and indefinite electrical energy for mobile communications and electronics. Since mobile units lack wired access to generated electricity, they must carry it with them or harvest it from the environment. One possible solution is to use biomechanical energy the energy generated by the movement of the human body. However, such exploitation of biomechanical energy should not place added demands on the human body or alter its biomechanics. The biomechanical energy conversion project proposes to ex- plore biomechanical energy conversion in a systematic and integrative manner. The target will be prototype energy converters that charge conventional energy sources and provide short bursts of energy for communications. The proposed converters would offset some of the mass associated with portable sources of energy such as batteries, capacitors, and fuels. They would complement other possible portable electric power now under investigation so as to become part of a total hybrid energy delivery system. This project will be carried out through a unique collaboration of experts in power electronics and biomechanics. Findings and Recommendations. The biomechanical energy conversion project is a new start, and no results were available. An initial step is an assessment of the energy available from the motion of various body elements (arm, leg, and heel strike). The committee sees potential duplication between this project and one for harvesting electrical energy (described below) since both are conducting kinematic analyses of human motions to determine energy availability. Recommendation. Before proceeding, Code 353 should review the biomechanical energy conver- sion project in light of Marine Corps emergency power and energy requirements as defined in the modeling of power systems for marines project. Recommendation. Code 353 should undertake a careful analysis of the biomechanical energy conversion project and the work on harvesting electrical energy to avoid duplication of efforts in the analysis of human kinematics. Electrical Energy Harvesting The electrical energy harvesting project attempts to steer and exploit developments in polymeric materials for potential use as electromechanical actuators or (in reverse) as generators. Unlike many other actuator/generator materials and devices, polymers could optimize the mechanical coupling with natural human motion. The range of motion over which such polymers generate electricity, together with their elastic resistance, can be tailored to both the displacement and the force of human muscles.

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92 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM The project will evaluate the three most likely points at which energy could be harvested (backpack, heel, and knee) and will measure how important variables (such as compliance of the polymer) affect biomechanics. An optimal design will be developed taking into account ergonomics and power conver- sion efficiency. In parallel, the project will measure human biomechanics to obtain a range of ergonomic solutions and will determine critical parameters affecting energy harvesting and conversion. With both sets of information in hand, an optimal solution will be sought. The project will then test the physiologi- cal and ergonomic effects of the polymer device and establish a quantifiable set of criteria for its evaluation. Findings and Recommendations. The project on electrical energy harvesting is a new start in FY03, and no results were available. The committee notes that DARPA recently conducted similar research on the use of electrostrictive polymers for energy recovery from heel strike. As noted above, the committee also sees potential duplication between this project and the biomechanical energy conversion project since both are conducting kinematic analysis of a person walking to determine energy availability. Recommendation. Code 353 should review the report of the electrical energy harvesting project in order to gain valuable insight on recent developments in this area. Recommendation. Typically, polymeric materials generate very high voltages, so Code 353 should at the same time study the size, weight, and efficiency of the voltage down-converters necessary to convert these materials into systems usable by the warfighter. Recommendation. Code 353 should undertake a careful analysis of the electrical energy harvesting project and the biomechanical energy conversion project to avoid unnecessary duplication of efforts in the analysis of human kinematics. Information Efficiency As the Marine Corps develops the highly mobile and agile force envisioned for EMW, the need to acquire and disseminate large amounts of digital data could overwhelm the warfighter. One of the critical problems from the standpoint of the individual marine is that all energy required to power his or her RF links must be carried. This imposes on the deployed marine a stringent, energy-limited data-rate budget. To ensure that communications systems deliver the right information at the right time to the right people without overly taxing the ability of a marine to carry more batteries, research on informa- tion efficiency has been undertaken in five individual projects. Information Theory for Aim-Point Selection The information theory for aim-point selection project focuses on developing the theory of data fusion based on maximizing information expressly for application to aim-point selection. Another goal of the project is to develop metrics for the loss of target information as the surrounding clutter increases. The expected payoff of the project is a systematic means of sensor design and resource allocation. Findings and Recommendation. Information theory has been used for decades to optimize data fusion. The project on information theory for aim-point selection represents a new application of information theory that can lead to new insights. The project finishes in FY03.

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BASIC RESEARCH 93 Recommendation. Code 353 should closely evaluate the results of the information theory for aim- point selection project before proceeding with future investments in this area. Compression of Digital Elevation Maps Using Nonlinear Wavelets The work on compression of digital elevation maps using nonlinear waveless focuses on developing efficient and flexible compression algorithms for digital terrain elevation data based on nonlinear wavelet algorithms. This project aims to develop algorithms for image compression that allows an end user to query the image at a resolution less than that of the original image. Often, the marine requesting an image does not necessarily need to have the image at the full resolution available from digital terrain elevation data. Image compression would allow users to more easily share map information across bandwidth-limited communication links. Findings and Recommendation. The use of waveless has dramatically reduced the size of various image files. The option of downloading images at less-than-original resolution is a good approach for further reducing the bandwidth necessary for image transport. It is expected that this application will deliver measurable payoffs in terms of map data size and efficiency. This project will finish in FY03. Recommendation. Code 353 should demonstrate the algorithms for image compression with opera- tional Marine Corps units to determine when maps and images at lower than original resolution would be useful to the warfighter. Information Management in a Mobile Environment The objective of the work on information management in a mobile environment is to develop software to assist the rapid analysis of imagery with respect to segmenting images into regions contain- ing various terrain features. For example, if a marine needs a map highlighting wooded areas within an urban setting, a map could be sent that shows only the boundaries of the wooded areas. This segmented map would then improve the efficiency of communicating and sharing information derived from digital imagery over bandwidth-limited links. Findings and Recommendation. Data from digital imagery have the potential to overwhelm the limited communication capacity of a highly mobile military. The combination of wavelet compression (dis- cussed above) and the results of this project can significantly reduce the amount of data that must be distributed throughout the battle space. This project will be complete by the end of FY03. Recommendation. Code 353 should integrate the results of the project on information management in a mobile environment and the project on compression of digital elevation maps using nonlinear waveless as a means of transitioning both to a 6.2 or 6.3 program. Region-Based Image Compression Subject to Energy and Bandwidth Constraints The objective of the region-based image compression project is to investigate how to best generate images in which the resolution of the image can be varied across the field of the image. For example, an image of a farming area may be saved at lower resolution over the farmland and higher resolution over

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94 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM the farmhouses and roads. This project would allow for less data overall to be transmitted to the marine without sacrificing resolution over important areas. Findings and Recommendation. The region-based image compression project utilizes nonlinear wave- lets concentrating on maxima and minima (e.g., of terrain heights and valleys) to organize the com- pressed data in such a fashion that the information not transmitted can be reconstructed later. The project also seems closely coupled to the preceding two efforts in wavelet compression and region segmenta- tion. This was a new start in FY03, so there are still no results. Recommendation. Because the region-based image compression project is at an early state of development, Code 353 should use the results of the two preceding projects to assist in its development. Semantic Source Coding Mobile sensor networks, an important element of future battle space awareness systems, can be large consumers of both energy and bandwidth. Because of the overwhelming amount of information that will be gathered, it will be important to extract, at the source, the essential information content (semantic information) for transmission so as not to overwhelm the communications system. In the semantic source coding project, raw sensor data is processed into information content categories and descriptions, at varying levels of resolution, about battlefield objects and their behavior. Increasing levels of data compression used in the processing are based on waveless, formal languages, and codebooks. Findings and Recommendation. The research on semantic source coding could be useful for under- standing how new and future compression and coding techniques can reduce the demands on communi- cation capacity and energy resources. This project is a new start and should be monitored closely. Recommendation. Code 353 should continue the semantic source coding project through comple- tion, as planned. Sensing As battlefields become more diffuse and the Marine Corps begins to operate more in heavily populated areas, the need arises to more carefully track and monitor the movement of people and equipment. Research in four projects related to sensing addresses the need for systems and materials that will help a marine to identify and track potential threats as well as assist in the monitoring of equipment of interest to potential enemies. Fluorescent Rare-Earth Chelates as Encoded Marking Materials Several rare-earth chelate materials have been found to have tailorable, time-sensitive fluorescence. The principal mechanism for decay is photobleaching of the fluorescence of the rare-earth ion; that is, the material's fluorescence decays in response to light. Thus each new exposure of the top layer of a material to light begins a new "clock" from which to measure the time of exposure. Such a mechanism could then be used to ensure that secured but unguarded areas remain untouched or if touched give time indications for the traffic.

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BASIC RESEARCH 95 Findings and Recommendation. The project on rare-earth chelates is distinguished by having novel aspects and possible future application to Marine Corps needs in area denial. The project is notable for its creative application of new materials and chemical properties. Recommendation. Code 353 should continue the fluorescent rare-earth chelates project as planned and is encouraged to seek out other similar creative and interesting marking system research opportuni- ties. ~ ~ ~ , Atomic Force Microscopy Determination of Radiation Exposure The atomic force microscopy project explores the effects of radiation on materials in order to enable the use of everyday materials for dosimetry. Individual gamma rays contain enough energy to produce microscopic craters on the surfaces of nearby materials. This project aims to employ atomic force microscopy to measure the surface density of these craters and thus the total radiation dose to which the material has been subjected. Findings and Recommendations. The atomic force microscopy project is intriguing in its use of a relatively new technique as a versatile radiation sensor. While the specific method, atomic force micros- copy, may or may not ultimately be employed, the ability to use a diverse set of materials as radiation detectors would improve the ability of the Marine Corps to monitor and track nuclear materials. Recommendation. Code 353 should continue the atomic force microscopy radiation detection project through completion, as planned. Recommendation. Code 353 should initiate studies that search for radiation detection systems that can be more easily transported to and deployed in the field. Recommendation. Code 353 should work closely with DOE laboratories in the development of novel radiation sensing techniques. Surface Enhanced Raman Spectroscopy for Chemical Marker Detection The surface enhanced Raman spectroscopy project is an initial step toward determining the feasibil- ity of using surface enhanced Raman spectroscopy to detect chemical markers. It focuses on finding classes of molecules that could be used in sensors as marker materials to be detected by surface enhanced Raman spectroscopy. Findings and Recommendation. A useful system for chemical sensing requires two components, the chemical to be detected and a method for detecting it. This project is an interesting approach to develop- ing a potentially very sensitive detection method to add to the current inventory of methods. Since this project is a new start, no results are yet available. Recommendation. Code 353 should continue the surface enhanced Raman spectroscopy or chemi- cal marker detection project through completion, as planned.

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96 Microgels for Optical Tagging 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM The microgels for optical tagging project focuses on developing and understanding a materials preparation method for synthesizing micrometer-sized photonic crystals and then depositing them to form bar-code-style optically active tags. One of the goals is to devise a fast and inexpensive method of producing such photonic materials, which would greatly improve their potential utility. Findings and Recommendation. Use of photonic crystal-based optical tags is an interesting and novel approach to the generation of tag materials. The proposed extension of the research to the fabrication of infrared active crystals would also improve the utility of the tags since they could be hidden more easily from normal vision. This project is a new start, and no results are yet available. Recommendation. Code 353 should continue the microgels for optical tagging project through completion, as planned. Human Sensory Enhancement Technology has the potential to increase human awareness and sensitivity to the environment. Research on human sensory enhancement focuses on increasing the warfighter's awareness in a stimu- lus-rich environment, such as an urban setting. Even small improvements in a marine's ability to respond to sensory inputs and react just a few seconds sooner could make a significant difference to a marine's ability to function and survive. Human Perception of Natural Scenes The human perception of natural scenes project is investigating the effects of spatial orientation biases on human perception in the context of realistic visual clutter. Recent work has indicated that the effects on human visual perception of the spatial orientation of dominant image background structure, in the presence of realistic clutter, are very different from what they were thought to be on the basis of previous studies. Findings and Recommendation. The human perception of natural scenes project appears to be studying the response of the human visual system under the influence of a large amount of uniaxial visual clutter (as, for instance, in a forest, where the tree trunks are predominantly aligned in the vertical direction). Understanding the response of the human visual system to uniaxial clutter can be an asset to operational scenario planning, including planning for urban or jungle warfare. It was unclear to the committee, however, how the results of this project would improve the warfighter's capabilities. Recommendation. Code 353 should clarify the design goals of the human perception of natural scenes project in regard to its support of the warfighter. Transition Speech Waveform Features to Enhance Speech Recognition in Noisy Environments The work on transition speech waveform features to enhance speech recognition in noisy environ- ments aims to enhance the efficiency of RF voice communications in a noisy background by isolating

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BASIC RESEARCH 97 and enhancing transitions between speech sounds. It has been found that the transitions between pho- nemes, rather than the quasi-steady-state phonemes themselves, contain most of the intelligible content of speech. Findings and Recommendation. The last four decades have led to a wide array of speech enhancement algorithms, particularly for noisy or bandwidth-limited voice communications systems. This project appears to be appropriately integrated with other academic research in this field and would add to this body of knowledge. Recommendation. Code 353 should examine existing approaches to enhancing speech recognition (under development by other Service laboratories as well as by industry) and test them within the context of the proposed operational scenario before making a significant financial investment in this research on transition speech waveform features. Land Mine Detection Research on land mine detection explores diverse methods of detecting and, possibly, categorizing land mines. Reliable and (especially) rapid detection of mines has proved elusive, and mines have become a major problem both in military combat and for civilians worldwide. In military applications, time is of the essence. Once it has been located, a minefield eventually can be eliminated or a path through it established. However, because of the time it takes to accomplish this, minefields can be effective in keeping military forces from advancing, thereby entrapping forces or, at a minimum, slowing down their advance. As discussed in the 2001 report Naval Mine Warfare4 and indicated in briefings on the MCM thrust,5 the Navy has responsibility for MCM up to the high-water mark, and the Marine Corps is responsible for clearing the beach from the water line to the beach exit points and beyond. The Naval Mine Warfare report also noted that there is no joint Navy/Marine Corps concept of operations that involves Navy and Marine Corps mine-clearing systems in a continuous operation. It was not clear from the presentations to the committee how the 6.2/6.3 MCM core thrust (Chapter 3) is integrated with the 6.1 land mine detection research effort. Consistent with this operational division of mine-clearing responsibilities, the Basic Research projects presented for review all focus on detection challenges associated with buried land mines. There is no application of S&T to MCM as an end-to-end problem (i.e., from the sea to inland) that spans the four Services. Recommendation. Code 353 should construct an overview table that compares all the different methods for mine detection from dog sniffing to nuclear resonance and should then extend the table to evaluate combinations of techniques. 4Naval Studies Board, National Research Council. 2001. Naval Mine Warfare: Operational and Technical Challenges for Naval Forces, National Academy Press, Washington, D.C., p. 101. 5David C. Heberlein, Institute for Defense Analyses, Technical Advisor, Expeditionary Warfare Operations Technology Division, Office of Naval Research, "ONR Code 353 Naval Science Board Review, Mine Countermeasures (MCM) Thrust," slide 3, presentation to the committee on May 14, 2003.

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98 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM Recommendation. Code 353 should coordinate mine countermeasures research strongly with Army land mine detection efforts. Recommendation. Code 353 should support and leverage Navy mine countermeasures programs that show promise for use in the shallow water and surf zone environment. Recommendation. Code 353 should establish 6.1 companion projects to the Core Thrust MCM projects to include algorithm development not only for new sensors but also for fused combinations of sensors (co-located or remote) in order to increase detection capability (mainly signal-to-clutter) over a broad range of environmental and operational conditions. This very serious problem needs good ideas more than it needs money. The five seismic and acoustic mine detection projects listed below include an innovative combina- tion of two technologies for mechanical excitation of buried mine vibration seismic and acoustic- with RF detection of the effects at the ground surface of the mine's vibration. As the waves from the buried vibration propagate to the surface, ground height changes (ripples) are measured by RF methods. Any underground obstruction leads to wave scattering and/or interference. Like purely RF methods (e.g., ground-penetrating radar), this technique could involve high false alarm rates due to buried objects like rocks, holes, subsurface water, or other underground clutter. The general approach common to all seismic, acoustic, and RF methods is to determine the signature of particular mines and eliminate all other signatures. It appears to the committee that this is a very precarious method of separating a mine (and only a particular mine) from clutter. Environmental Issues in Seismic Mine Detection The environmental issues studied in connection with seismic mine detection are related to the propagation of ground surface waves in a full spectrum of representative soil types and conditions for detecting buried objects. Field testing is nearly complete, and there are no stated plans to continue the effort. Findings and Recommendation. The environmental issues in seismic mine detection project was char- acterized as essentially complete, with the project having met its objective of providing a theoretical basis for modeling the resonant response of mines in a wide variety of soil types. There were no transition roadmaps or discussion of any follow-on activity to use the results. Recommendation. Code 353 should terminate the environmental issues in seismic mine detection project as scheduled and use the results to investigate the potential of seismic methods in the saturated environment near the surf zone. False Indicators in Acoustic/Seismic Land Mine Detection The project on false indicators in acoustic/seismic land mine detection is a new start. It is being established with the objective of understanding the mechanisms responsible for false alarms in acoustic and seismic land mine detection. It will investigate the effects of soil properties and of nonlinear coupling as a function of excitation frequency and spatial resolution.

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BASIC RESEARCH 99 Findings and Recommendations. The project on false indicators is currently focusec} on buried lane} mines in the beach zone above the high water mark ant} beyond. Recommendation. Code 353 should continue with initiation of the false indicators in acoustic/ seismic lane! mine detection project ant! should ensure that it is closely coorclinatec! with the seismic ant! the acoustic buried lane} mine detection projects. Recommendation. Code 353 should consider broadening the false indicators in acoustic/seismic lane! mine detection to include the craft lancling zone, the surf zone, and very shallow water environ- ments. Seismic Detection of Buried Land Mines This project is a new start to investigate the interaction between the soil and mine seismic energy situations where the acoustic wave is tuned to generate a resonant vibration mocle within the buried mine. The seismic surface wave is generated at some horizontal distance from the buried mine on the ground surface. The project will investigate the projection of mine vibration mocles up to the ground surface, where they can be cletectec} by an acoustic or electromagnetic (inclucling optical) sensor above the buried mine. Findings and Recommendation. Seismic detection of buried lane! mines is an extremely challenging research topic, and the committee is concerned that soil packing density ant! mine orientation could leac! to significant underreporting of mines. This project currently focuses on buried lane! mines in the beach zone above the high-water mark ant} beyond. There is a potential for leverage with the project clescribec} below, which is investigating the acoustic detection of buried mines. Recommendation. Code 353 should ensure that the seismic detection of buried lane! mines project collaborates closely with the acoustic detection of lane! mines project, since the two projects involve . . . . . Slml. tar mine ant SOT. . lSSUeS. Acoustic Detection of Buried Land Mines This project is a new start that aims to quantify key parameters ant! performance thresholds for the resonant acoustic detection of buried lane! mines. It will investigate energy propagation ant! resonance measurements (with and without an air gap between the acoustic source and the receiver vertically above the buried mine) to quantify the upper frequency limits to resonant acoustic lane} mine cletection. Findings and Recommendation. Acoustic detection of buried lane} mines is an extremely challenging research topic, and the committee is concerned that soil packing density ant! mine orientation could leac! to significant underreporting of mines. This project is currently focusec! on lane! mines buried in the beach zone above the high-water mark ant! beyond. There is a potential for leverage with the project investigating the seismic detection of buried mines. Recommendation. Code 353 should ensure that the acoustic detection of buried lane} mines project collaborates closely with the seismic detection of buried lane! mines project, since the two projects involve similar mine ant! soil issues.

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100 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM Impulse or Ultrawideband Radar Research The objective of the impulse or ultrawideband radar research project is to examine buried-target scattering of UWB electromagnetic radiation (as in impulse radar) by computer analysis (signal process- ing techniques) to identify the target (a buried mine). Findings and Recommendation. Research on ultrawideband radar for mine detection is a collaborative effort among ONR, ARL, and the Swedish Defence Research Agency (FOI). Variations on this technol- ogy are also being investigated by the Army NVESD for application in its Ground Standoff Mine Detection System program, which is scheduled to transition to a system development and demonstration program in 2004 and may already be addressing Marine Corps land-based countermine problems. Recommendation. Code 353 should establish a relationship with NVESD to leverage information on both phenomenology and implementation for ultrawideband radar systems applicable to mine detec- tion. ~ An, Laser Eye Protection While such weapons are outlawed by international convention, the possibility exists for countries or terrorist groups to develop laser weapons intended to blind attacking troops. Such weapons would pose a particular threat to the Marine Corps because of its mission as a first-responder force, so that Marine Corps units would likely be among the first to encounter such a new and asymmetric threat. For this reason a small project has been started to develop eye protection systems that would defeat weapons meant to blind. Like mine detection, laser eye protection has been studied for decades, is technically extremely challenging, and is in need of good ideas more than it needs money. This project appears to be a good idea. Nanostructured Optical Limiters Organic polymer multilayers in nanometer thicknesses are being prepared that could counter anti- personnel lasers and future frequency-agile versions of these threats. Dielectric multilayers with alter- nating high and low refractive indexes act as interference filters; the wavelength filtered is determined by the thickness of the layers, and the maximum attenuation is a function of the number of layers. Findings and Recommendations. Nonlinear optical properties and novel materials preparation methods are being used to create nanostructured multilayered materials for further study. This is a novel approach that promises great design flexibility. In general, a uniform multilayer structure will only work against a particular laser frequency. A major problem is to achieve a multilaYer filter that w. ill function against tw. o or more w. avelencths or be _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ ~ _ _ O .. . . . ~ . . .. Be. . . . . - . . . . .. - tunanle against a broach range of laser wavelengths. -l-ne approach being stucllecl IS clescrlnecl as enabling fabrication of up to ~10,000 layers, presumably with controllable thicknesses, which suggests the potential for creating graded or multiply-tuned and broadband structures. The committee is aware of similar work once supported by the Army NVESD but does not know where this work stands now. The work on nanostructured optical limiters is well motivated both scientifically and for its potential implications for the Marine Corps. The methods and techniques being developed have a number of other possible applications. This research is a good example of basic science with a clear practical objective.

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BASIC RESEARCH 10 Recommendation. Code 353 should proceed with the nanostructured optical limiters project through completion, as planned. Recommendation. Code 353 should ensure that further efforts in laser eye protection build on similar Army efforts. Energetic Materials Two projects involving energetic materials were active in FY03. Existing concerns about lethality- to-weight ratio and safety, both of which call for energetic materials with higher energy density and reduced sensitivity, are magnified by the demands of sea basing and expeditionary warfare. The two projects described address (1) gaining a fundamental understanding of sensitization and initiation and (2) understanding how to develop new binders for explosives and propellants. Understanding and Predicting Explosive Response of Metal-Metal and Metal-Oxidizer Compositions Subjected to Shock or Impact Theoretical and atomic force microscopy studies of metal-metal and metal-oxidizer energetics from the Indian Head Division of the Naval Surface Warfare Center were described to the committee. This research seeks to understand the processes responsible for initiation of chemical reactions as a result of shock or impact loading and to use this fundamental understanding to develop both safer and ultimately more lethal explosives. It has succeeded in identifying shear bands as likely sources of initiation following shock or impact and suggests common features for initiation due to impact or shock in different forms of crystalline explosives. Recognizing that explosive sensitivity to mechanical or thermal abuse is well characterized, the research focuses on understanding plastic deformation and energy dissipation at the atomic level. The long-term goal is to predict the initiation behavior of representative metal-metal or metal-oxidizer compositions, to compare the predictions with experimental data, and ultimately to predict and optimize the behavior of new explosive compositions. Findings and Recommendations. The study of blast initiation in the context of safety has clear connec- tions to the logistical challenges of sea basing and EMW. This project on understanding explosive response has produced initial results of interest and has identified areas for further study. The good balance of theoretical/modeling work and small-scale experimentation positions this effort well for further evaluation and application. The program is well focused, productive, and of unique long-term interest to the Marine Corps. The committee recognizes the challenges posed by the need to coordinate further development activities with other organizations that play leading roles in the development and delivery of ammuni- tion for the joint Services. Recommendation. Code 353 should proceed with the work on predicting explosive response through completion, as planned. Recommendation. Code 353 should ensure that energetic materials research remains part of the MCS&T program's Basic Research effort.

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102 2003 ASSESSMENT OF ONR'S MARINE CORPS SCIENCE AND TECHNOLOGY PROGRAM Synthesis of 1,2,3,-Triazoles via 1,3-Dipolar Cycloaddition of Organic Azides with Activated Acetylenes planned. New energetic ingredients being studied for higher-performance explosives and propellants can be incompatible with the cure reaction of the urethanes now used as binder materials. This project ad- dresses designs for a new propellant and binder system based on the 1,3-dipolar cycloaddition reactions of acetylenes and azides to form triazole rings. The goal is binders that are cure-compatible with higher- energy ingredients, facilitating lighter-weight warheads. The approach involves modeling, establish- ment of structure-property relationships, and fabrication and characterization of small propellant sys- tems. The project addresses the basic questions of manufacturing incompatibility that have prevented the introduction of higher-density explosives. Results to date show that the triazole cure works well, evolves no water or gaseous by-products, and proceeds in the presence of energetic compounds. The problems facing continued development of this technology center on a clear understanding of the structure- property relationships and on the cross-linking polymerization chemistry. Findings and Recommendations. The development of energetic materials with an improved lethality- to-weight ratio has a clear connection to the logistical challenges of sea basing and EMW. This project has produced initial results of interest and has identified areas for further study. The good balance of theoretical/modeling work and small-scale experimentation positions this effort well for further evalua- tion and application. Recommendation. Code 353 should proceed with the novel binder project through completion, as Recommendation. Code 353 should ensure that energetic materials research remains part of its Basic Research effort.