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The coastal aquifer of the Essaouira syncline (Morocco) was studied to identify the main processes at the origin of the salinization of groundwater. In fact, a multicriteria analysis approach on hydrochemical data and physicochemical parameters of the Plio-Pleistocene aquifer was used to understand their spatio-temporal variation and their origins. Currently, integrated water resource management has become paramount to both local, regional, national, and international. This management is favored by extreme hydrological events (droughts or floods) which can have direct influences on human, economic, and political aspects. Appropriate management of a resource requires its evaluation. The statistical study by Kohonen's self-organized classification (SOM) of hydrochemical data for the years 1995 and 2009 is used to process 47 samples distributed over the Haha region; it showed an evolution of the values of the parameters. Physico-chemical is a function of time and space with an increase in the values of the parameters, from the center of the study area towards the southwest.

This section of the book “World Protests: A Study of Key Protest Issues in the 21st Century” analyzes in-depth 2809 protests that occurred between 2006 and 2020 in 101 countries covering over 93% of the world population. This section focuses on: (i) major grievances and demands driving world protests, such as the failure of political representation/systems, anti-austerity, and for civil rights and global justice; (ii) who was demonstrating; (iii) what protest methods they used; (iv) who the protestors opposed; (v) what was achieved; and (vi) violence and repression in terms of arrests, injuries, and deaths.

The conclusion of “World Protests: A Study of Key Protest Issues in the 21st-Century” provides a summary of the content of the book: who protests, why and how they protest, as well as achievements and fallbacks. Protests have increased in all world regions, with demands articulated for real democracy, jobs, public services, social protection, civil rights, global justice and against austerity and corruption. The study also identifies 250 methods of protest and discusses selected topics such as inequality, the rise of radical right and women’s protests. The book calls on governments to listen and act on the main demands of protestors.

This section of the book “World Protests: A Study of Key Protest Issues in the 21st-Century” analyzes: (i) trends such as the rise of populism and radical right protests; (ii) anti-corruption and women’s protests; (iii) the link between inequality and protests, as well as the link between protests and perceptions that governments serve only the few; (iv) the Arab and the Latin American Springs; and (v) the link between protestors’ policy demands, Human Rights and internationally agreed UN development goals, calling on governments to act on them.

The Introduction of “World Protests: A Study of Key Protest Issues in the 21st Century” provides the background and methodology of the study, including the countries covered. It also describes the structure of the volume chapter by chapter, from protestors’ demands and methods to achievements and repression, guiding the reader through the content of the book. An annex presents 250 methods of non-violent protest.

Background Kidney transplantation (KT) is the optimal treatment for chronic end-stage renal failure. However, it is experiencing a huge delay in Morocco, and the lack of information on this alternative treatment could contribute to this delay. The purpose of our work is to evaluate the knowledge of hemodialysis (HD) on renal transplantation and to propose sensitization and information strategies. Methods This is a multicenter study conducted in 4 hemodialysis centers in Marrakesh from November to December 2017. An individual questionnaire was submitted to 310 patients concerning sociocultural status, willingness to be transplanted, the main benefits and risks of renal transplantation, knowledge of religious attitudes toward organ donation and transplantation, cost, and survival of the KT. Results Of the 310 patients, 56% were men, with a mean age of 49.43 ± 10.3 years. The mean duration of hemodialysis was 6.7 ± 5.3 years. Only 18% were in school, and 57% had moderate economic status. Of the 310 respondents, 71% said they wanted to be transplanted, and 15.5% believed that Islam was unfavorable by encouraging them to accept the fate that God chose for them. The rest were afraid of multiple complications and returning to dialysis. However, 41.7% thought transplantation was more expensive than hemodialysis. Only 65.8% believed that renal transplantation provided a better quality of life. Conclusions Raising the awareness of hemodialysis patients and their families is essential to promote KT in Morocco.

Background The aim of this study is to assess the corrosion resistance behaviour of Nickel-Titanium-based orthodontic wires (NiTi) in different concentrations of Sodium Fluoride (NaF) and the corrosion's inhibitory effect of the extracts of some medicinal plants (essential oils, hydrosols and extract). Material and methods In this study we used NiTi (3M) and CuNiTi (ORMCO, 35°C, California) orthodontic wires. The following electrolytes were prepared: Lactate Ringer solution with additions of 0.1%, 0.5% or 1% of Sodium Fluoride and the extracts of different plants: Artemisia, Syzygium aromaticum (Clove) and Celtis australis. Corrosion resistance was studied using anodic potentiodynamic polarisation and electrochemical impedance spectroscopy measurements. At the end of the experiment, microscopic images of wires were performed. ANOVA test with the comparison of Bonferroni and Tukey tests were performed to elucidate comparisons among all groups. Results The higher sodium fluoride concentration is related to negative corrosion potential for both NiTi and CuNiTi orthodontic wire. Hydrosols are associated to positive values of corrosion potential. CuNiTi has a lower corrosion resistance than NiTi. Conclusions The prescription of toothpastes containing sodium fluoride should be reduced especially for patients wearing fixed orthodontic appliances. Eugenol may be considered as alternative of sodium fluoride for orthodontic patients for its anti-microbial and anti-corrosive effects. Key words:Corrosion behaviour, Sodium Fluoride, Nickel-Tatanium, orthodontic wires, corrosion inhibitors, aromatical plants.

Prediction of daily global solar radiation (H) with simple and high accurate models would be beneficial for solar energy conversion systems. In this paper, we proposed a hybrid machine learning methodology integrating two feature selection methods and a Bayesian optimization algorithm to predict H in the city of Fez, Morocco. First, we identified the most significant predictors using two methods of feature importance: Mean Decrease in Impurity (MDI) and Permutation Feature Importance (PFI). Then, based on the feature selection results, ten models were developed and compared: (1) five standalone machine learning models including Classification and Regression Trees (CART), Random Forests (RF), Bagged Trees Regression (BTR), Support Vector Regression (SVR), and Multi-Layer Perceptron (MLP); and (2) the same models tuned by the Bayesian optimization (BO) algorithm: CART-BO, RF-BO, BTR-BO, SVR-BO, and MLP-BO. Both MDI and PFI techniques revealed that extraterrestrial solar radiation and sunshine duration fraction were the most influential features. The BO approach improved the predictive accuracy of MLP, CART, SVR, and BTR models and prevented the CART model from overfitting. Among the studied models, the SVR-BO algorithm provided the best trade-off between prediction accuracy (RMSE=0.4473kWh/m²/day, MAE=0.3381kWh/m²/day, and R²=0.9465), stability, and computational cost.

The purpose of this study is to give an efficient and practical method for mapping rosemary cover, which belongs to esparto grasslands. The approach consists of merging two technics: remote sensing and machine learning. At first, a set of vegetation indices was calculated using Sentinel 2A MSI image clipped for the study area. In a second place, a correlation test was executed to eliminate highly correlated indices. And so, three combinations were determined using the holden indices. After that, the model was trained using terrain truth samples. In the end, the model was applied to classify the image built, for the study area, by stacking the indices. The model was run for the study area, then validated using terrain sample points. Results are maps of rosemary cover densities corresponding to each combination. The validation test showed a score of 80, 67.5, and 75,5% respectively for combination 1, 2 and 3. This confirmed the selection of the first combination.

This work aims to present an efficient and practical method to mapping rosemary cover, which belongs to esparto grasslands. The approach consists of merging tow technics: remote sensing and machine learning. At first, three indices, normalized differenced vegetation index (NDVI), normalized differenced water index (NDWI), and soil adjusted vegetation index (SAVI), were calculated using Sentinel 2A MSI image clipped for the study area. In a second place, a set of terrain truth samples was used to train the model. In the end, the model was used to classify the RGB image built with the three spectral indices. The model was run for the study area, then validated by running it on another region and using samples. Results are maps of rosemary cover densities for both regions. The validation test showed a score of 90%, proving the efficiency of the model.

International audience

A database of 88 superficial sediment samples, distributed in space and time, was collected from the Sidi Chahed Dam (northeast of Meknes city, Morocco) and from four other reference stations (in the same region) located in supposedly uncontaminated environments. Analyses were focused on the physico-chemical characteristics and concentrations of heavy metals (Fe, Mn, As, Cu, Zn, Pb, Cr, Cd). The database was processed by advanced statistical analysis techniques. The method of classification by self-organizing maps (SOM) was used, permitting understanding and visualization of the spatial and temporal distribution of samples. Principal component analysis (PCA) and SOM hierarchical classification (SOM-HC) were used to validate the classification and detect seasonal variations in heavy metal concentrations. Dependencies between different metal tracers were considered and their spatio-temporal distribution is shown, together with the ranking of clusters, according to their pollution levels. Thus, autum...

This paper is about a shape optimization problem related to the Dirichlet Laplacian eigenvalues in the Euclidean plane. More precisely we study the shape of the minimizer in the class of open sets of constant width. We prove that the disk is not a local minimizer except for a limited number of eigenvalues.

Diverse waste materials have been adopted as sources of important phytochemicals with different medicinal applications. This work focuses on the application of pomegranate waste in curative medicine. Antimicrobial activity of extracts of punica granatum was evaluated, with two strain gram-negative Escherichia coli and Pseudomonas aeruginosa and two strain gram-positive Staphylococcus aureus and bacillus subtilis. The in vitro antibacterial activity was performed by agar disc diffusion method. The antibacterial activity of our extracts was most striking especially on Staphylococcus aureus. The significant antibacterial activity of active extracts was compared with the standard, antimicrobial, chloramphenicol (30 μg/disc). The results obtained in the present study suggest that pomegranate can be used in treating diseases of human organism.

Background Hemodialysis requires effective anticoagulation to avoid blood circuit clotting. In patients at high risk for bleeding, several alternative methods have been developed. Study Design Multicenter, prospective, randomized, crossover study evaluating the noninferiority of vitamin E–coated compared with heparin-coated dialyzers in a 4-hour heparin-free hemodialysis strategy. Settings & Participants 32 adult long-term hemodialysis patients from 2 French hemodialysis units with well-functioning fistulas or double-lumen catheters. Intervention Patients were randomly allocated to a first period using either vitamin E– or heparin-coated dialyzers. After a washout period of 2 hemodialysis sessions, each patient was switched to the alternative dialyzer for a second period. Each study period started with 2 hemodialysis sessions with reduced heparin dose (50% and 25% of usual heparin dose, respectively, for sessions 1 and 2) followed by 2 heparin-free sessions. Outcomes The primary end point was the percentage of successful study periods, defined as no circuit-clotting event leading to premature interruption of any of the 4 dialysis sessions. Secondary end points included total number and cumulative duration of hemodialysis sessions without clotting, number of saline solution flushes, dialysis circuit bubble trap status and dialyzer membrane status by visual inspection, and dialysis adequacy. Results The percentage of success with vitamin E–coated dialyzers (25/32 study periods [78%]) was not inferior to that with heparin-coated dialyzers (26/32 study periods [81%]). Visual inspection showed equal numbers of clean dialysis circuit bubble traps (vitamin E–coated, 34/121; heparin-coated, 32/120), whereas clean fiber bundles were more frequently noted with the vitamin E–coated compared with heparin-coated dialyzers (25/121 vs 2/120; P = 0.002). Limitations Results may not extrapolate to critically ill patients. Differences in dialyzer transparency may account for visual inspection scores. Conclusions The success rate of 4-hour heparin-free hemodialysis sessions is lower than that previously claimed in uncontrolled studies. Vitamin E–coated and heparin-coated dialyzers exposed patients to similar and unacceptable high failure rates. Further studies are required to improve heparin-free hemodialysis.

The 1,3-dipolar cycloaddition of arylnitriloxides on 1,2-dihydroisoquinoline derivatives led to new 3-aryl, 3a-8,9,9a-tetrahydro[5,4-c]-isoxazoloisoquinoline adducts. The regioselectivity of the cycloaddition reactions is discussed on the basis of 1H and 13C NMR data.

The chemotaxonomy of Moroccan rosemary was studied. The essential oil, which was obtained by hydrodistillation of Rosmarinus officinalis L. from different regions of Morocco (Rabat, Taforalt and Elateuf) was analyzed by GC and GC/MS. The variations in chemical composition are important between plant populations. We have defined three chemotypes of R. officinalis: the α-pinene-chemotype (α-pinene, 37–40% of the oil), the camphor-chemotype (camphor, 41–53% of the oil) and the 1,8-cineole-chemotype (1,8-cineole, 58–63% of the oil). The chemical composition of the 1,8-cineole-chemotype of R. officinalis was analyzed by GC and GC/MS. A total of 91 constituents were identified. The effect of harvest time on the oil production and chemical composition was examined on R. officinalis, and R. eriocalyx Jordan et Fourr., which were collected in the eastern Morocco from Elateuf and Debdou regions at different vegetative stages (from January to July). At full flowering, the oil yield was particularly high (1....

Ten novel homotopic 20-crown-6-ethers have been prepared from 1,3∶4,6-di-O-benzylidene-D-mannitol. Substituents could be introduced on the alditol framework after the macrocyclisation in order to modify their complexing abilities. In one case, a low but significant enantiomeric excess (32% ee) in favour of L(S)-phenylglycine methyl ester could be ascertained when two bulky vic-triazole substituents were associated into the vicinity of the cavity. The formation of an adjacent trans-fused ring on C-3/C-4 of the mannitol framework mediated the complexing abilities of these macrocycles toward 2-phenylglycine methyl ester perchlorates.

This study analyzes 843 protests occurring between January 2006 and July 2013 in 87 countries covering over 90% of world population. The paper focuses on: (i) major grievances driving world protests (ii) who is demonstrating, what protest methods they use, and who are they opposed to (iii) achievements and repression of social movements in the short term, and (iv) the main policy demands of world demonstrators. The paper calls for policy-makers to listen, whether messages are articulate or communicate only through frustration and violence.

Adjoint-based methods have been successfully applied by us to a number of inverse problems in shallow-water geoacoustics and acoustic tomography. These inversions were all performed in a range-independent context, using a finite-difference formulation of the wide-angle parabolic equation. In this study we consider realistic, fully range-dependent cases, where the bathymetry is variable and, more importantly, the medium properties (sound speed, density, attenuation) are variable in depth and range and can exhibit discontinuities. We adopt a finiteelement formulation, recently proposed in, and adapt it to our purposes. The finite-element method permits a geometrization and discretization that are consistent with site-specific boundaries and discontinuities. Finally, a modular graph approach is applied for generating, in a semi-automatic manner, the tangent-linear model and the back propagation needed for the gradient-based minimization of a mismatch cost function. This approach overcomes the two major difficulties of the inversion: the adjoint code is easily obtained (when compared to other automatic differentiation tools) and the subsequent minimization is rapid and robust. Various test cases will be presented that show the versatility of this new approach.

International audience; The global ocean biogeochemical models that are used in order to assess the ocean role in the global carbon cycle and estimate the impact of the climate change on marine ecosystems are getting more and more sophisticated. They now often account for several phytoplankton functional types that play particular roles in marine food webs and the ocean carbon cycle. These phytoplankton functional types have specific physiological characteristics, which are usually poorly known and therefore add uncertainties to model results. Indeed, this evolution in model complexity is not accompanied by a similar increase in the number and diversity of in situ data sets necessary for model calibration and evaluation. Thus, it is of primary importance to develop new methods to improve model performance using existing biogeochemical data sets, despite their current limitations. In this paper, we have optimized 45 physiological parameters of the PISCES global model, using a variational optimal control method. In order to bypass a global 3-D ocean variational assimilation, which would require enormous computation and memory storage, we have simplified the estimation procedure by assimilating monthly climatological in situ observations at five contrasted oceanographic stations of the JGOFS program in a 1-D version of the PISCES model. We began by estimating the weight matrix in the cost function by using heuristic considerations. Then we used this matrix to estimate the 45 parameters of the 1-D version of the PISCES model by assimilating the different monthly profiles (observed profiles at the five stations) in the same variational procedure on a time window of 1 year. This set of optimized parameters was then used in the standard 3-D global PISCES version to perform a 500 year global simulation. The results of both the standard and the optimized versions of the model were compared to satellite-derived chlorophyll-a images, which are an independent and global data set, showing that our approach leads to significant improvements in simulated surface chlorophyll-a in most of the regions of the world ocean. Besides demonstrating that we have improved the accuracy of the PISCES model, this study proposes a sound methodology that could be used to efficiently account for in situ data in biogeochemical ocean models.

International audience; This paper presents an improved variational method suitable for inverting a problem associated with integral constrains. The method allows a global minimization. We minimized a cost function representing the mismatch between the measurements and the output of a numerical model, to which we added a restoring term to a background. A way to process the covariance matrix associated with the above-weighted quadratic background is to model the control vectors using probabilistic principal component analysis (PPCA). The use of PPCA presents difficulties in the case of a large dataset representing the overall variability of the control space. We therefore developed a method based on a topological map model, which allows partition of the dataset into subsets more suited to the PPCA approach and thus leading to a local inversion by the variational method. A random walk based on a Markov chain was used to find the most appropriate subsets of the topological map by taking into account a priori information on the unknown vector. This random walk on a topological map allows us to reduce the number of subsets able to give the optimal solution and thus to achieve a better performance at a lower cost. An example of the application of this method to the shallow water acoustic tomography inverse problem, showing its effectiveness, is presented.

Ten novel homotopic 20-crown-6-ethers have been prepared from 1,3∶4,6-di-O-benzylidene-D-mannitol. Substituents could be introduced on the alditol framework after the macrocyclisation in order to modify their complexing abilities. In one case, a low but significant enantiomeric excess (32% ee) in favour of L(S)-phenylglycine methyl ester could be ascertained when two bulky vic-triazole substituents were associated into the vicinity of the cavity. The formation of an adjacent trans-fused ring on C-3/C-4 of the mannitol framework mediated the complexing abilities of these macrocycles toward 2-phenylglycine methyl ester perchlorates.

A meroditerpenoid metabolite has been isolated from the brown alga Cystoseira tamariscifolia and characterized as methoxybifurcarenone, by spectral analysis. Methoxybifurcarenone possesses antifungal activity against three tomato pathogenic fungi: Botrytis cinerea, Fusarium oxysporum sp. mycopersici and Verticillium alboatrum and antibacterial activity against Agrobacterium tumefaciens and Escherichia coli.

The 1,3-dipolar cycloaddition of arylnitriloxides on 1,2-dihydroisoquinoline derivatives led to new 3-aryl, 3a-8,9,9a-tetrahydro[5,4-c]-isoxazoloisoquinoline adducts. The regioselectivity of the cycloaddition reactions is discussed on the basis of 1H and 13C NMR data.

International audience; Over the past two years the capabilities of adjoint-based inversion have been explored for applications both in geoacoustic inversion and shallow-water acoustic tomography. Starting from case studies based on the principles of optimal control theory the performance of adjoint modeling has been constantly improved to more realistic scenarios ever since. In particular, the concept of semi-automatic adjoint generation has been introduced for inversion of satellite ocean colour imagery and geoacoustic characterization of seabed properties. In the framework of a Maritime Rapid Environmental Assessment sea trial (MREA/BP07) that was conducted in the same area south of the island of Elba as the earlier Yellow Shark experiment (YS94), this paper examines the original YS94 geoacoustic data and the recent MREA07 oceanographic data to demonstrate adjoint-based acoustic monitoring of environmental parameters in Mediterranean shallow waters. First, the adjoint-generated environmental gradients are validated for an application in geoacoustic inversion where the bottom geoacoustic parameters of the layered seabed are determined from long range acoustic propagation data in the water column. Then, for the application in ocean acoustic tomography, the temporal variability of MREA/BP07 sound-speed field data is analyzed in terms of empirical orthogonal functions and the adjoint-based approach is used to track the time-varying sound speed profile of the experimental transect.

This paper presents a variational methodology for inverting shallow water acoustic tomography (SWAT) measurements. The aim is to determine the vertical profile of the speed of sound c(z), knowing the acoustic pressures generated by a frequency source and collected by a sparse vertical hydrophone array (VRA). A variational approach that minimizes a cost function measuring the distance between observations and their modeled equivalents is used. A regularization term in the form of a quadratic restoring term to a background is also added. To avoid inverting the variance–covariance matrix associated with the above-weighted quadratic background, this work proposes to model the sound speed vector using probabilistic principal component analysis (PPCA). The PPCA introduces an optimum reduced number of non-correlated latent variables ?, which determine a new control vector and a new regularization term, expressed as ?T?. The PPCA represents a rigorous formalism for the use of a priori information and allows an efficient implementation of the variational inverse method.

Paris, June 29- July 4; We present an Ocean Acoustic Tomography (OAT) inversion in a shallow water environment. The idea is to determine the celerity $c(z),\;z$ is depth, knowing the acoustic pressures caused by a multiple frequencies source and collected by a sparse receiver array. The variational approach minimizes a cost function which measures the adequacy between the measurements and their forward model equivalent. This method introduces also a regularization term in the form $(c(z)-c_b(z))^TB^{-1}(c(z)-c_b(z))$, which supposes that $c(z)$ follows an \textit{a priori} normal law. To circumvent the problem of estimating $B^{-1},$ we propose to model the celerity vectors by a probabilistic PCA. In contrast to the methods which use PCA as a regularization method and filter the useful information, we take a sufficient number of axes which allow the modelization of useful information and filter only the noise. The probabilistic PCA introduces a reduced number of non correlated latent variables $\eta$ which act as new control parameters introduced in the cost function. This new regularization term, expressed as $\eta^T\eta,$ reduces the optimization computation time. In the following we apply the probabilistic PCA to an OAT problem, and present the results obtained when performing twin experiments.

In the framework of the recent Maritime Rapid Environmental Assessment sea trial MREA07/BP'07 [Le Gac&Hermand, 2007] that was conducted in the same area south of the island of Elba as the earlier Yellow Shark trial (YS94), this paper examines the original YS94 acoustic data and the recent MREA07 oceanographic data to demonstrate adjoint‐based acoustic monitoring of environmental parameters in Mediterranean shallow waters. First, adjoint‐generated environmental gradients are validated for the application in geoacoustic inversion where the bottom acoustic parameters of the YS94 layered seabed are determined from the long‐range waterborne propagation of a multi‐frequency signal. Then, for the application in ocean acoustic tomography, the temporal variability of the MREA07/BP'07 oceanographic data is analyzed in terms of empirical orthogonal functions and the adjoint‐based inversion scheme is used to track the time‐varying sound speed profile of the experimental transect.

International audience; In this paper a semi-automatic adjoint approach for variational data inversion is proposed. To demonstrate the effectiveness of the approach two illustrative examples are presented: the geoacoustic characterization of a Mediterranean shallow water environment using realistic experimental conditions and the estimation of oceanic and atmospheric constituents from satellite ocean colour imagery. In the first case geoacoustic parameters of the seabed (density, sound speed and attenuation) are determined from long/medium range underwater acoustic propagation data in the water column. In the second case the aerosol optical thickness in the atmosphere and the phytoplankton concentration in the ocean (chlorophyll-a) are estimated from solar reflectance measurements obtained with ocean colour sensors on board satellites. The general methodology for both applications is based on a modular graph concept that allows a straightforward adjoint computation by means of gradient backpropagation. Generation and coding of the adjoint models in both cases are accomplished with an algorithmic tool.

Recently, a numerical extension of the wide-angle PE (WAPE) adjoint-based inversion method has been presented that allows direct inversion of the geoacoustic parameters that are embedded in a discrete representation of nonlocal boundary conditions at the water-sediment interface [Hermand et al., ICTCA 2005]. In contrast to conventional ocean acoustic tomography (OAT), correct modeling of sound interaction with the bottom is particularly important for shallow water acoustic tomography (SWAT). Uncertainty or partial knowledge of the bottom acoustic parameters can significantly degrade SWAT performance. In this context the paper discusses an adjoint-based tomography approach that includes the geoacoustic parameters as additional unknowns in the parameter space. A priori information about the bottom characteristics, e.g., the approximate thickness and composition of sediment layers and hard rock basement are often available from site surveys with sub-bottom profiling systems or in the form of previously archived in situ data. This information can be used as an initial solution to start the inversion process or be included in an augmented cost function through the use of regularization. By means of adjoint modeling exact gradient information can be obtained to determine the sound speed profile of the water column and concomitantly adjust the partially known sediment and bottom halfspace parameters. A case study based on environmental data obtained in Mediterranean shallow waters is used to present first results.

Recently the concept of adjoint modeling has been introduced in shallow water acoustics for solving inverse problems. Analytical adjoints have been derived for normal modes and for both the standard parabolic equation and Claerbout’s wide-angle approximation (WAPE). This paper proposes the application of a semiautomatic adjoint approach that has been successfully applied in the past for multidimensional variational data assimilation in meteorological and climate modeling. Starting from a modular graph representation of the underlying forward model, a programming tool facilitates the generation and coding of both the tangent linear and the adjoint models. The potential of this numerical adjoint approach for the physical characterization of a shallow water environment is illustrated with two applications for geoacoustic inversion and ocean acoustic tomography using Claerbout’s WAPE in combination with nonlocal boundary conditions. Furthermore, the adjoint optimization is extended to multiple frequencies and it is shown how a broadband approach can enhance the performance of the inversion process. For a sparse array geometry in particular, the generalization of the adjoint-based approach to a joint optimization across multiple frequencies is necessary to compensate for the lack of vertical sampling of the propagation modes. Results with test data synthesized from geoacoustic inversion experiments in the Mediterranean show that with the numerical adjoint approach the acoustic field, the sound speed profile in the water column and the bottom properties can be efficiently retrieved.

Recently, an analytic adjoint-based method of optimal nonlocal boundary control has been proposed for inversion of a waveguide acoustic field using the wide-angle parabolic equation [Meyer and Hermand, J. Acoust. Soc. Am. 117, 2937-2948 (2005)]. In this paper a numerical extension of this approach is presented that allows the direct inversion for the geoacoustic parameters which are embedded in a discrete representation of the nonlocal boundary condition. The adjoint model is generated numerically and the inversion is carried out jointly across multiple frequencies. To demonstrate the effectiveness of the implemented numerical adjoint, an illustrative example is presented for the geoacoustic characterization of a Mediterranean shallow water environment using realistic experimental conditions.

Recently, an analytic adjoint-based method of optimal nonlocal boundary control has been proposed for inversion of a waveguide acoustic field using the wide-angle parabolic equation [Meyer and Hermand, J. Acoust. Soc. Am. 117, 2937–2948 (2005)]. In this paper a numerical extension of this approach is presented that allows the direct inversion for the geoacoustic parameters which are embedded in a spectral integral representation of the nonlocal boundary condition. The adjoint model is generated numerically and the inversion is carried out jointly across multiple frequencies. The paper further discusses the application of the numerical adjoint PE method for ocean acoustic tomography. To show the effectiveness of the implemented numerical adjoint, preliminary inversion results of water sound-speed profile and bottom acoustic properties will be shown for the YELLOW SHARK ’94 experimental conditions.