Combustion diagnostic methods based on the in-cylinder pressure signal are extensively used for c... more Combustion diagnostic methods based on the in-cylinder pressure signal are extensively used for calculating the heat release law or the burned fuel mass as well as the mean gas temperature from combining both the ®rst principle of thermodynamics and the state equation. In both equations the instantaneous gas composition has great in¯uence, even through the internal energy or through the gas constant. In the proposed method the gas is supposed to be composed of pure air, gaseous fuel and products of a stoichiometric combustion, neglecting the eect of local conditions (local mixing ratios and temperatures), but including their bulk temperature dependence. The concentration in the gas of each of these species was related with engine test parameters. A thermodynamic approach, coherent with the mentioned species distinction, is also proposed. The results of temperature correlations of the main thermodynamic properties are presented, as well as some results of the combustion diagnostic procedure from engine tests with dierent exhaust gas recirculation ratios. #
This paper gives a tutorial on the techniques and reference models used in digital watermarking. ... more This paper gives a tutorial on the techniques and reference models used in digital watermarking. Distorsions, attacks and applications are described in some detail. Finally, the need for benchmarking is discussed
In this paper, a spread-spectrum-like discrete cosine transform domain (DCT domain) watermarking ... more In this paper, a spread-spectrum-like discrete cosine transform domain (DCT domain) watermarking technique for copyright protection of still digital images is analyzed. The DCT is applied in blocks of 8 × 8 pixels as in the JPEG algorithm. The watermark can encode information to track illegal misuses. For flexibility purposes, the original image is not necessary during the ownership verification process, so it must be modeled by noise. Two tests are involved in the ownership verification stage: watermark decoding, in which the message carried by the watermark is extracted, and watermark detection, which decides whether a given image contains a watermark generated with a certain key. We apply generalized Gaussian distributions to statistically model the DCT coefficients of the original image and show how the resulting detector structures lead to considerable improvements in performance with respect to the correlation receiver, which has been widely considered in the literature and makes use of the Gaussian noise assumption. As a result of our work, analytical expressions for performance measures such as the probability of error in watermark decoding and probabilities of false alarm and detection in watermark detection are derived and contrasted with experimental results.
An overview of channel coding techniques for data hiding in still images is presented. Use of cod... more An overview of channel coding techniques for data hiding in still images is presented. Use of codes is helpful in reducing the bit error probability of the decoded hidden information, thus increasing the reliability of the system. First, the data hiding problem is statistically modeled for the spatial and DCT domains. Then, the bene"ts brought about by channel diversity are discussed and quanti"ed. We show that it is possible to improve on this basic scheme by employing block, convolutional and orthogonal codes, again giving analytical results. It is shown that the use of superimposed pulses does not produce any bene"t when applying them to data hiding. The possibility of using codes at the &sample level' (that is, without repeating every codeword symbol) is introduced and its potential analyzed for both hard-and soft-decision decoding. Concatenated and turbo coding are also discussed as ways of approaching the hidden channel capacity limit for the sample level case. Finally, experimental results supporting our theoretical approach are presented for some cases of interest.
A considerable amount of attention has been lately payed to a number of data hiding methods based... more A considerable amount of attention has been lately payed to a number of data hiding methods based in quantization, seeking to achieve in practice the results predicted by Costa for a channel with side information at the encoder. With the objective of filling a gap in the literature, this paper supplies a fair comparison between significant representatives of both this family of methods and the former spread-spectrum approaches that make use of near-optimal ML decoding; the comparison is based on measuring their probabilities of decoding error in the presence of channel distortions. Accurate analytical expressions and tight bounds for the probability of decoding error are given and validated by means of Monte Carlo simulations. For Dithered Modulation (DM) a novel technique that allows to obtain tighter bounds to the probability of error is presented. Within the new framework, the strong points and weaknesses of both methods are distinctly displayed. This comparative study allows us to propose a new technique named "Quantized Projection" (QP), which by adequately combining elements of those previous approaches, produces gains in performance.
Counts of Escherichia coli, faecal streptococci and enterococci were made on faecal specimens fro... more Counts of Escherichia coli, faecal streptococci and enterococci were made on faecal specimens from human and animal origin and urban raw sewage waters, with microtiter plates containing selective substances. Escherichia coli was more numerous than faecal streptococci and enterococci in 80% of the samples regardless of the origin. Consequently the use of the ratio E. coli/faecal streptococci to distinguish human from animal origin of faecal pollution is questionable. Enterococcus faecalis was predominant in human and poultry faeces, Streptococcus bovis was typical of the bovine faeces and to a lesser extent also of pig faeces whereas Enterococcus durans, Ent. hirae and Ent. faecium did not characterize any faecal source. Streptococcus bovis could be distinguished in the mictrotiter plate by its inability to reduce triphenyl tetrazolium chloride (TTC) in the medium.
The circumrotation of a submolecular fragment in either direction in a synthetic molecular struct... more The circumrotation of a submolecular fragment in either direction in a synthetic molecular structure is described. The movement of a small ring around a larger one occurs through positional displacements arising from biased Brownian motion that are kinetically captured and then directionally released. The sense of rotation is governed solely by the order in which a series of orthogonal chemical transformations is performed. The minimalist nature of the [2]catenane flashing ratchet design permits certain mechanistic comparisons with the Smoluchowski-Feynman ratchet and pawl. Even when no work has to be done against an opposing force and no net energy is used to power the motion, a finite conversion of energy is intrinsically required for the molecular motor to undergo directional rotation. Nondirectional rotation has no such requirement.
Combustion diagnostic methods based on the in-cylinder pressure signal are extensively used for c... more Combustion diagnostic methods based on the in-cylinder pressure signal are extensively used for calculating the heat release law or the burned fuel mass as well as the mean gas temperature from combining both the ®rst principle of thermodynamics and the state equation. In both equations the instantaneous gas composition has great in¯uence, even through the internal energy or through the gas constant. In the proposed method the gas is supposed to be composed of pure air, gaseous fuel and products of a stoichiometric combustion, neglecting the eect of local conditions (local mixing ratios and temperatures), but including their bulk temperature dependence. The concentration in the gas of each of these species was related with engine test parameters. A thermodynamic approach, coherent with the mentioned species distinction, is also proposed. The results of temperature correlations of the main thermodynamic properties are presented, as well as some results of the combustion diagnostic procedure from engine tests with dierent exhaust gas recirculation ratios. #
This paper gives a tutorial on the techniques and reference models used in digital watermarking. ... more This paper gives a tutorial on the techniques and reference models used in digital watermarking. Distorsions, attacks and applications are described in some detail. Finally, the need for benchmarking is discussed
In this paper, a spread-spectrum-like discrete cosine transform domain (DCT domain) watermarking ... more In this paper, a spread-spectrum-like discrete cosine transform domain (DCT domain) watermarking technique for copyright protection of still digital images is analyzed. The DCT is applied in blocks of 8 × 8 pixels as in the JPEG algorithm. The watermark can encode information to track illegal misuses. For flexibility purposes, the original image is not necessary during the ownership verification process, so it must be modeled by noise. Two tests are involved in the ownership verification stage: watermark decoding, in which the message carried by the watermark is extracted, and watermark detection, which decides whether a given image contains a watermark generated with a certain key. We apply generalized Gaussian distributions to statistically model the DCT coefficients of the original image and show how the resulting detector structures lead to considerable improvements in performance with respect to the correlation receiver, which has been widely considered in the literature and makes use of the Gaussian noise assumption. As a result of our work, analytical expressions for performance measures such as the probability of error in watermark decoding and probabilities of false alarm and detection in watermark detection are derived and contrasted with experimental results.
An overview of channel coding techniques for data hiding in still images is presented. Use of cod... more An overview of channel coding techniques for data hiding in still images is presented. Use of codes is helpful in reducing the bit error probability of the decoded hidden information, thus increasing the reliability of the system. First, the data hiding problem is statistically modeled for the spatial and DCT domains. Then, the bene"ts brought about by channel diversity are discussed and quanti"ed. We show that it is possible to improve on this basic scheme by employing block, convolutional and orthogonal codes, again giving analytical results. It is shown that the use of superimposed pulses does not produce any bene"t when applying them to data hiding. The possibility of using codes at the &sample level' (that is, without repeating every codeword symbol) is introduced and its potential analyzed for both hard-and soft-decision decoding. Concatenated and turbo coding are also discussed as ways of approaching the hidden channel capacity limit for the sample level case. Finally, experimental results supporting our theoretical approach are presented for some cases of interest.
A considerable amount of attention has been lately payed to a number of data hiding methods based... more A considerable amount of attention has been lately payed to a number of data hiding methods based in quantization, seeking to achieve in practice the results predicted by Costa for a channel with side information at the encoder. With the objective of filling a gap in the literature, this paper supplies a fair comparison between significant representatives of both this family of methods and the former spread-spectrum approaches that make use of near-optimal ML decoding; the comparison is based on measuring their probabilities of decoding error in the presence of channel distortions. Accurate analytical expressions and tight bounds for the probability of decoding error are given and validated by means of Monte Carlo simulations. For Dithered Modulation (DM) a novel technique that allows to obtain tighter bounds to the probability of error is presented. Within the new framework, the strong points and weaknesses of both methods are distinctly displayed. This comparative study allows us to propose a new technique named "Quantized Projection" (QP), which by adequately combining elements of those previous approaches, produces gains in performance.
Counts of Escherichia coli, faecal streptococci and enterococci were made on faecal specimens fro... more Counts of Escherichia coli, faecal streptococci and enterococci were made on faecal specimens from human and animal origin and urban raw sewage waters, with microtiter plates containing selective substances. Escherichia coli was more numerous than faecal streptococci and enterococci in 80% of the samples regardless of the origin. Consequently the use of the ratio E. coli/faecal streptococci to distinguish human from animal origin of faecal pollution is questionable. Enterococcus faecalis was predominant in human and poultry faeces, Streptococcus bovis was typical of the bovine faeces and to a lesser extent also of pig faeces whereas Enterococcus durans, Ent. hirae and Ent. faecium did not characterize any faecal source. Streptococcus bovis could be distinguished in the mictrotiter plate by its inability to reduce triphenyl tetrazolium chloride (TTC) in the medium.
The circumrotation of a submolecular fragment in either direction in a synthetic molecular struct... more The circumrotation of a submolecular fragment in either direction in a synthetic molecular structure is described. The movement of a small ring around a larger one occurs through positional displacements arising from biased Brownian motion that are kinetically captured and then directionally released. The sense of rotation is governed solely by the order in which a series of orthogonal chemical transformations is performed. The minimalist nature of the [2]catenane flashing ratchet design permits certain mechanistic comparisons with the Smoluchowski-Feynman ratchet and pawl. Even when no work has to be done against an opposing force and no net energy is used to power the motion, a finite conversion of energy is intrinsically required for the molecular motor to undergo directional rotation. Nondirectional rotation has no such requirement.
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Papers by Juan Hernandez