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Gas diffusion media (GDM) and flow fields perform the task of distributing the reactant gases uniformly over the active electrochemical area in proton exchange membrane (PEM) fuel cells. Carbon paper and carbon cloth are two commonly employed gas diffusion media in PEM fuel cells, and they differ widely in their structure and properties. Since the path of the reactant gases to the catalyst in the fuel cell electrodes involves passing through the flow fields as well as the GDM, a good design for a fuel cell requires an understanding of the interaction between these components. The focus of the present work is to study the impact of the difference in structure and properties of the diffusion media used, on the design of the PEM fuel cell flow field. Carbon paper and carbon cloth were characterized for the pressure drop they cause when used as GDMs, for channel intrusion, compressibility and electrical resistivity. Carbon cloth exhibits about 43-125% more intrusion into the channel in comparison with carbon paper for the conditions tested. This intrusion results in increased pressure drop in the flow channel especially at higher channel widths and at higher compression. Compression studies reveal that carbon cloth lacks compression rigidity and suffers considerable strain at lower stress values whereas carbon paper is relatively rigid in nature. The results indicate that the intrusion of carbon cloth into the channel, constraints the channel width in a flow field design if it were to be used with a carbon cloth GDM as opposed to a carbon paper GDM. Electrical resistivity measurements were carried out and a simple mathematical model has been developed for the potential drop in the GDM. The model indicates that even from the perspective of electrical properties, use of carbon cloth GDM constraints the channel width that is permissible in flow field design. � 2010 Elsevier Ltd.

The process of “hysteresis” has widely attracted the attention of researchers and investigators due to its usage in many disciplines of science and engineering. Economics, physics, chemistry, electrical, mechanical, and petroleum engineering are some examples of disciplines that encounter hysteresis. However, the meaning of hysteresis varies from one field to another, and therefore, many definitions occur for this phenomenon depending on the area of interest. The “hysteresis” phenomenon in petroleum engineering has gained the attention of researchers and investigators lately, because of the role that plays in reservoir engineering and reservoir simulation. Hysteretic effects influence reservoir performance. Therefore, an accurate estimation of rock and fluid property curves has an essential role in evaluating hydrocarbon recovery processes. In this paper, a comprehensive review of research and growth on the hysteresis of wettability for its applications in petroleum engineering is reported. Also, theoretical and experimental investigations of hysteresis of wettability are compared and discussed in detail. The review highlights a range of concepts in existing models and experimental processes for wettability hysteresis. Furthermore, this paper tracks the current development of hysteresis and provides insight for future trends in the research. Finally, it reveals an outlook on the research challenges and weaknesses of hysteresis of wettability.

The importance of adsorption-based biochemical/biological sensors in biochemistry and biophysics is paramount. Their temporal response gives information about the presence of a biochemical/biological analyte, its concentration and its interactions with the adsorption sites (which may be an integral part of the surface itself or immobilized functionalizing molecules). Mathematical models of the temporal response taking into account as many relevant effects as possible are essential for obtaining reliable information. We present a novel model taking into account the bimodal affinity of a sensing surface (adsorption occurs on two distinct site types), and the adsorption-caused depletion of the analyte from the sample. We perform qualitative and quantitative analysis of the analyte depletion influence on the bimodal adsorption, and of the influence of the sensing surface inhomogeneity on the sensor temporal response, for different analyte concentrations and different fractions of two types of adsorption sites. Since the presented mathematical model deals with the realistic cases of the sensing surface non-uniformity and the finite amount of analyte present in the sensor reaction chamber, it enables improved accuracy in interpreting the measurement data. Our results are general, i.e. valid for any adsorption sensor (microcantilevers, plasmonics) and for arbitrary sensor dimensions.

COVID-19 dynamics is one of the most relevant subjects nowadays, and, in this regard, mathematical modeling and numerical simulations are of special interest. This paper describes COVID-19 dynamics based on a novel version of the susceptible–exposed–infectious–removed model. Removed population is split into recovered and death populations allowing a better comprehension of real situations. Besides, the total population is reduced based on the number of deaths. Hospital infrastructure is also included into the mathematical description allowing the consideration of collapse scenarios. Initially, a model verification is carried out calibrating system parameters with data from China outbreak that is considered a benchmark due the availability of data for the entire cycle. Afterward, Brazil outbreak is of concern, calibrating the model and developing numerical simulations. Results show several scenarios highlighting the importance of social isolation and hospital infrastructure. System dynamics has a strong sensitivity to transmission rate showing the importance of numerical simulations to guide public health decision strategies. Results also show that complex dynamical responses can emerge due to the oscillations of the transmission rate, being associated with distinct infection subsequent waves.

‘Babassu’ mesocarp flour has been used by the pharmaceutical, human food and animal feed industries. However, there is lack of standardization in the production, as well as absence of information on the management of the product’s quality. Thus, the objective of this study was to dry the ‘babassu’ mesocarp in forced-air oven and solar dryer, adjust different mathematical models to the experimental data, as well as to quantify the levels of proteins and crude fiber of the produced flour. The criteria for the adjustment were the coefficient of determination, magnitude of the mean relative error, standard deviation of estimate and the residual distribution trend. Drying in the shortest time occurred in oven at 60 °C (370 min), leading to water content of 4.62%, while in the solar dryer the final water content was 8.07% in 6 days. The mathematical model Two Terms showed the best fit to the experimental data for oven drying and the Midilli model showed the best fit in solar dryer. There was an increase in protein content with the drying in solar dryer and oven at 40, 50 and 60 °C (1.36, 1.33, 1.15 and 1.37%, respectively) in relation to fresh mesocarp (0.88%). Drying in both oven and solar dryer promoted increase of protein in the flour. RESUMO A farinha do mesocarpo do babaçu tem sido utilizada pelas indústrias farmacêuticas e de alimentação humana e animal. Contudo, há falta de padronização na produção, bem como ausência de informações do manejo sobre a qualidade do produto. Deste modo, objetivou-se, no trabalho, secar o mesocarpo do babaçu em estufa de ventilação forçada de ar e secador solar, ajustar diferentes modelos matemáticos, bem como quantificar os teores de proteínas e fibras brutas da farinha produzida. Foram usados, como critério do ajuste, o coeficiente de determinação, a magnitude do erro médio relativo, o desvio-padrão da estimativa e a tendência de distribuição dos resíduos. A secagem em menor tempo ocorreu em estufa a 60 ºC (370 min) obtendo-se teor de água de 4,62%, enquanto no secador solar foi em 6 dias com teor de água final de 8,07%. O modelo Dois Termos foi o que melhor se ajustou aos dados experimentais para secagem em estufa e o modelo Midilli em secador solar. Houve um aumento do teor de proteína com a secagem em secador solar e estufa a 40, 50 e 60 ºC (1,36; 1,33; 1,15 e 1,37%, respectivamente) em relação ao mesocarpo in natura (0,88%). A secagem em estufa e em secador solar proporcionou incremento de proteína na farinha.

This short paper focuses on the role of mathematical models to analyze the impact of pandemics on health resources and the different trade-offs that may be included in them. There is a large body of literature suggesting that mathematical modeling may be helpful to estimate how much additional equipment and infrastructure are necessary to mitigate an increase in demand for health services during a large-scale outbreak of an infectious disease. I comment on the crucial role of these models with a special focus on their strengths and limitations.Este breve documento se centra en el papel de los modelos matemáticos para analizar el impacto de las pandemias en los recursos de salud y las diferentes trade-off que pueden estar presente. Existe una gran cantidad de literatura que sugiere que los modelos matemáticos pueden ser útiles para estimar cuánto equipo e infraestructura adicionales pueden ser necesarios para mitigar un aumento en la demanda de servicios de salud durante un brote a gran escala de una enfermedad infecciosa. Comento sobre el papel crucial de estos modelos con un enfoque especial en sus fortalezas y limitaciones.

[EN] In this work, the fouling mechanisms that dominate the ultrafiltration of residual brines from table olive packing plant wastewaters were investigated. For that purpose, Hermia's models adapted to crossflow filtration, resistance-in-series model and a model combining intermediate blocking and cake formation mechanisms were fitted to the experimental data. Tests were performed with a 5 kDa polyethersulfone membrane at transmembrane pressures between 1 and 3 bar and crossflow velocities between 2.2 and 3.7 m s(-1). Results demonstrated that the resistance-in-series model was the most accurate to predict permeate flux evolution with time. The predominant fouling mechanism was cake formation followed by intermediate blocking/adsorption. The fouling resistances that were determined by means of the resistance in series model were tested using a well-established mathematical model proposed by Mondal and De that also combines both fouling phenomena (intermediate pore blocking and cake formation). Results demonstrated that the predicted resistances are consistent with those determined by Mondal and De's model. (C) 2016 Elsevier Ltd. All rights reserved., The authors of this work wish to gratefully acknowledge the financial support of CDTI (Centre for Industrial Technological Development) depending on the Spanish Ministry of Science and Innovation (INNPRONTA program, ITP-20111020).

This paper aims to explain results of respirometry experiments using Activated Sludge Model No. 1. In cases of insufficient fit of ASM No. 1, further modifications to the model were carried out and the so-called “Enzymatic model” was developed. The best-fit method was used to determine the effect of the proposed modifications. Increased agreement was found between simulated data and respirometry results, particularly for repeated respirometric tests with acetate as the sole substrate. Additionally, the influence of different biomass pre-conditioning methods was examined. Results from repeated respirometric tests suggest that presence of residual products in an activated sludge sample before respiration testing may decrease the sample's activity and significantly affect results from respirometric tests. An innovative approach to recover original activity is suggested by washing activated sludge samples with tap water or “mineral medium”. As allylthiourea (ATU) was used in most experiments to suppress endogenous nitrification, its influence on kinetic parameters was reviewed. Respirometric tests confirmed that ATU addition has a significant effect on activity and respiration rate of activated sludge samples and could affect results of respirometric analyses.

Solid mixtures for refreshment are already totally integrated to the Brazilian consumers' daily routine, because of their quick preparation method, yield and reasonable price - quite lower if compared to 'ready-to-drink' products or products for prompt consumption, what makes them economically more accessible to low-income populations. Within such a context, the aim of this work was to evaluate the physicochemical and mineral composition, as well as the hygroscopic behavior of four different brands of solid mixture for mango refreshment. The BET, GAB, Oswim and Henderson mathematical models were built through the adjustment of experimental data to the isotherms of adsorption. Results from the physiochemical evaluation showed that the solid mixtures for refreshments are considerable sources of ascorbic acid and reductor sugar; and regarding mineral compounds, they are significant sources of calcium, sodium and potassium. It was also verified that the solid mixtures for refreshments of the four studied brands are considered highly hygroscopic.

The penile response profiles of homosexual and heterosexual pedophiles, hebephiles, and teleiophiles to laboratory stimuli depicting male and female children and adults may be conceptualized as a series of overlapping stimulus generalization gradients. This study used such profile data to compare two models of alloerotic responding (sexual responding to other people) in men. The first model was based on the notion that men respond to a potential sexual object as a compound stimulus made up of an age component and a gender component. The second model was based on the notion that men respond to a potential sexual object as a gestalt, which they evaluate in terms of global similarity to other potential sexual objects. The analytic strategy was to compare the accuracy of these models in predicting a man’s penile response to each of his less arousing (nonpreferred) stimulus categories from his response to his most arousing (preferred) stimulus category. Both models based their predictions on the degree of dissimilarity between the preferred stimulus category and a given nonpreferred stimulus category, but each model used its own measure of dissimilarity. According to the first model (“summation model”), penile response should vary inversely as the sum of stimulus differences on separate dimensions of age and gender. According to the second model (“bipolar model”), penile response should vary inversely as the distance between stimulus categories on a single, bipolar dimension of morphological similarity—a dimension on which children are located near the middle, and adult men and women are located at opposite ends. The subjects were 2,278 male patients referred to a specialty clinic for phallometric assessment of their erotic preferences. Comparisons of goodness of fit to the observed data favored the unidimensional bipolar model.

O bagaço de laranja úmido pode ser utilizado como adsorvente. A atividade de água é uma das variáveis que mais afetam o processo fermentativo e, consequentemente, o armazenamento deste material, razão pela qual, este trabalho teve como objetivo, a determinação das isotermas de sorção do bagaço de laranja nas temperaturas de 25, 35 e 50 °C, de modo a correlacionar a umidade com a atividade de água. Os teores de umidade de equilíbrio foram determinados pelo método estático utilizando-se soluções de sais para uma faixa de umidade relativa de 10 a 80%. Os modelos de Henderson, Chung-Pfost, Henderson Modificado, Halsey, Luikov e Motta Lima, foram ajustados aos dados experimentais, em que os resultados mostraram que as isotermas apresentaram forma sigmoidal e os modelos de Luikov e Halsey foram os que melhor representaram os dados de equilíbrio do bagaço de laranja. Wet bagasse can be used as an adsorbent in effluent treatment process. However, before its use a previous drying is necessary. The water activity is an important parameter that affects the fermentation process, and thus its determination becomes most important in order to store this adsorbent. Thus, the objective of this work is to determine the sorption isotherms of orange bagasse at 25, 35 and 50 °C temperatures in order to correlate the moisture with a water activity. The equilibrium moisture content was determined by the static method using salts solution for a 10-80% relative humidity range. The following models were fitted to the experimental data: Henderson, Chung-Pfost, Modified Henderson, Halsey, Luikov and Motta Lima. All models results followed a sigmodal-type function. The equilibrium data for the orange bagasse were better represented by the Luikov and Halsey models.

In a ferritic steel specimen cladded with austenitic stainless steel there is a change in mechanical and thermal properties at the interface causing residual stresses to develop. The residual stresses near the interface of a cladded specimen were examined by neutron diffraction, ring-core and deep-hole measurements and compared with a non-linear elastic-plastic finite element analysis.

Using the self-consistent field pseudopotential method we calculated the adhesive energy, perpendicular and lateral forces and barrier height between two rigid A1(001) slabs modeling the sample and a blunt tip. We found that the adhesive energy and forces are site specific, and can lead to a significant corrugation in the constant force mode with negative force gradient. Lateral forces, which determine friction on the atomic scale are not simply proportional to the perpendicular force, and are typically one order of magnitude smaller. Our results confirm that perpendicular tip force and barrier height are interrelated for separations where the force gradient is positive.

The three main currently proposed approaches for understanding specific ion effects are briefly described. In some experimentally well defined and simplified situations, one can decouple ion specificity effects from all others. Small globular micelles in water/salt mixtures are one of the simple situations where specific ion effects can be distinguished: 'hydrophobic ions' introduced by Hofmeister in the late 19th century, also called 'structure breaking' or 'salting in' ions, which are similar to 'soft ions' in the classification introduced by Pearson, are more strongly adsorbed on the micellar surface than predicted by electrostatics alone. Hence, lateral repulsions between surfactants are increased, resulting in a measurable and calculable decrease of micelle size when adsorbing anions such as bromide replace non-adsorbing anions such as chloride. © 2004 Elsevier Ltd. All rights reserved. 9 1-2 74 80 Cited By :36

This paper presents a high-fidelity electro-thermal model of a half-bridge that consists of IGBTs and anti-parallel diodes. The model calculates and estimates the half-bridge voltages, currents, switching and conduction losses considering the operating temperature and current conditions. Moreover, this model is suitable for varying switching frequency operation. The electro-thermal model can be used as an evaluation tool to analyze the performance of control strategies for traction inverter from efficiency, temperature and component stress point of view. In this paper performance of Direct Torque Model Predictive Control (DTMPC) of an Interior Permanent Magnet Synchronous Motor (IPMSM) is evaluated in comparison with Indirect Field Oriented Control (IFOC) with sinusoidal pulse width modulation (PWM). The inverter model and the MPC are both implemented in C-Mex for rapid execution. The MPC algorithm implemented in this research tracks torque reference while using Maximum-Torque-Per-Ampere (MTPA) strategy and minimizing switching losses. Both control systems are able to follow the speed reference. The MPC shows a decrease in losses compared to IFOC when tested with low-speed and high-speed parts of the WLTC profile.

The Clapper-Yule model is the only classical spectral reflection model for halftone prints that takes explicitly into account both the multiple internal reflections between the print-air interface and the paper substrate and the lateral propagation of light within the paper bulk. However, the Clapper-Yule model assumes a planar interface and does not take into account the roughness of the print surface. In order to extend the Clapper-Yule model to rough printing supports (e.g., matte coated papers or calendered papers), we model the print surface as a set of randomly oriented microfacets. The influence of the shadowing effect is evaluated and incorporated into the model. By integrating over all incident angles and facet orientations, we are able to express the internal reflectance of the rough interface as a function of the rms facet slope. By considering also the rough interface transmittances both for the incident light and for the emerging light, we obtain a generalization of the Clapper-Yule model for rough interfaces. The comparison between the classical Clapper-Yule model and the model extended to rough surfaces shows that the influence of the surface roughness on the predicted reflectance factor is small. For high-quality papers such as coated and calendered papers, as well as for low-quality papers such as newsprint or copy papers, the influence of surface roughness is negligible, and the classical Clapper-Yule model can be used to predict the halftone-print reflectance factors. The influence of roughness becomes significant only for very rough and thick nondiffusing coatings. © 2005 Optical Society of America.

In this paper, the issues related to short-circuit calculations in hybrid AC/DC microgrids are discussed. The reference standard for short-current calculations in DC systems is the IEC 61660, which provides a mathematical formulation of the problem. The standard only includes radial DC grids and does not consider a more complex system, such as meshed DC systems or a hybrid AC/DC microgrid. This paper proposes a generalized approach that can be used independently of the characteristics of the hybrid system. The proposed approach is applied to four test microgrids with different distributed sources and number of nodes and the results are compared with those obtained simulating the same grids with Neplan 360®.

Battery energy storage systems (BESS) have been extensively investigated to improve the efficiency, economy, and stability of modern power systems and electric vehicles (EVs). However, it is still challenging to widely deploy BESS in commercial and industrial applications due to the concerns of battery aging. This paper proposes an integrated battery life loss modeling and anti-aging energy management (IBLEM) method for improving the total economy of BESS in EVs. The quantification of BESS aging cost is realized by a multifactorial battery life loss quantification model established by capturing aging characteristics from cell acceleration aging tests.Meanwhile, a charging event analysis method is proposed to deploy the built life loss model in vehicle BESS management. Two BESS active anti-aging vehicle energy management models: vehicle to grid (V2G) scheduling and plug-in hybrid electric vehicle (PHEV) power distribution, are further designed, where the battery life loss quantification model is used to generate the aging cost feedback signals. The performance of the developed method is validated on a V2G peak-shaving simulation system and a hybrid electric vehicle. The work in this paper presents a practical solution to quantify and mitigate battery aging costs by optimizing energy management strategies and thus can further promote transportation electrification.

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works This paper proposes a comprehensive analysis of the Modular Multilevel Converter (MMC) focusing on the different arm applied voltage components, that this paper will refer as degrees of freedom (DOFs), which must be considered in order to perform the internal energy balancing of the converter. The analysis relies on the commonly used differential and additive reference frames. By means of a steady-state analysis, the different voltages components applied and currents components flowing through the converter are studied and an in-depth discussion of the roles of each DOF in the converter is presented. Furthermore, the mathematical expressions of the power exchanged between the AC/DC networks and within the converter, between the arms (vertical) and among phase-legs (horizontal), are derived considering all the DOFs of the MMC, revealing potential interactions among the differential and additive quantities. Finally, the theoretical analysis is validated through comparisons between the values obtained with the mathematical expressions and the simulation results assuming different case scenarios.

Numerical simulations offer a wide range of benefits. Therefore, they are widely used in research and development. One of the biggest benefits is the possibility of automated parameter variation. This allows testing different scenarios very quickly. Nevertheless, physical experiments in the laboratory or on a test rig are still, and will remain, necessary. Physical experiments offer benefits, e.g., for very complex and/or nonlinear systems and are required for the validation of numerical models. To enhance the quality of experimental NVH investigations and to make use of the benefits of numerical simulation during experimental investigations at the same time, numerical models can be integrated into physical test rigs using the mechanical hardware-in-the-loop (mHIL) method (also referred to as real-time dynamic substructuring, hybrid testing or active control of impedance). During experimental NVH testing, the device under test (DUT) is connected to a mHIL interface which in turn actively emulates the structural dynamics of the boundary condition based on a numerical target impedance model. The goal is to have realistic contact forces instead of blocked forces at the mounting points of the DUT. This paper illustrates the development and characterization of a modular mHIL interface with high bandwidth for NVH testing of a vehicle’s front axle. The physical emulation of structural dynamics based on a target impedance model is demonstrated for synthetic test cases (e.g., emulation of different stiffness settings, or multi-resonant behavior) up to 1 kHz. Furthermore, emulation of the vehicle chassis’ structural dynamics in a single spatial direction is shown for an NVH investigation on a single-axis chassis dynamometer.

Free Energy Principle underlies a unifying framework that integrates theories of origins of life, cognition, and action. Recently, FEP has been developed into a Markovian monist perspective (Friston et al. in BC 102: 227-260, 2020). The paper expresses scepticism about the validity of arguments for Markovian monism. The critique is based on the assumption that Markovian models are scientific models, and while we may defend ontological theories about the nature of scientific models, we could not read off metaphysical theses about the nature of target systems (self-organising conscious systems, in the present context) from our theories of nature of scientific models (Markov blankets). The paper draws attention to different ways of understanding Markovian models, as material entities, fictional entities, and mathematical structures. I argue that none of these interpretations contributes to the defence of a metaphysical stance (either in terms of neutral monism or reductive physicalism). This is because scientific representation is a sophisticated process, and properties of Markovian models-such as the property of being neither physical nor mental-could not be projected onto their targets to determine the ontological properties of targets easily.

This paper studies the trending behavior of the COVID-19 dynamics in Israeli cities. The model employed is used to describe, for each city, the accumulated number of cases, the number of cases per day, and the predicted final number of cases. The innovative analysis adopted here is based on the daily evolution of the predicted final number of infections, estimated with data available until a given date. The results discussed here are illustrative for six cities in Israel, including Jerusalem and Tel Aviv. They show that the model employed fits well with the observed data and is able to suitably describe the COVID-19 dynamics in a country strongly impacted by the disease that holds one of the most successful vaccination programs in the world.

Treballs Finals del Màster d'Economia, Facultat d'Economia i Empresa, Universitat de Barcelona. Curs: 2021-2022, Tutor: Josep Maria Izquierdo Aznar; Pedro Calleja Cortes, Greenhouse gas(GHGs) emissions have resulted in global warming which further leads to climate change. To reduce GHGs emissions, governors make attempts to create multilateral agreements among countries. Their failure of establishing sustainable agreements drives researchers to find fair and equitable distribution rules. Based on Emission Egalitarianism for each individual, this paper creatively generates the generalized constraint equal awards rule (GEA), provides corresponding algorithm to compute emission allocations from the GEA rule and points out several characteristics of this rule. To determine a fairer rule, this paper introduces Lorenz dominance and proved in n-agent case that the allocation provided by the GEA rule is Lorenz-undominated by all other allocations from any other rules. Furthermore, in a simplified 2-agent case this paper confirmed the allocations derived from the GEA rule Lorenz dominates all other allocations from any other rules.

This paper introduces a new mathematical model that is used to compute either the interfacial tension of quiescent axisymmetric pendant/sessile drops and pendant/captive bubbles. This model consists of the Young–Laplace equation, that describes interface shape, together with suitable boundary conditions that guarantee a prescribed volume of drops/bubbles and a fixed position in the capillary. In order to solve the problem numerically, the Young–Laplace equation is discretized by using numerical differentiation and the numerical solutions are obtained applying the well-know Newton method. The paper contains a validation of the new methodology presented for what theoretical bubble/drops are used. Finally, some numerical results are presented for both drops and bubbles of water as well as several surfactant solutions to demonstrate the applicability, versatility and reproducibility of the proposed methodology., RSC Advances, 9 (28), ISSN:2046-2069

Locusts are short horned grasshoppers that exhibit two behaviour types depending on their local population density. These are: solitarious, where they will actively avoid other locusts, and gregarious where they will seek them out. It is in this gregarious state that locusts can form massive and destructive flying swarms or plagues. However, these swarms are usually preceded by the aggregation of juvenile wingless locust nymphs. In this paper we attempt to understand how the distribution of food resources affect the group formation process. We do this by introducing a multi-population partial differential equation model that includes non-local locust interactions, local locust and food interactions, and gregarisation. Our results suggest that, food acts to increase the maximum density of locust groups, lowers the percentage of the population that needs to be gregarious for group formation, and decreases both the required density of locusts and time for group formation around an optimal food width. Finally, by looking at foraging efficiency within the numerical experiments we find that there exists a foraging advantage to being gregarious., Author summary Locusts are short horned grass hoppers that live in two diametrically opposed behavioural states. In the first, solitarious, they will actively avoid other locusts, whereas the second, gregarious, they will actively seek them out. It is in this gregarious state that locusts form the recognisable and destructive flying adult swarms. However, prior to swarm formation juvenile flightless locusts will form marching hopper bands and make their way from food source to food source. Predicting where these hopper bands might form is key to controlling locust outbreaks. Research has shown that changes in food distributions can affect the transition from solitarious to gregarious. In this paper we construct a mathematical model of locust-locust and locust-food interactions to investigate how food distributions affect the aggregation of juvenile locusts, termed groups, an important precursor to hopper bands. Our findings suggest that there is an optimal food distribution for group formation and that being gregarious increases a locusts ability to forage when food becomes more patchy.

This paper presents experimental results in damping the pitch motion on a Surface Effect Ship (SES) in high vessel speeds in presence of regular wave. The SES is a marine craft supported by pressurized air cushion. It consists of two side-hulls, a flexible rubber bow and reinforced stern seal. The air cushion is pressurized thanks to the lift fans blowing air into the cushion. Modern SES are equipped with controllable vent valves that allows adjusting the pressure of the air cushion. Air Split Cushion SES is one of the new design by Umoe Mandal AS where the main air cushion is divided to four smaller air chambers, each one equipped with a lift fan and controllable vent-valve. Using a derivative controller, this paper presents an active pitch control in waves. Controlling the pressure in each air cushion through adjusting the air leakage on the vent-valve, provides an effective pitch regulator that demonstrates, through simulations and experiments, reduction of up to 60 % of the pitch motion in waves and high speeds. The effectiveness of the proposed system is examined through experimental model testing of the vehicle in SINTEF Ocean's towing tank.

G-protein coupled receptor (GPCR) mediated calcium (Ca2+)-signaling transduction remains crucial in designing drugs for various complex diseases including neurodegeneration, chronic heart failure as well as respiratory diseases. Although there are several reviews detailing various aspects of Ca2+-signaling such as the role of IP3 receptors and Ca2+-induced-Ca2+-release, none of them provide an integrated view of the mathematical descriptions of GPCR signal transduction and investigations on dose-response curves. This article is the first study in reviewing the network structures underlying GPCR signal transduction that control downstream [Cac2+]-oscillations. The central theme of this paper is to present the biochemical pathways, as well as molecular mechanisms underlying the GPCR-mediated Ca2+-dynamics in order to facilitate a better understanding of how agonist concentration is encoded in Ca2+-signals for Gαq, Gαs, and Gαi/o signaling pathways. Moreover, we present the GPCR targeting drugs that are relevant for treating cardiac, respiratory, and neuro-diseases. The current paper presents the ODE formulation for various models along with the detailed schematics of signaling networks. To provide a systems perspective, we present the network motifs that can provide readers an insight into the complex and intriguing science of agonist-mediated Ca2+-dynamics. One of the features of this review is to pinpoint the interplay between positive and negative feedback loops that are involved in controlling intracellular [Cac2+]-oscillations. Furthermore, we review several examples of dose-response curves obtained from [Cac2+]-spiking for various GPCR pathways. This paper is expected to be useful for pharmacologists and computational biologists for designing clinical applications of GPCR targeting drugs through modulation of Ca2+-dynamics., Highlights • Biochemical pathways underlying the GPCR mediated control of calcium dynamics. • Network structure and feedback loops present in models for calcium dynamics. • Experimental investigations proving the feedback loops in GPCR signal transduction. • Dose-response curves obtained from agonist mediated Ca2+-spiking. • Agonist concentration encoding in Ca2+ oscillations.

This paper is motivated by the observation that intermediaries play an important role in international trade such that direct trade between producers and consumers is observed alongside indirect trade through intermediaries. A growing body of evidence also documents the importance of information frictions for exporting. The paper examines the matching role of intermediaries through the building of contacts in a market characterised by information frictions. A pairwise matching model with two-sided information asymmetry is developed to analyse the channels through which information costs can affect the pattern of direct and intermediated trade. All traders can match directly through a stochastic matching process but some may match indirectly through an intermediary who invests in establishing a network of contacts. Intermediation is shown to unambiguously raise expected trade volume and welfare by expanding the set of matching technologies available to traders, while convexity in network-building costs with respect to network size gives rise to both direct and indirect trade in equilibrium. The trade pattern depends on the relative responsiveness of the direct and indirect matching technologies to information costs, which for some parameter values generates a non-monotonic relationship between information frictions and trade.

Large-scale electric aircraft is a disruptive technology to address the environmental impact of air travel. Fault current limitation is crucial to realise the safety and reliability of the electric aircraft, in particular for large-scale electric aircraft using DC distribution network. This paper investigates the behavior of the resistive SFCL under different cryogenic cooling systems including liquid nitrogen and helium gas circulation cooling systems for the electric aircraft DC distribution network. Electromagnetic and thermoelectric models were used to predict the characteristics of resistive SFCL. The simulation results demonstrate that it is promising to design resistive SFCL using liquid nitrogen cooling as well as helium gas circulation cooling systems, which offer flexibility for SFCL cryogenic cooling system for electric aircraft applications.

The cerebral vasculature has a complex and hierarchical network, ranging from vessels of a few millimeters to superficial cortical vessels with diameters of a few hundred micrometers, and to the microvasculature (arteriole/venule) and capillary beds in the cortex. In standard imaging techniques, it is difficult to segment all vessels in the network, especially in the case of the human brain. This study proposes a hybrid modeling approach that determines these networks by explicitly segmenting the large vessels from medical images and employing a novel vascular generation algorithm. The framework enables vasculatures to be generated at coarse and fine scales for individual arteries and veins with vascular subregions, following the personalized anatomy of the brain and macroscale vasculatures. In this study, the vascular structures of superficial cortical (pial) vessels before they penetrate the cortex are modeled as a mesoscale vasculature. The validity of the present approach is demonstrated through comparisons with partially observed data from existing measurements of the vessel distributions on the brain surface, pathway fractal features, and vascular territories of the major cerebral arteries. Additionally, this validation provides some biological insights: (i) vascular pathways may form to ensure a reasonable supply of blood to the local surface area; (ii) fractal features of vascular pathways are not sensitive to overall and local brain geometries; and (iii) whole pathways connecting the upstream and downstream entire-scale cerebral circulation are highly dependent on the local curvature of the cerebral sulci., Author summary Cerebral autoregulation in the complex vascular networks of the brain is an amazing achievement. We believe that numerical analysis of the cerebral blood circulation using an anatomically precise vascular model provides a powerful tool for evaluating the direct relationships between local- and global-scale blood flows. However, there is a lack of information about the overall vascular pathways in the human brain, preventing a monolithic model of the human cerebrovasculature from being established. This paper presents a multiscale model of human cerebrovasculature based on a hybrid approach that uses image-based geometries and a newly developed mathematical algorithm. One important argument of this paper is the validity of the cerebrovasculature represented in the model, which reflects anatomical features of major cerebral vasculatures and brain shape, and has strong similarities with available data for human superficial cortical vessels. Investigations of the reconstructed model allow us to derive some biological insights and associated hypotheses for the cerebral vasculature. The authors believe the present cerebrovascular model can be applied to numerical simulations of the entire-scale cerebral blood flow.

California has a range of existing and proposed targets toward a low carbon future. This paper summarizes an analytical review, focused on modeling approaches and what is known about their feasibility and cost. The findings in this paper are based on the Climate Change Policy Modeling (CCPM) forum, which included modelers, policy makers and stakeholders evaluating targets and pathways to low-carbon futures and identifying required policies to achieve goals. The third forum, CCPM-3, was on May 14th, 2018, at the University of California, Davis and provided critical discussion and a gathering of the key experts in this topic area This report builds on the findings of CCPM and integrates with other literature where possible. It includes a review of the CO2-relevant targets, discussion of studies and modeling efforts to assess meeting such targets, including feasibility and cost. This includes analysis in the transportation and energy sectors, as well as land use and carbon sequestration.

Clinical trials covering the immunogenicity of a vaccine aim to study the longitudinal dynamics of certain immune cells after vaccination. The corresponding immunogenicity datasets are mainly analyzed by the use of statistical (mixed effects) models. This paper proposes the use of mathematical ordinary differential equation (ODE) models, combined with a mixed effects approach. ODE models are capable of translating underlying immunological post vaccination processes into mathematical formulas thereby enabling a testable data analysis. Mixed models include both population-averaged parameters (fixed effects) and individual-specific parameters (random effects) for dealing with inter- and intra-individual variability, respectively. This paper models B-cell and T-cell datasets of a phase I/II, open-label, randomized, parallel-group study (NCT00492648) in which the immunogenicity of a new Herpes Zoster vaccine (Shingrix) is compared with the original Varicella Zoster Virus vaccine (Varilrix). Since few significant correlations were found between the B-cell and T-cell datasets, each dataset was modeled separately. By following a general approach to both the formulation of several different models and the procedure of selecting the most suitable model, we were able to propose a mathematical ODE mixed-effects model for each dataset. As such, the use of ODE-based mixed effects models offers a suitable framework for handling longitudinal vaccine immunogenicity data. Moreover, this approach allows testing for differences in immunological processes between vaccines or schedules. We found that the Shingrix vaccination schedule led to a more pronounced proliferation of T-cells, without a difference in T-cell decay rate compared to the Varilrix vaccination schedule. (C) 2019 Elsevier Ltd. All rights reserved. This research was funded by the University of Antwerp [BOF Concerted Research Action, Methusalem funding], NH acknowledges support from the chair in evidence-based vaccinology sponsored by a gift from Pfizer (2009-2018) and GSK (2016) and from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement 682540 - TransMID). This research was supported by the Antwerp Study Centre for Infectious Diseases (BID). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Robust measurement planning algorithms and calibration protocols applicable to both serial and hybrid industrial robots containing four-bar actuating mechanisms are presented in this paper. Contrary to currently available approaches developed by commercial calibration solutions providers, the present methodology based on a Laser Interferometry tracking system leads to an unprecedented level of positional accuracy, as required in typical aerospace manufacturing robotic applications. This paper presents several technical contributions, from innovative measurement planning algorithms, highly accurate geometric and nongeometric kinematic errors models to functional software modules incorporated in state-of-the-art robotic off-line programming software, viz, Workspace5.04 and Delmia V5 Robotics. The improvement in robot accuracy achieved via this complete suite of measurement algorithms and software tools is finally demonstrated through test cases., SAE 2004 Aerospace Manufacturing & Automated Fastening Conference & Exhibition, September 20-23, 2004, St-Louis, United States

The paper presents an overview of the final results of the 7FP ICT-EMISSIONS project that developed and validated a novel methodology and tool set to evaluate the impact of ICT-related transport measures on mobility and CO2 emissions of vehicle fleets under real-world conditions. The methodology combines traffic and emission modelling at micro and macro scales. The integration of these scales is an important feature because a measure to influence the behaviour of single vehicles may have an impact on the whole network, while traffic management at the network level may influence the behaviour of the single vehicles. The paper presents results of a number of ITS systems including Variable Speed Limit (VSL), Green Navigation (GN), Urban Traffic Control (UTC), Ecodriving and Adaptive Cruise Control Systems (ACC). These measures have been tested for concrete application cases implemented in the cities of Turin, Madrid and Rome. Starting point were real-world data collected by means of floating cars. The investigations have taken into account different penetration rates of ICT measures, as well as different traffic conditions (e.g. free flow, congested). Each case has been modelled for the current and at least on future fleet composition. The results indicate that ITS are overall able to contribute to CO2 emissions reduction by several percent points; the effects, nevertheless, are different depending on local conditions. The CO2 benefit is also found to be constrained by the penetration rates of the on-road ITS equipped vehicles: as this share increases a maximum is reached at up to 50% penetration rate and under non-congested conditions.

This paper introduces a time-since-recovery structured, multi-strain, multi-population model of avian influenza. Influenza A viruses infect many species of wild and domestic birds and are classified into two groups based on their ability to cause disease: low pathogenic avian influenza (LPAI) and high pathogenic avian influenza (HPAI). Prior infection with LPAI provides partial immunity towards HPAI. The model introduced in this paper structures LPAI-recovered birds (wild and domestic) with time-since-recovery and includes cross-immunity towards HPAI that can fade with time. The model has a unique disease-free equilibrium (DFE), unique LPAI-only and HPAI-only equilibria and at least one coexistence equilibrium. We compute the reproduction numbers of LPAI ( $ {\mathcal R}_{\rm L} $ ) and HPAI ( $ {\mathcal R}_{\rm H} $ ) and show that the DFE is locally asymptotically stable when $ {\mathcal R}_{\rm L} 1 $ ( $ {\mathcal R}_{\rm H} >1 $ ) and it is locally asymptotically stable if HPAI (LPAI) cannot invade the equilibrium, that is, if the invasion number $ \hat {\mathcal {R}}_{\rm L}^{\rm H}

Influenza A virus (IAV) infection represents a global threat causing seasonal outbreaks and pandemics. Additionally, secondary bacterial infections, caused mainly by Streptococcus pneumoniae, are one of the main complications and responsible for the enhanced morbidity and mortality associated with IAV infections. In spite of the significant advances in our knowledge of IAV infections, holistic comprehension of the interplay between IAV and the host immune response (IR) remains largely fragmented. During the last decade, mathematical modeling has been instrumental to explain and quantify IAV dynamics. In this paper, we review not only the state of the art of mathematical models of IAV infection but also the methodologies exploited for parameter estimation. We focus on the adaptive IR control of IAV infection and the possible mechanisms that could promote a secondary bacterial coinfection. To exemplify IAV dynamics and identifiability issues, a mathematical model to explain the interactions between adaptive IR and IAV infection is considered. Furthermore, in this paper we propose a roadmap for future influenza research. The development of a mathematical modeling framework with a secondary bacterial coinfection, immunosenescence, host genetic factors and responsiveness to vaccination will be pivotal to advance IAV infection understanding and treatment optimization.

This note first summarizes the history of the manuscript "On a Continuum Model for Avalanche Flow and Its Simplified Variants" by Grigorian and Ostroumov―published in the Special Issue on snow avalanche dynamics of Geosciences―since the early 1990s and explains the guiding principles in editing it for publication. The changes are then detailed and some explanatory notes given for the benefit of readers who are not familiar with the early Russian work on snow avalanche dynamics. Finally, the editor's personal views as to why he still considers this paper of relevance for avalanche dynamics research today are presented in brief essays on key aspects of the paper, namely the role of simple and complex models in avalanche research and mitigation work, the status and possible applications of Grigorian's stress-limited friction law, and non-monotonicity of the dynamics of the Grigorian–Ostroumov model in the friction coefficient. A comparison of the erosion model proposed by those authors with two other models suggests to enhance it with an additional equation for the balance of tangential momentum across the shock front. A preliminary analysis indicates that continuous scouring entrainment is possible only in a restricted parameter range and that there is a second erosion regime with delayed entrainment.

The increasing penetration of renewables in power systems reconfigures the generation mix and geography distribution, resulting in more frequent power flow congestion. Conventionally, a relatively conservative dispatch margin for transmission congestion in network constraints was reserved to ensure safe operation due to potential deviations introduced by DC power flow modeling and conservative line rating. This paper proposes a real-time power market clearing model with improved network constraints considering power transfer distribution factor (PTDF) correction and fast-calculated dynamic line rating. The clearing model based on PTDF correction is proposed first employing the Taylor expansion with the voltage and phase angle approximation. An improved dynamic line rating model is further applied into the clearing model based on the piecewise linear approximation method, which calculates real-time conductor temperature faster with sufficient precision. We test and verify the validity of the proposed model based on three independent systems including the IEEE 39-bus system, the IEEE 2383-bus system, and the real power grid system in Yunnan province of China, respectively. The results show that the improved clearing model reduces the calculated power flow deviation between the clearing results and real conditions compared with traditional security constraints, where the efficiency of power grid operation is also increased.

© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works This paper proposes an optimization-based size reduction methodology for Modular Multilevel Converters (MMC), focusing on minimizing the converter's sub-module capacitor CSM. The analysis is performed considering both the converter's current and voltage limitations and the Transmission System Operator (TSO) Fault Ride Through (FRT) requirements. By means of a steady-state analysis, the time-domain expressions of the converter's arms energies are obtained and their behavior throughout the MMC's operating range is shown. Based on these expressions, the optimization-based problem to reduce the CSM size is developed and its constraints are imposed to ensure that the converter's voltage and current levels are within its design limitations. The suggested method is compared with different approaches for distinct active and reactive power set-points, where it is shown that the SM capacitor size can be reduced up to 24% in comparison with the method with worst performance and up to 7% regarding the best method used for comparison purposes. Furthermore, time-domain simulations of the MMC considering several AC voltage sags are performed in order to demonstrate that the dynamics of the SM capacitor and the arm applied voltages are within acceptable margins during the different operations.

Cyber-physical system security for electric distribution systems is critical. In direct switching attacks, often coordinated, attackers seek to toggle remote-controlled switches in the distribution network. Due to the typically radial operation, certain configurations may lead to outages and/or voltage violations. Existing optimization methods that model the interactions between the attacker and the power system operator (defender) assume knowledge of the attacker's parameters. This reduces their usability. Furthermore, the trend with coordinated cyberattack detection has been the use of centralized mechanisms, correlating data from dispersed security systems. This can be prone to single point failures. In this paper, novel mathematical models are presented for the attacker and the defender. The models do not assume any knowledge of the attacker's parameters by the defender. Instead, a machine learning (ML) technique implemented by a multi-agent system correlates detected attacks in a decentralized manner, predicting the targets of the attacker. Furthermore, agents learn optimal mitigation of the communication level through Q-learning. The learned attacker motive is also used by the defender to determine a new configuration of the distribution network. Simulations of the technique have been performed using the IEEE 123-Node Test Feeder. The simulation results validate the capability and performance of the algorithm. U.S. National Science Foundation [1837359]; Commonwealth Cyber Initiative (CCI), State of Virginia [PR6ZBSTA, 5GPG] Published version This work was supported in part by the U.S. National Science Foundation under Grant 1837359; and in part by the projects under Grant PR6ZBSTA and Grant 5GPG sponsored by Commonwealth Cyber Initiative (CCI), State of Virginia.

This is the accepted manuscript of the paper "Modeling the dispersion of viable and total Escherichia coli cells in the artificial semi-enclosed bathing area of Santa Marinella (Latium, Italy)", published as final paper in "Marine Pollution Bulletin 95 (2015) 141–154;https://doi.org/10.1016/j.marpolbul.2015.04.030" Bonamano S, Madonia A, Borsellino C, Stefanì C, Caruso G, De Pasquale F, Piermattei V, Zappalà G, Marcelli M (2015). Modeling the dispersion of viable and total Escherichia coli cells in the artificial semi-enclosed bathing area of Santa Marinella (Latium, Italy). MARINE POLLUTION BULLETIN, ISSN: 0025-326X, doi: 10.1016/j.marpolbul.2015.04.030. Coastal areas are strongly affected by episodes of fecal contamination due to polluted water inflows from inadequately treated sewages. The present study aims to investigate the dispersion of Escherichia coli in the artificial semi-enclosed bathing area of Santa Marinella (Latium, Italy) through in situ samplings carried out in summer 2012 and the application of a dynamic model. Collected samples were analyzed by the Culture-Based technique and the Fluorescent Antibody method in order to estimate both the viable culturable cells and the total E. coli population, respectively. The in situ datasets were used to test the proposed modeling approach and simulate the behavior of bacteria as particles subjected, or not, to decay. Next, the flushing time and the computation of the Microbiological Potential Risk Area allowed the evaluation of the contribution of physical and biological processes to coliform dispersion and the related potential risk for bathers.

In business replenishment, discount offers of multi-item may either provide different discount schedules with a single discount type, or provide schedules with multiple discount types. The paper investigates the joint effects of multiple discount schemes on the decisions of multi-item joint replenishment. In this paper, a joint replenishment problem (JRP) model, considering three discount (all-unit discount, incremental discount, total volume discount) offers simultaneously, is constructed to determine the basic cycle time and joint replenishment frequencies of multi-item. To solve the proposed problem, a heuristic algorithm is proposed to find the optimal solutions and the corresponding total cost of the JRP model. Numerical experiment is performed to test the algorithm and the computational results of JRPs under different discount combinations show different significance in the replenishment cost reduction.

Passive photonic integrated circuits (PICs) can be easily characterized in the frequency-domain, but their accurate time-domain performance evaluation is a hurdle for system-level designers, especially when dealing with resonant circuits having highly dispersive behavior, such as ring resonators. In this paper, a new equivalent circuit modeling and simulation approach is proposed, based on the Complex Vector Fitting algorithm, able to perform accurate and robust time-domain simulations of passive PICs directly in standard SPICE simulators. The proposed modeling technique starts from scattering parameters of passive PICs, and is able to capture linear and high order dispersion, backscattering, and wavelength dependent effects. Considering the different nature of optical and electronic signals, a novel concept of equivalent voltage and current for optical waveguides is proposed to simplify the optical to electronic ports conversion and to make it possible to connect and terminate the equivalent circuit models as needed in SPICE simulators, natively supporting bidirectional signal propagation in a waveguide. This work provides a precise and reliable solution to evaluate time-domain characteristics of passive PICs and to access any internal nodes within a circuit, such as the signals inside a ring resonator. Three examples of time-domain simulations of passive PICs in commercial SPICE simulators are presented to demonstrate the flexibility and advantages of the proposed technique.

Classifying bank accounts by using transaction data is encouraging in cracking down on illegal financial activities. However, few research simultaneously use heterogenous features, which are embedded in the time series data. In this paper, a two route convolution neural network TRHD-CNN model, fed with two types of heterogeneous feature matrices, is proposed for classifying the bank accounts. TRHD-CNN adopts divide and conquer strategy to extract characteristics from two types of data source independently. The strategy is proved able in mining complementary classification characteristics. We firstly transfer the original log data into a directed and dynamic transaction network. On the basis of that, two feature generation methods are devised for extracting information from local topological structure and time series transaction respectively. A DirectedWalk method is developed in this paper to learning the network vector of vertices used for embedding the neighbor relationship of bank account. The extensive experimental results, conducted on a real bank transaction dataset that contains illegal pyramid selling accounts, show the significant advantage of TRHD-CNN over the existing methods. TRHD-CNN can provide recall scores up to 5.15% higher than competing methods. In addition, the two-route architecture of TRHD-CNN is easy to extend to multi-route scenarios and other fields.

The scrap dissolution in an actual process like the BOF is affected both by mass transfer and heat transfer. In this paper, the mass transfer of carbon in liquid melt is considered along with heat transfer. The approaches used in this paper to model the scrap dissolution phenomenon include the application of Green's function, quasi-static, integral profile, and the finite difference approach for different Biot numbers. Mass transfer coefficients are calculated using the Chilton-Colburn's analogy for the case of forced convection. Since the quasi-static approach requires the least computational time, it is used for a detailed parametric study, including the effect of other parameters like different scrap ratios and heating rates of liquid melt. The region of control of heat transfer vs mass transfer is also identified. The dissolution of mixed scrap (light and heavy scrap) is investigated for different scrap ratios and the autogenous heating rates of liquid melt, with the help of mathematical models. The heat transfer coefficient is estimated as a function of mixing energy and the mass transfer coefficient by invoking the Chilton-Colburn analogy. The permissible limits of light scrap, which can be charged into the BOF, are also suggested from the results of this model. The Artificial Neural Network (ANN) model is trained on the dataset (patterns) generated by the coupled heat and mass transfer model. The accuracy of the results obtained using different ANN topologies is discussed followed by a recommendation for selecting the best approach. � 2013 The Minerals, Metals & Materials Society and ASM International.

With the development of computer network bandwidth, packet classification algorithms which are able to deal with large-scale rule sets are in urgent need. Among the existing algorithms, researches on packet classification algorithms based on hierarchical trie have become an important packet classification research branch because of their widely practical use. Although hierarchical trie is beneficial to save large storage space, it has several shortcomings such as the existence of backtracking and empty nodes. This paper proposes a new packet classification algorithm, Hierarchical Trie Algorithm Based on Expectation-Maximization Clustering (HTEMC). Firstly, this paper uses the formalization method to deal with the packet classification problem by means of mapping the rules and data packets into a two-dimensional space. Secondly, this paper uses expectation-maximization algorithm to cluster the rules based on their aggregate characteristics, and thereby diversified clusters are formed. Thirdly, this paper proposes a hierarchical trie based on the results of expectation-maximization clustering. Finally, this paper respectively conducts simulation experiments and real-environment experiments to compare the performances of our algorithm with other typical algorithms, and analyzes the results of the experiments. The hierarchical trie structure in our algorithm not only adopts trie path compression to eliminate backtracking, but also solves the problem of low efficiency of trie updates, which greatly improves the performance of the algorithm.

This paper presents a novel method on the optimization of bi-objective Flexible Job-shop Scheduling Problem (FJSP) under stochastic processing times. The robust counterpart model and the Non-dominated Sorting Genetic Algorithm II (NSGA-II) are used to solve the bi-objective FJSP with consideration of the completion time and the total energy consumption under stochastic processing times. The case study on GM Corporation verifies that the NSGA-II used in this paper is effective and has advantages to solve the proposed model comparing with HPSO and PSO+SA. The idea and method of the paper can be generalized widely in the manufacturing industry, because it can reduce the energy consumption of the energy-intensive manufacturing enterprise with less investment when the new approach is applied in existing systems.

[eng] In this thesis I investigated the status of the Mediterranean Sea ecosystem and the sustainability of its marine resources using an interdisciplinary approach, which combined data integration and modelling approaches. Results highlighted a series of commonalities for Mediterranean marine ecosystems: they indicate that ‘small pelagic fishes’, mainly European pilchards and anchovies, both with high biomasses and high proportions in catches, are important structuring species for the Mediterranean ecosystem (at regional, sub-regional and local scales). ‘Large pelagic fishes’ are the main keystone species for both the past and current Mediterranean ecosystem configuration, while ‘sharks’ and ‘medium pelagic fishes’ played a key role in the past, but their ecological role is currently replaced by benthopelagic and benthic cephalopods. In addition, the ‘Mediterranean monk seal’ “Monachus monachus”, where it still occurs, is the species with the highest TL followed by ‘piscivorous cetaceans’ and ‘large pelagic fish’. Looking at temporal ecosystem dynamics, biomass trends and ecological indicators (e.g., community biomass, trophic levels of the community, catch and diversity indicators) reveal that the combined effect of excessive fishing pressure and changes in primary productivity altered the Mediterranean marine ecosystem over time, especially reducing the proportions of top predators (e.g., pinnipeds, large pelagic fish) and mid trophic level organisms (e.g., small pelagic fishes) and increasing the abundance of groups at lower trophic levels (e.g., invertebrates). The Western and the Adriatic Seas are the most degraded ecosystems with biomasses declines among all the species compartments assessed (from forage fish to sharks/rays and skates, except for invertebrates that remained stable in time). The Ionian Sea was found to be the area with less biomass changes historically in comparison with available survey data. Even at a more local scale (Amvrakikos Gulf), both ecological indicators and biomass trends highlight a degradation of the demersal compartments of the food web but a relative stability of the pelagic ones mainly due to high eutrophication levels. Fishing pressure and changes in primary production (PP) play an important role in driving species temporal dynamics; yet, PP seems to be the strongest driver upon the Mediterranean Sea ecosystem. Fisheries data (mainly catch and effort) are found to be under-reported and under-estimated at regional, sub-regional and local scale. For example, fishing mortalities (and so landings data obtained from Food and Agriculture Organization [FAO] fisheries statistics) of three most important commercial species (European pilchard ‘Sardina pilchardus’, anchovy ‘Engraulis encrasicolus’ and hake ‘Merluccius merluccius’) were in fact observed in early decades (1950s), in all the Mediterranean sub-regions, between 5 and 10 times inferior from the average reference values reported in stock assessment for these fish stocks in the Mediterranean Sea. Even in the assessment of the Italian fisheries, the reconstructed of total catches were 2.6 times the landings officially reported by the FAO on behalf of Italy for the same period and same area, with unreported commercial landings (from both industrial and artisanal sectors) contributing 50% to the total catch (in relation to FAO reporting) and discards contributing another 7%. In Europe, several models and associated indicators exist that could be used in support of European policies (MSFD); yet, Ecopath with Ecosim (EwE) is the most applied tool for modelling marine and aquatic ecosystems and the one that can produce the largest number of indicators useful for the Marine Strategy Framework Directive (MSFD). Since anthropogenic pressures are rapidly expanding in the basin, this work constitutes an important first step to advance further in the regional assessment of the Mediterranean Sea ecosystem and to inform conservation plans and management actions., [cat] En aquesta tesi he investigat l'estat ambiental del mar mediterrani i la sostenibilitat dels seus recursos marins mitjançant un enfoc interdisciplinari que combina la integració de dades i la modelització d'ecosistemes. Els resultats posen en relleu una sèrie de punts en comú dels ecosistemes marins mediterranis: el grup de "peixos pelàgics de mida petita", principalment compost per sardines i seitons, amb grans biomasses i captures, és un grup important en relació amb l'estructura de l'ecosistema mediterrani (tant a nivell regional, sub regional i a escales locals). El grup de “peixos pelàgics de gran mida” destaca per ser important com a grup clau de l'ecosistema, tant en el passat com en el present, mentre que el grup dels “taurons” i “peixos pelàgics de mida mitjana” han jugat un paper ecològic clau en el passat, però aquest és actualment reemplaçat pels grups de peixos bentopelàgicos i cefalòpodes bentònics. A més, el vell marí del mediterrani “Monachus monachus”, en aquelles zones on encara existeix, és l'espècie amb el nivell tròfic més alt, seguida pel grup de "cetacis que s'alimenten de peixos" i "peixos pelàgics de grans dimensions". Pel que fa a la dinàmica temporal de l'ecosistema, les tendències de la biomassa i dels indicadors ecològics (per exemple, la biomassa de la comunitat, els nivells tròfics de la comunitat, les captures i els indicadors de diversitat) revelen que l'efecte combinat d’una pressió pesquera excessiva i els canvis en la productivitat primària ha alterat l'ecosistema marí mediterrani a través del temps, especialment pel que fa a una reducció de les proporcions dels depredadors superiors (per exemple, pinnípedes, i peixos pelàgics de grans dimensions) i organismes de nivells tròfics mitjans (per exemple, peixos pelàgics de mida petita), i l'augment en abundància de grups d'organismes en nivells tròfics inferiors (per exemple, invertebrats). El mar mediterrani occidental i el mar adriàtic són els ecosistemes més degradats amb baixades de biomasses per a totes les espècies avaluades (des dels peixos pelàgics de mida petita als taurons i ratjades, amb excepció dels invertebrats que es mantenen estables en el temps). El mar jònic és l'àrea amb menys canvis històrics en termes de biomassa en comparació amb les dades disponibles de mostrejos. Fins i tot a una escala més local (en el Golf de Amvrakikos), tant els indicadors ecològics com les biomasses evidencien una degradació dels compartiments demersals de la xarxa tròfica, encara que s'observa una relativa estabilitat dels compartiments pelàgics, principalment a causa dels alts nivells d'eutrofització. La pressió pesquera elevada i els canvis en la producció primària (PP) juguen un paper important en la dinàmica temporal de les espècies; però, els canvis en la PP semblen ser els principals impulsors de la dinàmica temporal de l'ecosistema del mar mediterrani. Les dades pesquers (principalment la captura i l'esforç pesquer) es troben subestimats i conseqüentment registrats de forma errònia a escala regional, sub regional i local. Per exemple, la mortalitat per pesca (i per tant les dades de desembarcament que s'obtenen de les estadístiques de pesca de l'Organització per a l'Agricultura i l'Alimentació [FAO]) de tres de les espècies comercials més importants (Sardina europea “Sardina pilchardus”, anxova “Engraulis encrasicolus” i lluç “Merluccius merluccius”) per a les primeres dècades d'aquest estudi (1950), i en totes les sub regions mediterrànies analitzades, era entre 5 i 10 vegades inferior als valors de referència mitjana registrats en avaluacions de l'estoc d'aquestes poblacions al mar mediterrani. Fins i tot en l'avaluació de les pesqueries italianes, la reconstrucció de les captures totals mostra que les captures totals són 2,6 vegades més grans que els desembarcaments registrats oficialment per la FAO durant el mateix període i per la mateixa zona, amb desembarcaments comercials no declarats (dels sectors industrials i artesanals) que contribueixen al 50% de la captura total (en relació als informes de la FAO) i els descarts que contribueixen un altre 7%. A Europa hi ha diversos models i indicadors associats que podrien ser utilitzats en suport de les polítiques europees de gestió mediambiental, com la Directiva Marc sobre l'Estratègia Marina (MSFD); de totes formes, Ecopath with Ecosim (EwE) és l'eina més aplicada per a la modelització dels ecosistemes marins i aquàtics i la que pot produir un major nombre d'indicadors útils per a la MSFD. Atès que les pressions antropogèniques s'estan expandint ràpidament a la conca mediterrània, aquest treball constitueix un primer pas important per avançar en l'avaluació regional de l'estat ambiental de l'ecosistema marí mediterrani i per informar els plans de conservació i gestió presents i futurs.

In this paper, the issue of nonlinear sensitivity analysis for dimensionality reduction in hydrologic model calibration is discussed, and a novel method to quantify the sensitivity of each parameter that considers the nonlinear relationship in the model is presented. The method is based on computing the absolute variation of the nonlinear function represented by the model in its parameter space. The paper discusses the theoretical background of the method and presents the algorithm. The algorithm employs neural network as a pseudo simulator to reduce the computational burden of the analysis. The proposed approach of sensitivity analysis is illustrated through a case study on a physically based distributed hydrologic model. The results indicate that the method is able to rank the parameters effectively, and the ranking can be interpreted in the context of the physical processes being considered by the model. � 2010 Elsevier Ltd.

This paper proposes a new deep learning (DL) based model-free robust method for bulk system on-line load restoration with high penetration of wind power. Inspired by the iterative calculation of the two-stage robust load restoration model, the deep neural network (DNN) and deep convolutional neural network (CNN) are respectively designed to find the worst-case system condition of a load pickup decision and evaluate the corresponding security. In order to find the optimal result within a limited number of checks, a load pickup checklist generation (LPCG) algorithm is developed to ensure the optimality. Then, the fast robust load restoration strategy acquisition is achieved based on the de-signed one-line strategy generation (OSG) algorithm. The pro-posed method finds the optimal result in a model-free way, holds the robustness to handle uncertainties, and provides real-time computation. It can completely replace conventional robust optimization and supports on-line robust load restoration which better satisfies the changeable restoration process. The effectiveness of the proposed method is validated using the IEEE 30-bus system and the IEEE 118-bus system, showing high computational efficiency and considerable accuracy.