The present thesis analyses and clarifies the phenomenon of hybrid warfare. While the term has established its place in the political lexicon, current definitions and explanations are inadequate and unhelpful. This thesis addresses that shortfall by providing a concise strategic definition and a unifying theory of hybrid warfare. As a thesis grounded in the Realist tradition, the analysis focuses on the strategic implications with a view to aid in practical policy-making. Following a theoretical examination of the context and the intellectual history of the term, hybrid warfare is defined as a deliberately opaque blend of conventional and unconventional warfare. The rules of the international order and its 'guardian powers' are a key to understanding hybrid warfare and this thesis provides that understanding through the concept of the quinity. Based on the trinity, a concept emanating from Clausewitzian thought, the quinity blends traditional notions of war with the contemporary international order. The unique set of circumstances which such a combination creates is then combined with the proposed definition and operationalised through an examination of the defence policies and doctrines of the leading global powers. Hybrid warfare, whether practiced by state-like actors like Hezbollah, or states like Russia and China, can be said to represent the future of warfare, at least in the near- to mid- term. As a form of warfare which is not limited to any one domain, hybrid warfare is examined in its land, air, and maritime iterations by analysing the cases of the 2006 Lebanon War, the 2014 Ukraine crisis, and the South China Sea disputes. Its combination of opaqueness, effectiveness, impact, and strategic surprise makes it a carefully balanced and finely calibrated tool of international coercion.

Quantification of flood risk and flood inundation requires accurate numerical simulations, both in terms of the mathematical theory that underpins the methods used and the manner in which the meteorological phenomena that cause flooding are coupled to such systems. Through our research, we have demonstrated how rainfall and infiltration effects can be incorporated into existing flood models in a rigorous and mathematically consistent manner; this approach departs from preceding methods, which neglect terms representing such phenomena in the conservation or balancing of momentum. We demonstrate how the omission of these terms means the solution derived from such models cannot a priori be assumed to be the correct one, which is in contrast to solutions from the extended system we have developed which respect the energetic consistency of the problem. The second issue we address is determining how we can model these meteorological phenomena that lead to flooding, with a specific interest in how existing observation data from rain gauges can be incorporated into our modelling approach. To capture the random nature of the precipitation, we use stochastic processes to model the complex meteorological interactions, and demonstrate how an accurate representation of the precipitation can be built. Given the specific industrial applications we have mind in regards to flood modelling and prediction, there will be a high computational cost associated with any such simulations, and so we consider techniques which can be used to reduce the computational cost whilst maintaining the accuracy of our solutions. Having such an accurate flood model, coupled with a stochastic weather model designed for efficient computational modelling, will enable us to make useful predictions on how future climate change and weather patterns will impact flood risk and flood damage.

This thesis examines how global environmental crisis narratives and discourses have influenced environmental policy and practice in conservation programmes for the Okavango Delta, Botswana. In particular, it highlights the contested nature of biodiversity conservation and the embedded power relations in the framing, definition and crafting of solutions to the problem of biodiversity degradation at local, national and international levels. The thesis therefore examines, based on these framings, the consequences of global environmental agreements, such as the Ramsar Convention and the UN Convention on Biological Diversity, for local livelihoods in terms of access to and control over local environmental resources in the Okavango Delta. Using a political ecological conceptual lens and related literature on common pool resource management and community-based natural resource management, this thesis traces the changing perceptions, narratives and discourses relating to the Okavango Delta over time, and assesses how these have shaped changes in policy for the Delta's use and management. It specifically analyses the implementation of international programmes and their role in facilitating these changes. Through an in-depth study of dynamic human-environment interactions around fisheries and other wetland resources, this thesis shows how international interventions have not only increased conflicts but also facilitated the strict regulation of these resources. The thesis therefore analyses how framing these and other common pool resources as being of ‘international significance' alters control over them and affects the livelihood security of the local people that depend on these resources. It concludes that such restrictive conservation policies and management approaches have led to a transfer of control over wetland resources from local subsistence users to other, more powerful, commercial interests, especially those in the international tourism industry.

nÃo hà / A modelagem ambiental à uma importante ferramenta para projetos e estudos envolvendo a gestÃo ambiental, devido à complexidade dos sistemas ambientais. Com ela à possÃvel integrar um grande nÃmero de variÃveis e processos de forma a obter uma visÃo dinÃmica de tais sistemas e avaliar as suas condiÃÃes presentes e futuras. Neste trabalho sÃo apresentados os resultados de modelagens da qualidade bacteriolÃgica da Ãgua da Ãrea costeira de Fortaleza (Brasil), frente a diversas entradas de cargas contaminantes nas mesmas. Coliformes termotolerantes, usados como indicadores de qualidade de Ãguas de banho pelas normas brasileiras, foram numericamente modelados usando o SisBaHiA (Sistema Base de HidrodinÃmica Ambiental), usando-se cargas contaminantes provenientes de trÃs diferentes tipos de fontes: rios, galerias pluviais e emissÃrio submarino. Os modelos foram implementados de forma a representar as variaÃÃes de decaimento frente à radiaÃÃo solar e outros fatores ambientais. Foram obtidos valores relativamente prÃximos entre os resultados modelados e monitorados em campo em diferentes cenÃrios. Os resultados mostraram que as galerias pluviais sÃo as fontes de contaminaÃÃo mais importantes, respondendo por episÃdios de nÃo cumprimento dos padrÃes de qualidade de Ãgua de banho, especialmente durante os perÃodos chuvosos. AlÃm disto, os resultados mostraram nÃo haver riscos da pluma do emissÃrio submarino de Fortaleza alcanÃar as Ãreas de banho das praias da cidade. / The environmental modeling is an important tool for studies and projects involving environmental management, due to the complexity of environmental systems. With it you can integrate a large number of variables and processes in order to obtain a dynamic view of such systems and assess their present and future conditions. This paper presents the results of modeling the bacteriological quality of the water in the coastal area of ​​Fortaleza (Brazil), and against several entries contaminant loads in them. Fecal coliform, used as indicators of quality of bathing waters by Brazilian standards, were numerically modeled using SisBaHiA (System Base Environmental Hydrodynamics), using contaminant loads from three different sources: rivers, storm sewer and outfall . The models were implemented to represent the changes in decay forward to solar radiation and other environmental factors. Values ​​were relatively close results between modeled and monitored in the field in different scenarios. The results showed that the storm sewers are the most important sources of pollution, accounting for episodes of non-compliance with water quality standards for bathing, especially during rainy periods. Moreover, the results showed no risk of the outfall plume reaching Fortaleza bath areas the city beaches. .

Neste trabalho, propõe-se o desenvolvimento de procedimento analítico automático para determinação espectrofotométrica de microcistinas em águas empregando o processo de multicomutação em fluxo. O módulo de análise para implementar o procedimento analítico empregou um bomba de seringa para propulsão de fluído e válvulas solenóide para controlar a amostragem. A bomba de seringa foi construída no laboratório de Química Analítica, CENA/USP, onde foi empregado um motor de passo para fazer o deslocamento do êmbolo da seringa. Como detectores foram empregados, um fotômetro da Oriel Instrument e um fotômetro desenvolvido no laboratório de Química Analítica, CENA/USP, baseado em um fotodiodo da BURR-BRAWN e projetado para este procedimento. Uma cela de fluxo com caminho óptico de 40 mm e volume interno de 32 \'mü\'L, foi construída sob medida para permitir fácil acoplamento da fonte de radiação (LED) e dos fotodetectores, formando uma unidade compacta. O controle do sistema de fluxo, incluindo o motor de passo, foi executado por um microcomputador usando um software escrito em linguagem Quick Basic 4.5. Os sinais gerados pelos fotômetros em diferença de potencial eram convertidos para digital por um multímetro e enviados para o computador através da interface serial 232. O sistema proposto foi empregado para determinação de microcistinas em águas de rios e lagoas. A exatidão foi averiguada comparando com os dados obtidos empregando um equipamento ELISA. A faixa de concentração situada entre (0,1 e 0,8 \'mü\'gL-1) de microcistina indica que o sistema proposto pode ser usado em serviços de tratamento de águas onde o requerimento da ANVISA (Portaria n°518, 2004) deve ser alcançado / In this work, it was proposed the development of an automated analytical procedure based on multicommutation for the photometric determination of microcystins water. The flow module to implement the analytical procedure employed a syringe pump for solution propelling and solenoid valves for sampling control. The syringe pump was constructed in the laboratory CENA/USP, employed a step-motor to carry out the displacement of the syringe piston. As photodetectors was employed an Oriel Instrument photometer and a photometer developed in the laboratory CENA/USP based on a BURR-BRAWN photodiode and designed to be used in this procedure. A flow cell with optical pathlength of 40 mm and inner volume of 32 \'mü\'L was tailored to allow easily coupling of radiation source (LED) and photodetector, forming a compact unit. The control of the flow system, including the step-motor was performed by a microcomputer using a software wrote in Quick BASIC 4.5. The signals generated by the photometers in difference of potential were converted to digital by a digital multimeter and sent to the microcomputer through the serial interface 232. The proposed system was employed for the photometric determination of microcystins in water. Accuracy was assessed comparing the results with those obtained using a ELISA instrument. The concentration response (0,1 e 0,8 \'mü\'gL-1 microcystins) and limit of detection lower than 0.01 \'mü\'gL-1 microcystins, indicated that the proposed system can be used in plants of water treatment where the ANVISA requirement must be maintained

Este trabalho teve por objetivos estudar a distribuição das concentrações de atividade dos isótopos de rádio de meias-vidas longas, 226Ra e 228Ra, em amostras de águas minerais coletadas no Balneário de Caxambu (MG) e no Balneário de Águas de Lindóia (SP). Foram observadas concentrações de atividade de 228Ra relativamente aumentadas em relação às de 226Ra nas águas minerais estudadas no Balneário de Caxambu. As concentrações elevadas de carbonatos e bicarbonatos destas águas podem resultar em um conseqüente aumento da solubilidade dos isótopos de Ra e pode ter um papel importante para a distribuição do 228Ra e para as reações de equilíbrio entre as fases sólida e líquida das soluções. No Balneário de Caxambu, as concentrações de atividade médias aritméticas variaram de 83 mBq L-1 a 3599 mBq L-1 e de 60 mBq L-1 a 4481 mBq L-1 para 226Ra e 228Ra, respectivamente. O maior valor de atividade de 226Ra foi observado nas águas da Fonte Venâncio, enquanto que a concentração máxima de 228Ra foi determinada na Fonte Ernestina Guedes. As razões de atividade 228Ra/ 226Ra variaram de 0,079 (Fonte Conde DEau e Princesa Isabel) a 4,2 (Fonte Mairink II). Em Águas de Lindóia as concentrações de atividade médias aritméticas variaram de 4,6 mBq L-1 a 41 mBq L-1 e de 30 mBq L-1 a 54 mBq L-1 para 226Ra e 228Ra, respectivamente. O maior valor de atividade de 226Ra foi observado nas águas da Fonte Engarrafada São Jorge, enquanto que a concentração máxima de 228Ra foi determinada na Fonte Santa Filomena (torneira pública 2). As razões de atividade 228Ra/ 226Ra variaram de 1,2 (Fonte Engarrafada São Jorge) a 9,1 (Fonte Engarrafada Jatobá 1). A exposição de indivíduos do público à radiação natural em virtude do consumo das águas minerais também foi avaliada neste trabalho. As doses efetivas foram estimadas utilizando-se um modelo dosimétrico conservativo, e integrando-se os resultados ao longo de 70 anos de vida de um indivíduo adulto, após a incorporação de 226Ra e 228Ra. Os resultados desta avaliação radiossanitária demonstraram que o nível de referência de dose efetiva comprometida recomendado pela Organização Mundial de Saúde de 0,1 mSv a-1 foi ultrapassado em quase todas as fontes de Caxambu, exceto para a Fonte Viotti, Fonte Dom Pedro e Fonte Dona Leopoldina. Em Águas de Lindóia e Lindóia as maiores doses efetivas comprometidas obtidas foram 8,4 10-3 mSv a-1 para o 226Ra (Fonte engarrafada São Jorge) e 2,6 10-2 mSv a-1 para o 228Ra (Fonte Santa Filomena torneira pública 2). Estes valores são menores que o limite recomendado pela Organização Mundial de Saúde. Doses efetivas comprometidas de até 7,4 x 10-1 mSv a-1 para o 226Ra (Fonte Venâncio, Caxambu) e 2,2 mSv a-1 para o 228Ra (Fonte Ernestina Guedes, Caxambu) foram estimadas no presente trabalho. No caso do 226Ra, este valor representa menos que 31% da dose efetiva média anual atribuída a radioatividade natural. Contudo, no caso do 228Ra, o limite anual de dose efetiva comprometida recomendado pela ICRP (considerando-se todas as fontes de exposição da população mundial à radiação) foi excedido não só na Fonte Ernestina Guedes, mas também na Fonte Beleza. / The aim of this work was to study the long-lived Ra isotopes, 226Ra and 228Ra, natural distribution in mineral and spring waters from Caxambu (MG) and Águas de Lindóia (SP) waterparks. In Caxambu mineral waters it was observed 228Ra acitivity concentrations slightly higher than those of 226Ra. The elevated content of carbonates and bicarbonates of these waters can result in an increased solubility of the both Ra isotopes and may play an important role for the fate of 228Ra and its equilibrium distribution between solid and liquid phases. In Caxambu Thermal Spa, arithmetic mean activities ranged from 83 mBq L-1 to 3599 mBq L-1 and from 60 mBq L-1 to 4481 mBq L-1 for 226Ra and 228Ra, respectively. The highest 226Ra activity was found in Venancio Spring, while the maximum 228Ra activity value was determined in Ernestina Guedes. 228Ra/ 226Ra activity ratios varied from 0.079 (Conde DEau and Princesa Isabel Spring) to 4.2 (Mairink II Spring). In Águas de Lindóia, arithmetic mean activities ranged from 4.6 mBq L-1 to 41 mBq L-1 and from 30 mBq L-1 to 54 mBq L-1 for 226Ra and 228Ra, respectively. The maximum 226Ra activity concentration was found in the bottled mineral water São Jorge, while the higher 228Ra activity concentration was determined in Santa Filomena Spring (public station 2). 228Ra/ 226Ra activity ratios varied from 1.2 (bottled mineral water São Jorge) to 9.1 (bottled mineral water Jatobá 1). This work also performed the dose assessment due to the ingestion of 226Ra and 228Ra in Caxambu and Águas de Lindóia mineral and spring waters. The committed effective doses were estimated by using a conservative dosimetric model and taking into account the results over a lifetime (70 years) following intake of both long-lived Ra isotopes. The results from this radiological evaluation showed that the guindance committed effective dose level of 0.1 mSv y-1 recommended by World Health Organization was exceeded in almost all samples studied in Caxambu, except for Viotti Spring, Dom Pedro Spring and Dona Leopoldina Spring. In Águas de Lindóia and Lindóia, the highest committed effective doses estimated were 8.4 10-3 mSv y-1 for the intake of 226Ra (bottled mineral water São Jorge) and 2.6 10-2 mSv y-1 for 226Ra (Santa Filomena spring station 2). Both values are below the limit recommended by World Health Organization. The maximum commited effective doses per year obtained in this work were 7.4 10-1 mSv y-1 for 226Ra (Venancio Spring) and 2.2 mSv y-1 for 228Ra (Ernestina Guedes Spring). Considering the case of 226Ra intake via mineral water, the dose obtained represents less than 31 % of the average effective dose attributable annually from natural background radiation. However, in the case of 228Ra the annual committed effective dose limit recommended by ICRP (considering all sources of radiation exposure for the world population) was exceeded not only in Ernestina Guedes Spring, but also in Beleza Spring.

Neste trabalho foi realizado um estudo estatístico do desempenho analítico das técnicas eletroquímicas Voltametria de pulso diferencial (VPD), Voltametria de onda quadrada (VOQ) e Voltametria de múltiplas ondas quadradas (VMOQ) para a redução do herbicida paraquat em ultramicroeletrodo de ouro (UME-Au) e sua análise e quantificação em águas puras e naturais. Os estudos da redução eletroquímica do paraquat foram realizados em eletrólito de suporte Na2SO4 0,1 mol L-1 em pH = 5,5. Os resultados mostraram a presença de dois picos de redução bem definidos , com o pico 1 em -0,64 V e o pico 2 em -0,94 V vs Ag/AgCl 3,0 mol L-1. Para as análises foi utilizado o pico 1 que é referente a uma reação em solução, onde a superfície eletródica serve apenas como intermediadora na transferência eletrônica. Utilizando-se os parâmetros experimentais e voltamétricos otimizados, curvas de trabalho foram construídas em eletrólito de suporte preparado com água ultrapurificada. Para a VPD, VOQ e VMOQ, os limites de detecção encontrados utilizando-se o método descrito em Miller & Miller e considerando-se o pico 1 foram: 55,35 ± 0,18 µg L-1 , 37,50 ± 0,32 µg L-1 e 21,42 ± 0,51 µg L-1, respectivamente. A metodologia foi aplicada em amostras de águas coletadas no Rio Mogi-Guaçu na cidade de São Carlos-SP. A variação da inclinação das curvas de trabalho obtida nas análises destas amostras foi praticamente insignificante em relação àquela obtida utilizando-se o eletrólito de suporte preparado com água ultrapurificada para as três técnicas utilizadas, mostrando pouca interferência da matéria orgânica presente nas amostras de águas naturais. Os menores valores de concentração mensuráveis de paraquat nas amostras de águas naturais foram inferiores ao valor máximo de resíduos permitido pela legislação brasileira para águas residuárias (100 µg L-1), mostrando a viabilidade na aplicação da metodologia proposta. Os cálculos dos limites de detecção e quantificação, a avaliação dos erros experimentais e os limites de confiança foram realizados a partir do procedimento estatístico descrito em Miller & Miller. Os valores de limites de detecção encontrados apresentam um significado físico e realístico para esta grandeza, já que foram determinados por interpolação nas curvas analíticas, construídas a partir da relação entre as concentrações do pesticida e os sinais obtidos. Estes mesmos limites foram calculados utilizando-se o método recomendado pela IUPAC e os valores encontrados foram 29,43 µg L-1 para VPD, 3,63 µg L-1 para VOQ e 0,37 µg L-1 para VMOQ. Estes resultados mostram diferenças de até 2 ordens de grandeza de uma técnica para outra, que se não forem bem avaliados podem levar o analista a conclusões equivocadas. / Statisctic studies of the analytical performance of Differential pulse voltammetry (DPV), Square wave voltammetry (SWV) and Multiple square wave voltammetry (MSWV) electrochemical techniques was performed for the electrochemical reduction of the paraquat herbicide on an gold ultramicroelectrode (Au-UME), aiming its analysis and quantification in pure and natural waters. The electrochemical reduction of paraquat was studied in 0.1 mol L-1 Na2SO4 support electrolyte in pH = 5.5 . The electrochemical responses showed two well-defined reduction peaks with potentials of -0.64 and -0.94 V vs Ag/AgCl 3.0 mol L-1 for peaks 1 and 2, respectively. The mathematical treatment was performed with data from peak 1, which is associated with a reversible solution reaction, where the electrode surface acts only as the electron transfer mediator. Working curves were obtained using the optimized experimental parameters in support electrolyte prepared with high purity water. To DPV, SWV and MSWV, the detection limits found for the peak currents associated to peak 1 were: 55.35 ± 0.18 µg L-1, 37.50 ± 0.32 µg L-1 and 21.42 ± 0.51 µg L-1, respectively. An analogous analytical procedure was applied in water samples collected in Mogi-Guaçu River, in São Carlos County, state of São Paulo. The variation in slope values, between curves obtained from pure water and those from river waters were practically depreciable for the three analytical methods, showing that the organic components and others contaminants present in natural waters caused only a minor interference in the measurements. The lower measurable values for paraquat in water samples were smaller than the allowed maximum of residue established by the Brazilian legislation for waste waters (100 µg L-1), indicating the developed methodology as convenient to such application. Calculations of detection and quantification limits, the evaluation of experimental errors and the limits of confidence were performed by the statistical procedure reported by Miller & Miller. The obtained detection limits values present a true physical significance, in a realistic order of magnitude, as they were determined by interpolation of the experimental analytical curves. The same analytical curves were submitted to the IUPAC methodology yielding the values of 29.43, 3.63 and 0.37 µg L-1 para DPV, SWV and MSWV, respectively, for pure water measurements. These results showed a difference up to two orders of magnitude from those obtained by the statistical methodology and may promote false conclusions, if not properly evaluated.

This dissertation combines laboratory experiments and analysis of field samples to examine tungsten (W) geochemistry. Data from low ionic strength experimental solutions at room temperature containing between 0.01 M to 0.0002 M total sulfide and 0.0027 M - 0.0001 M tungstate were analyzed using UV/VIS spectrophotometry. Stability constants have been determined for the formation of mono-thiotungstate log K01= 3.43 ± 0.61, di-thiotungstate log K12 = 3.02 ± 0.61, tri-thiotungstate log K23 = 2.82 ± 0.02, and we estimated the tetra-thiotungstate log K34 ~ 2.34. Analysis of W, Mo, Mn, and Fe concentrations in estuarine surface and pore waters and sediments captured environmental samples from oxic and sulfidic conditions. Both surface waters and sediments demonstrated a positive correlation between W and Fe. Unlike Mo, which was depleted in sulfidic salt marsh pore waters, W was enriched in all pore waters in comparison to overlying waters. Thermodynamic modeling of W and Mo thioanion species in sulfidic pore water samples predicts ≤ 50% of tungstate (WO42-) forms thiotungstate species and complete conversion of molybdate (MoO42-) to tetrathiomolybdate (MoS42-). Unlike tetrathiomolydate that is known to be more particle reactive than molybdate, increases in dissolved W coincide with increases in dissolved sulfide in pore waters, suggesting thiotungstates are less particle reactive than thiomolybdates at circum-neutral pH. Finally, sediment analysis suggests sequestration of W is dependent on surface water salinity in the intermediate marsh sediments, and long-term W entrapment occurs in sulfidic salt marsh sediments. / acase@tulane.edu

Coarse particulate organic matter (CPOM) is an essential part of the food chain in aquatic ecosystems because it represents a readily available carbon and energy source. The process by which it decomposes in rivers has been well studied and documented. However, the rate and extent of biodegradability of various CPOM components (i.e., twigs, leaves, grass, etc.) in storm drains is not well understood. The Jordan River TMDL study identified storm water generated CPOM as a likely cause of low dissolved oxygen levels in the lower Jordan River, but recent investigations have suggested that dissolved organic matter generated from this CPOM in storm drains and culverts entering into the Jordan River, rather than the CPOM itself, is the main driver of oxygen impairment. The degradability of CPOM components transported and stored in the storm drain system was studied to understand its relative impact on dissolved oxygen and nutrient status in the Jordan River. Results indicate the generation of highly degradable organic material is a function of the starting CPOM, and oxygen consumption is associated with the dissolved portion of organic material leached from CPOM in water. Leaves and grass produced the highest levels of all parameters studied. Between 93% to 95% of total oxygen demand is generated within the first 1 to 3 hours of the 24 hour test. Chemical oxygen demand and dissolved organic carbon proved to be the best indicator of biochemical oxygen demand. By using the results of the leaching study an estimate of water quality indicator levels in the Jordan River was made, and was compared to levels in samples collected from the Jordan River. The estimate proved accurate for dissolved organic carbon but not for total or volatile suspended solids. Results of this study were used to discuss possible solutions to reduce oxygen demand in the Jordan River.

The widespread use of laser line scanners (LLS) aboard unmanned underwater vehicles in the last decade has opened a unique window to a series of ecological and military applications. Variability of underwater light fields and complexity of light contributions reaching the receiver pose a challenge for target detection of LLS under different environmental conditions. The interference of photons not originating at the target (e.g. water path, bottom) can often be minimized (e.g., time-gated systems) but not excluded. Radiative transfer models were developed to better discriminate noise components from signal contributions at the receiver for two continuous LLS: Real-time Ocean Bottom Optical Topographer (ROBOT) and Fluorescence Imaging Laser Line Scanner (FILLS). Numerical experiments using forward Monte Carlo methods were designed to explore the effects of diverse water turbidities and bottom reflectances on ROBOT and FILLS measurements. Interference due to solar light on LLS target detection was also examined. Reliability of radiative transfer models was tested against standard models (Hydrolight) and aquarium measurements. In general a green laser was the best all around choice to detect targets using both LLS sensors. Based on signal-to-noise (S/N) values, performance of ROBOT for target detection was greater (two-fold) than FILLS because of the lower contribution of path photons in ROBOT than FILLS. When ROBOT was located at 1 m above the target, path radiance contributions (noise) were reduced up to 25-fold in clear waters (0.3 mg m-3) with respect to turbid waters (5 mg m-3). Since ROBOT was more discriminative of bottom reflectance discontinuities (high-contrast transitions) than FILLS, algorithms are proposed to retrieve contrasting man-made targets such mines.