A hierarchical model to estimate the abundance and biomass of salmonids by using removal sampling and biometric data from multiple locations

We present a Bayesian hierarchical model to estimate the abundance and the biomass of brown trout (Salmo trutta fario) by using removal sampling and biometric data collected at several stream sections. The model accounts for (i) variability of the abundance with fish length (as a distribution mixture), (ii) spatial variability of the abundance, (iii) variability of the catchability with fish length (as a logit regression model), (iv) spatial variability of the catchability, and (v) residual variability of the catchability with fish. Model measured variables are the areas of the stream sections as well as the length and the weight of the caught fish. We first test the model by using a simulated dataset before using a 3-location, 2-removal sampling dataset collected in the field. Fifteen model alternatives are compared with an index of complexity and fit by using the field dataset. The selected model accounts for variability of the abundance with fish length and stream section and variability of the catchability with fish length. By using the selected model, 95% credible interval estimates of the abundances at the three stream sections are (0.46,0.59), (0.90,1.07), and (0.56,0.69) fish/m2. Respective biomass estimates are (9.68, 13.58), (17.22, 22.71), and (12.69, 17.31) g/m2

Microcellular Foaming of Polymethylmethacrylate in a Batch Supercritical CO2 Process: Effect of Microstructure on Compression Behavior

Microcellular foaming of reinforced core/ shell Polymethylmethacrylate (PMMA) was carried out bymeans of supercritical CO2 in a single-step process. Samples were produced using a technique based on the saturation of the polymer under high pressure of CO2(300 bars,40 C), and cellular structure was controlled by varying the depressurization rate from 0.5 bar/s to 1.6 x10-2 bar/sleading to cell sizes from 1lm to 200l m, and densities from 0.8 to 1.0 g/cm3. It was found that the key parameter to control cell size was depressurization rate, and larger depressurization rates generated bigger cell sizes. On the other hand, variation of the density of the samples was not so considerable. Low rate compression tests were carried out, analyzing the dependence of mechanical parameters such as elastic modulus, yield stress and densification strain with cell size. Moreover, the calculation of the energy absorbed for each sample is presented, showing an optimum of energy absorption up to 50% of deformation in the micrometer cellular range (here at a cell size of about 5 µm). To conclude, a brief comparison between neat PMMA and the core/shell reinforced PMMA has been carried out, analyzing the effect of the core/shell particles in the foaming behavior and mechanical properties

Comparison of MPEG-7 descriptors for long term selection of reference frames

During the last years, the amount of multimedia content has greatly increased. This has multiplied the need of efficient compression of the content but also the ability to search, retrieve, browse, or filter it. Generally, video compression and indexing have been investigated separately. However, as the amount of multimedia content grows, it will be very interesting to study representations that, at the same time, provide good compression and indexing functionalities. Moreover, even if the indexing metadata is created for functionalities such as search, retrieval, browsing, etc., it can also be employed to increase the efficiency of current video codecs. Here, we use it to improve the long term prediction step of the H.264/AVC video codec. This paper focuses on the comparison between four different MPEG-7 descriptors when used in the proposed scheme.Peer ReviewedPostprint (published version

On sequencing policies for unit-load automated storage and retrieval systems

Automated Storage and Retrieval System (AS/RS) performance high ly depends on the characteristics of the mechanical equipment. However, once the system has been physically implemented, achieving its maxim um efficiency depends on the wa y the system is operated. This paper it shows that request sequencing (i.e., planning the orde r in which storage and retrieval requests are performed) is of p aramount importance in AS/RS per formance. This paper reviews and adapts the most popular storage and sequencing policies to dynamic contexts, and then it proposes a “sequencing mathematical model” (SMM) to simultaneou sly solve the sequencing and storage location problems. Extensive computational results based on a thorough simulation experiment plan confirm that performing the requests in the rig ht sequence can have a positive impact on AS/RS performance. O ur results show that the proposed sequencing mathematical model regularly outperforms other methods. When used in a dynam ic context, the proposed SMM may yield up to a 25% reducti on in average travel-time comp ared to the situation where a no-sequencing method is applied

Sequencing approaches for multiple-aisle automated storage and retrieval systems

Automated storage and retrieval systems (AS/RS) are used in high velocity distribution centres to provide accurate and fast order processing. While almost every industrial system is comprised of many aisles, most of the academic research on the operational aspects of AS/RS is devoted to single-aisle systems, probably due to the broadly accepted hypothesis proposing that an m aisles system can be modelled as m 1-aisle independent systems. In this article, we present two multi-aisles sequencing approaches and evaluate their performance when all the aisles are managed independently first, and then in a global manner. Computational experiments conducted on a multi-aisle AS/RS simulation model clearly demonstrate that a multi-aisle system cannot be accurately represented by multiple single-aisle systems. The numerical results demonstrate that, when dealing with random storage, globally sequencing multi-aisle AS/RS leads to makespan reductions ranging from 14 to 29% for 2- and 3-aisle systems, respectivelyKeywords: automated storage and retrieval systems; multi-aisle; sequencing; simulatio

On the mean Euler characteristic and mean Betti numbers of the Ising model with arbitrary spin

12 pagesThe behaviour of the mean Euler-Poincaré characteristic and mean Betti's numbers in the Ising model with arbitrary spin on \mathbbm{Z}^2 as functions of the temperature is investigated through intensive Monte Carlo simulations. We also consider these quantities for each color $a$ in the state space $S_Q = \{ - Q, - Q + 2, \ldots, Q \}$ of the model. We find that these topological invariants show a sharp transition at the critical point

Amplitude modulation of vowel glottal pulses: application to sleep inertia

International audienceHuman voice carries non-linguistic information about emotion, fatigue, stress, truth, psychological illnesses etc. The proofs of this are well-established nowadays. In real-life situations, in laboratory conditions and from a cross-cultural point of view, the speakers psycho-physiological disorders induce vocal modifications. Many acoustic parameters are measured. They belong to the dynamic and spectral planes. Phase space is also involved. Amplitude modulation is one of them. Unlike prosody and vocal quality features, this has not been widely studied. In this paper, a method for estimation vowel glottal pulses amplitude modulations is proposed. After pulse detection, a sinusoidal fit is applied leading to an estimate of the amplitude modulation frequency. This method has already been used in experiments on sleep inertia effects on the voice. A pilot is suddenly awakened to undertake aeronautical psychomotor tasks. Results show the existence of an amplitude modulation. Their validity is based on determination coefficient measurements taking into account the number of pitch periods. Additionally, shimmer measurements show an increase after awakening. It can thus be concluded that sleep inertia has an effect on vowels uttered by the pilot