Dynamic Model of WSN

The principal concerns in driving safety with standard vehicles or cybercars are understanding and preventing risky situations. A close examination of accident data reveals that losing control of the vehicle is the main reason for most car accidents. To help to prevent such accidents, vehicle-control systems may be used, which require certain input data concerning vehicledynamic parameters and vehicle-road interaction. Unfortunately, some fundamental parameters, like tire-road forces and sideslip angle are difficult to measure in a car, for both technical and economic reasons. Therefore, this study presents a dynamic modeling and observation method to estimate these variables. One of the major contributions of this study, with respect to our previous work and to the largest literature in the field of the lateral dynamic estimation, is the fact that lateral tire force at each wheel is discussed in details. To address system nonlinearities and unmodeled dynamics, two observers derived from extended and unscented Kalman filtering techniques are proposed and compared. The estimation process method is based on the dynamic response of a vehicle instrumented with available and potentially integrable sensors. Performances are tested using an experimental car. Experimental results demonstrate the ability of this approach to provide accurate estimations, and show its practical potential as a low-cost solution for calculating lateral tire forces and sideslip angle.

We show that states of a dynamical system can be usefully represented by multi-step, action-conditional predictions of future observations. State representations that are grounded in data in this way may be easier to learn, generalize better, and be less dependent on accurate prior models than, for example, POMDP state representations. Building on prior work by Jaeger and by Rivest and Schapire, in this paper we compare and contrast a linear specialization of the predictive approach with the state representations used in POMDPs and in k-order Markov models. Ours is the first specific formulation of the predictive idea that includes both stochasticity and actions (controls). We show that any system has a linear predictive state representation with number of predictions less than or equal to the number of states in its minimal POMDP model.

We consider a one-dimensional dynamic model that describes the evolution of damage caused by tension in a viscoelastic material. The process is modeled by a coupled set of two differential inclusions for the elastic displacement and damage fields. We establish the existence of local weak solutions. The existence result is derived from the a priori estimates obtained for a sequence of regularized, truncated, and time-retarded approximations. We also establish the existence of the unique weak solution of a simplified version of the model.

In this paper we illustrate the properties and the morphology of a human like neural reflex controller, used to set the stiness and joint positions of an anthropomorphic artificial hand. In particular we explain, by simulations results, its ability to emulate the myotatic human reflex, and its capacity to learn in real time the best control strategy. We also present

This paper proposes a new type of jetting dispenser driven by a piezostack actuator. After describing structural components of the dispensing mechanism and operating principle, a dynamic model of the dispenser is analytically formulated by considering dynamic behaviors of the piezostack-piston head and the ball-needle. The inelastic impact between the ball-needle and the ball-seat during dispensing process is also considered in the modeling. An analytical fluid-solid interaction model is then derived by integrating the dynamic behavior of the dispensing fluid. Dispensing performances such as dot size and flow rate are evaluated under various frequencies and amplitudes of the sinusoidal driving voltage applied to the piezostack actuator.

Gene regulatory network is a collection of DNA which interact with each other and with other matter in the cell. The lac operon is an example of a relatively simple genetic network and is one of the best-studied structures in the Escherichia coli bacteria. In this work we consider a deterministic model of the lac operon with a noise term, representing the stochastic nature of the regulation. The model is written in terms of a system of simultaneous first order differential equations with delays. We investigate an analytical and numerical solution and analyse the range of values for the parameters corresponding to a stable solution.

Environmental modelling languages provide the possibility to construct models in two or three spatial dimensions. These models can be static models, without a time component, or dynamic models. Dynamic models are simulations run forward in time, where the state of the model at time t is defined as a function of its state in a period or time step preceding t. Since inputs and parameters of environmental models are associated with errors, environmental modelling languages need to provide techniques to calculate how these errors propagate to the output(s) of the model. Since these techniques are not yet available, the paper describes concepts for extending an environmental-modelling language with functionality for error-propagation modelling. The approach models errors in inputs and parameters as stochastic variables, while the error in the model outputs is approximated with a Monte Carlo simulation. A modelling language is proposed which combines standard functions in a structured script (program) for building environmental models, and calculation of error propagation in these models. A prototype implementation of the language is used in three example models to illustrate the concepts.

... Firm investment in imperfect capital markets: A structural estimation. Sangeeta Pratap Corresponding Author Contact Information , E-mail The Corresponding Author , a and Sílvio Rendon E-mail The Corresponding Author , b. ... Agency costs, net worth, and business fluctuations. ...

This paper describes an attempt to model soil moisture over the Australian continent with an integrated system of dynamic models and a Geographic Information System (GIS) data base. A land surface scheme with improved treatment of soil hydrological processes is described. The non-linear relationships between soil hydraulic conductivity, matric potential and soil moisture are derived from the Broadbridge and White soil model. For a single location, the prediction of the scheme is in good agreement with the measurements of the Hydrological and Atmospheric Pilot Experiment (HAPEX). High resolution atmospheric and geographic data are used in soil moisture prediction over the Australian continent. The importance of reliable land surface parameters is emphasized and details are given for deriving the parameters from a GIS. Predicted soil moisture patterns over the Australian continent in summer, with a 50 km spatial resolution, are found to be closely related to the distribution of soil types, apart from isolated areas and times under the influence of precipitation. This is consistent with the notion that the Australian continent in summer is generally under water stress. In contrast, predicted soil temperatures are more closely related to radiation patterns and changes in atmospheric circulation. The simulation can provide details of soil moisture evolution both in space and time, that are very useful for studies of land use sustainability, such as plant growth modelling and soil erosion prediction.

In this paper, we present a system that estimates and visualizes muscle tensions in real time using optical motion capture and electromyography (EMG). The system overlays rendered musculoskeletal human model on top of a live video image of the subject. The subject therefore has an impression that he/she sees the muscles with tension information through the cloth and skin. The main technical challenge lies in real-time estimation of muscle tension. Since existing algorithms using mathematical optimization to distribute joint torques to muscle tensions are too slow for our purpose, we develop a new algorithm that computes a reasonable approximation of muscle tensions based on the internal connections between muscles known as neuronal binding. The algorithm can estimate the tensions of 274 muscles in only 16 ms, and the whole visualization system runs at about 15 fps. The developed system is applied to assisting sport training, and the user case studies show its usefulness. Possible applications include interfaces for assisting rehabilitation.

A central puzzle for theories of choice is that people's preferences between options can be reversed by the presence of decoy options (that are not chosen) or by the presence of other irrelevant options added to the choice set. Three types of reversal effect reported in the decision-making literature, the attraction, compromise, and similarity effects, have been explained by a number of theoretical proposals. Yet a major theoretical challenge is capturing all 3 effects simultaneously. We review the range of mechanisms that have been proposed to account for decoy effects and analyze in detail 2 computational models, decision field theory (Roe, Busemeyer, & Townsend, 2001) and leaky competing accumulators (Usher & McClelland, 2004), that aim to combine several such mechanisms into an integrated account. By simulating the models, we examine differences in the ways the decoy effects are predicted. We argue that the LCA framework, which follows on Tversky's relational evaluation with loss aversion (Tversky & Kahneman, 1991), provides a more robust account, suggesting that common mechanisms are involved in both high-level decision making and perceptual choice, for which LCA was originally developed.

Freeze drying process involves the following three stages: freezing, primary drying and secondary drying stages. A theoretical model was developed and solved in order to describe quantitatively the dynamic behavior of the primary and secondary drying stages. The solution procedure involves the discretization of the equations by orthogonal collocation in the axial direction and the integration, in relation, to time by differential integrator (LSODE). For the validation procedure, the results of the solution model were compared real values. The model allows seeing design and operating variables more significantly impact the system behavior. Furthermore, the intention was to simulate the process aiming high quality dried product with the minimum time process. The results show that the proposed model presents better predictions than the existing mathematical model, since a more detailed process description is provided.

This paper presents a control strategy for the coordination of multiple mobile robots. A combination of the virtual structure and path following approaches is used to derive the formation architecture. A formation controller is proposed for the kinematic model of two-degree-of-freedom unicycle-type mobile robots. The approach is then extended to consider the formation controller by taking into account the physical

The need for Social Security Reform in the next years is hardly a matter of debate. Therefore, the widespread believe among Americans that Social Security will not be able to pay benefits in the long run at the level that was anticipated, does not come as a surprise. The government acknowledges the situation, and predicts that substantial benefits cuts will be necessary, yet no legislation has been passed to tackle the problem. Researchers, however, have rarely modeled the uncertainty over Social Security reform and benefit levels, and how they affect claiming behavior and retirement. The purpose of this paper is to assess the extent to which these perceptions of future cuts might explain the puzzle of earlier take-up despite bigger penalties to doing so in the presence of increasing longevity. By introducing a small amount of uncertainty (based on selfreported responses to questions regarding expectations over future cuts) of a relatively small cut (compared with what the government reports as necessary to solve the crisis) in a dynamic life-cycle model of retirement, we are able to match the claiming behavior observed in the data, without relying on heterogeneous preferences. Our results support the hypothesis that expectations over future benefits are affecting current behavior. We find that a mis-specified dynamic retirement model would erroneously predict that an increase in the NRA would delay claiming behavior and increase labor supply at older ages. Once the appropriate earnings test incentives are modeled, and we account for the probability of reforms to the system, an increase in the NRA has little effect on claiming behavior, and it can even increase the proportion of individuals claiming before the NRA.

Space operations require high reliability of the inertial navigation system (INS). Therefore, inertial sensors can be used to detect the fault status and then isolate the faulty sensor when possible. In this paper five inertial sensors (gyros) in a pentad geometrical configuration were used to perform the fault detection and isolation (FDI) technique applied to a simplified dynamic model of the Brazilian satellite launch vehicle (VLS).

Abstruct-Carrier transport plays an important role and can significantly affect the ultra-fast properties of quantum-well (QW) lasers. We present a detailed multi-mode time-domain large-signal dynamic model including the effects of carrier transport, suitable for the high-speed QW lasers. It is based on the well-proven transmission-line laser modelling technique with the addition of a multilevel system of coupled rateequations. Simulated results from studies of both the static and small-signal properties are compared with measurements from another laboratory. Our model can accurately predict the modulation-bandwidth discontinuity in QW laser structures with large separate-confinement-heterostructure (SCH) regions. We use large-signal simulations to predict increased damping of transient responses and larger turn-on delays caused by the effects of carrier transport. Our large-signal simulations also show that an increase in the turn-on delay times is expected in QW structures with large carrier transport times across the SCH region, whereas the inter-well transport times do not affect the turn-on delay times significantly. 1077-26013/95$04.00 0 1995 IEEE

The impacts of the 30 active substances, most used in Costa Rica (reference year 1998), are evaluated using two models originally developed to support comparative assertions in the context of the life cycle assessment: the multimedia fate, exposure and effect model Impact Assessment of Chemical Toxics 2002 (IMPACT 2002), and the Dynamic Model for Pesticides Residues in Plants. Results show that only five active substances -namely diazinon, mancozeb, chlorothalonil, terbutylazine and ethoprophos -contribute to more than 75% of the aquatic ecotoxicity and yet represent less than 40% of the amount used. More than 90% of the human toxicity is generated by only two active substances -namely terbufos and chlorothalonil -whereas they represent less than 10% of the total amount used. Overall, it would be possible to achieve a 90% reduction of human toxicity and a 75% reduction of aquatic ecotoxicity due to pesticide used in Costa Rica, focusing on only a few active substances. For instance, propiconazole or tridemorph could potentially be replaced by chlorothalonil; ametryn, diuron or paraquat by glyphosate; terbufos by cypermethrin; methyl bromide by metam sodium. #

In this paper a discrete-time adaptive sliding mode controller for wheeled mobile robots (WMR) is presented. The dynamical model with time-varying mass has been taken into account. The sliding-mode controller has designed on two components, corresponding to angular and position motion, respectively. In order to accomplish the robustness against parameter uncertainties (robot mass and moment of inertia), an on-line closed loop identification scheme is proposed. In both, angular and position motion controllers, on-line estimation of parameters, which depend on robot mass, is used.

Sterile apple juice inoculated with S. cerevisiae ATCC 9763 (103 CFU/mL) was processed in a bubble column with gaseous ozone of flow rate of 0.12 L/min and concentration of 33–40 μg/mL for 8 min. The growth kinetics of S. cerevisiae as an indicator of juice spoilage was monitored at 4, 8, 12 and 16 °C for up to 30 days. The kinetics was quantitatively described by the primary model of Baranyi and Roberts, and the maximum specific growth rate was further modeled as a function of temperature by the Ratkowsky type model. The developed model was successfully validated for the microbial growth of control and ozonated samples during dynamic storage temperature of periodic changes from 4 to 16 °C. Two more characteristic parameters were also evaluated, the time of spoilage of the product under static temperature conditions and the temperature quotient, Q 10. At lower static storage temperature (4 °C), no spoilage occurred either for unprocessed or ozone-processed apple juice. In the case of ozone-processed apple juice, the shelf life was increased when compared with the controls, and the Q 10 was found to be 7.17, which appear much higher than that of the controls, indicating the effectiveness of ozonation for the extension of shelf life of apple juice.

Accurate single customer models are vital to the development of aggregate dynamic load models which can predict response to direct load control actions. IVitliout such aggregate models, optimal scheduling of direct load control aclions in a manner diich accounts for constraints upon customer c o d o r t is not possible. A dynamic model of the response of a single residential air conditioner load to weather conditions is developed. The model's performance is evaluated using data obtained from the Athens Automation and Control Experiment (AACE), in Athens, Tennessee, and sonie novel approaches to the determination of the parameters of a customer's thermal envelope model are discussed. The model is used to make a prrliiiiinary assessment of the effect of the level of detail upon model accuracy. For the limited number of customers with suitable data aud sur->ey information mho were available in tlie experiment, the variability of paraiiiet,ers aiid responses is assessed.

In this paper, a MATLAB Simulink model for Toyota Prius 2004 hybrid electric vehicle (HEV) is presented. The model is based on MATLAB Simulink HEV model and we covered some of differences between this model and real vehicle and obtain an acceptable model regards to DOE reports.

The reverse engineering of metabolic networks from experimental data is traditionally a labor-intensive task requiring a priori systems knowledge. Using a proven model as a test system, we demonstrate an automated method to simplify this process by modifying an existing or related model--suggesting nonlinear terms and structural modifications--or even constructing a new model that agrees with the system's time series

Plant morphological adjustment in response to spatial resource heterogeneity is an important factor that determines the outcomes of plant-plant and plant-environment interactions. In this study, a dynamic model of resource allocation and growth partitioning at the whole-plant level is presented. The aim is to suggest a mechanism by which plants are capable of modifying their resource allocation to favour the growth of their growing parts sited in resource-rich patches. In this model, an individual plant is treated as a population of relatively independent subunits competing for internal resources. The growth decision of individual shoot and root subunits depends on their local endogenous nutrient status. The allocation of nutrients to different shoot parts and root parts is determined by the structure of the vascular networks. No specific partitioning functions and driving coefficients are introduced in the model to coordinate resource allocation and growth partitioning at the whole-plant level. Vascular tissues acquire resources from the nutrient flow passing through them to grow and maintain their activities. The simulation results show that, based on simple rules of nutrient supply, transport and utilization, plants are able to integrate activities at the whole-plant level to allocate proportionally more growth to their growing parts in the most favourable positions.

The main objective of this paper is to examine in some detail the dynamics and fluctuations in the critical situation for a simple model exhibiting bistable macroscopic behavior. The model under consideration is a dynamic model of a collection of anharmonic oscillators in a two-well potential together with an attractive mean-field interaction. The system is studied in the limit as the number of oscillators goes to infinity. The limit is described by a nonlinear partial differential equation and the existence of a phase transition for this limiting system is established. The main result deals with the fluctuations at the critical point in the limit as the number of oscillators goes to infinity. It is established that these fluctuations are non-Gaussian and occur at a time scale slower than the noncritical fluctuations. The method used is based on the perturbation theory for Markov processes developed by Papanicolaou, Stroock, and Varadhan adapted to the context of probability-measure-valued processes.

The inverse dynamic model of a multibody system is used for many applications in engineering. A very interesting property of these models is that they can be written in a linear form with respect to the inertial parameters of the solids, provided that some conditions hold. This property is very helpful in fields like dynamic parameter identification, design optimization, model reduction and others.

This paper contains a brief overview of the infinitedimensional sampled-data Kalman filter (ISKF) derivation [1]. The ISKF is essentially a mathematical extension of the (finitedimensional) sampled-data Kalman filter that applies to a larger class of problems that satisfy the strongly continuous semigroup property which includes certain partial and delay differential equations.

Genes and proteins form complex dynamical systems or gene regulatory networks (GRN) that can reach several steady states (attractors). These may be associated with distinct cell types. In plants, the ABC combinatorial model establishes the necessary gene combinations for floral organ cell specification. We have developed dynamic gene regulatory network (GRN) models to understand how the combinatorial selection of gene activity is established during floral organ primordia specification as a result of the concerted action of ABC and non-ABC genes. Our analyses have shown that the floral organ specification GRN reaches six attractors with gene configurations observed in primordial cell types during early stages of flower development and four that correspond to regions of the inflorescence meristem. This suggests that it is the overall GRN dynamics rather than precise signals that underlie the ABC model. Furthermore, our analyses suggest that the steady states of the GRN are robust to random alterations of the logical functions that define the gene interactions. Here we Á lvaro Chaos, Max Aldana and Elena Alvarez-Buylla contributed equally to this work.

The paper describes some of the initial results of the CIGRE Working Group C4.605 "Modeling and aggregation of loads in flexible power networks". One of the tasks of the working group is to provide recommendations on developing equivalent static and dynamic models for clusters of diverse loads/generators, i.e., models of distribution network cells and microgrids and recommendations on procedures for data/response gathering and processing. This paper focuses on critical review of existing literature on aggregated models of wind-based generation, active distribution network cells and microgrids for power system studies.

Solar cooling applied to buildings is without a doubt an interesting alternative for reducing energy consumption in traditional mechanical steam compression air conditioning systems. The study of these systems should have a closely purely fundamental approach including the development of numerical models in order to predict the overall installation performance. The final objective is to estimate cooling capacity, power consumption, and overall installation performance with relation to outside factors (solar irradiation, outside temperature.). The first stage in this work consists of estimating the primary energy produced by the solar collector field. The estimation of this primary energy is crucial to ensure the evaluation of the cooling capacity and therefore the cooling distribution and thermal comfort in the building. Indeed, the absorption chiller performance is directly related to its heat source. This study presents dynamic models for double glazing solar collectors and compares the results of the simulation with experimental results taken from our test bench (two collectors). In the second part, we present an extensive collector field model (36 collectors) from our solar cooling installation at The University Institute of Technology in St Pierre, Reunion Island as well as our stratified tank storage model. A comparison of the simulation results with real scale solar experimental data taken from our installation enables validation of the double glazing solar collector and stratified tank dynamic models.

The role of anhydrous magma composition, water content, and crystal content on the dynamics of explosive eruptions is investigated by modeling the ascent of magma along volcanic conduits and the subsequent pyroclastic dispersion in the w atmosphere, described in a companion paper Neri, A., Papale, P., Macedonio, G., 1998. The role of magma composition x and water content in explosive eruptions: 2. Pyroclastic dispersion dynamics. J. Volcanol. Geotherm. Res., 87, 95-115. . The conduit model used is based on the solution of the fundamental transport equations assuming steady-state and isothermal flow conditions, and includes a composition-based description of magma properties and their variations along the conduit. This study stems from the well-documented vertical compositional variation of many pyroclastic deposits, often associated with reconstructed variations in initial water content. The results of the modeling show complex and sometimes non-intuitive dependence of the distribution of the flow variables on magma composition, crystal and water contents. In general, a water content decrease is expected to produce a decrease in mass flow-rate, decrease in pressure and velocity along the conduit, an increase in the exit gas volume fraction, and a decrease in velocity, pressure, and mixture density at the conduit exit. Reverse variations are expected to occur by decreasing the degree of chemical evolution of the liquid at a constant water content, apart from exit velocities which show more complex variations. The overall effect of increasing crystals is in general similar to that of increasing the degree of chemical evolution of the liquid, or decreasing the water content. The above results are to a large extent interpreted in terms of variations in magma viscosity, which is recognized as the critical magma property besides water content in the dynamics of magma ascent. The common compositional trend of explosive eruptions characterized by chemically evolved, water-richer and crystal-poorer magma erupted first is predicted to be associated with variations in the evolution of the eruption dynamics, depending on the relative magnitude of the changes. However, the exit velocity always decreases in the above trend, and the mass flow-rate increases in most relevant cases, comparing well with the results of chemical and stratigraphic studies of the deposits from explosive eruptions. q 1998 Elsevier Science B.V. All rights reserved. 0377-0273r98r$ -see front matter q 1998 Elsevier Science B.V. All rights reserved.

Detailed understanding of landscape changes along the urban-rural gradient provides a useful tool to compare the structural and functional differences of landscape patches at different orientations. Although several case studies have been conducted confirming the efficacy of this approach, integrating temporal data with gradient analysis is still rarely used in practice. In this study, a combination of remote sensing images, landscape metrics and gradient analysis are employed to analyze and compare both the spatial and temporal dynamics of urban sprawl in Guangzhou, China. The results show that landscape change in Guangzhou exhibits distinctive spatial differences from the urban center to rural areas, with higher fragmentation at urban fringes or in new urbanizing areas. Due to the complexity of top-down constraints and local interactions, Guangzhou exhibits a more complex, dynamic, multidimensional configuration of urban sprawl that is different from other cities in China. Urban area expanded towards the north and south areas due to the increased population and rapid economic development. Property market forces and government policy led to the rapid growth towards the southern areas. The study also confirms the hypothesis of diffusion-coalescence urban dynamics model in the process of urbanization. It demonstrates that in order to reveal the complexity of landscape pattern, temporal data are needed to capture the baseline as well as the spatio-temporal dynamics of landscape changes along the gradient. Combining temporal data with gradient analysis can characterize the complex spatial pattern of urbanization in Guangzhou well.

The paper presents a dynamic model considering the human upper limb as a mechanic system with 6 degrees of freedom where the segments are moved by their own weight forces. The bones were modeled in Solid Works, the model of the upper limb obtained being very close as form to the real one. Based on this model, the calculus of

In this paper, proper lumped-parameter models of cam systems are discussed as suitable tools for design purposes. Several models are proposed and described for the estimation of dynamic effects in the behavior of cam transmission systems. A study of successive simplifications is reported by illustrating the corresponding simplified model for a unit cam transmission. The significance and practical application of the simplified models are discussed by deriving a suitable formulation of dynamics equations, whose complexity can be studied through simulation results. RÉSUMÉ: Dans ce travail, des modèles appropriés de paramètre -concentrés des systèmes de came ont été discutés. Plusieurs modèles ont été proposés et décrits pour l'évaluation des effets dynamiques dans le comportement des systèmes de transmission de came. Une étude des simplifications successives est rapportée en illustrant le modèle simplifié correspondant pour des systèmes de transmission de came. La signification et l'application pratique des modèles simplifiés ont été discuté en dérivant une formulation appropriée de l'équation de dynamique, dont la complexité peut être analysée pour moyen de le simulation des résultats.

Human intervention in the hydrologic basin of the Colorado River has eliminated water discharge and sediment supply to the river's mouth and its delta. After ∼95 years of applying strong flow control policies, the previous sedimentary budget in the delta has changed, the delta now being entirely exposed to the hydrodynamic forces in its basin. In order to assess the anthropogenic impact of water diversion on deltaic sedimentary processes and short-term delta geomorphic evolution, textural and mineralogical analyses were performed on 68 sediment samples collected from the river, estuary, beach, continental shelf, delta plain and desert. The results show a consistent NE to SW textural gradient on the shallow-marine platform adjacent to the Colorado River delta (an area known as the Upper Gulf of California), and a net cross-basinal sediment transport occurring in the same direction. Two opposing littoral transport components exist along the Sonoran and Baja Californian coasts: (1) net sediment transport from SE to NW along the Sonoran coast delivers sediments from the ocean into the estuarine basin through the Sonora channel of the deltaic system of the Colorado River; and (2) sediment transport from N to S along the Baja Californian coast removes sediments from the estuarine basin of the Colorado River into the Northern Gulf of California (NGC). The residual sediment transport pattern observed suggests a counterclockwise path of exchange of materials between the estuarine basin of the Colorado River and the NGC. Multivariate cluster and factor analyses of the heavy-mineral data reveal the existence of a sedimentary system dominated by two end-members, representing two heavy-mineral sedimentary provinces: (1) the Sonora province is characterized by a heavy-mineral suite of garnet and zircon (G–Z), whose sediment supply originates from the sandy sediments of the Sonora Mesa deposits and Sonora's Gran Desierto; and (2) the Baja California province is characterized by a hornblende–epidote–pyroxene (H–E–P) suite, whose sediments originate from the earlier supply of the Colorado River. Since the Colorado River is no longer supplying sediments from its drainage basin, the H–E–P-rich sediments now actively dispersed in the system have mainly originated through intense reworking of the delta. Moreover, G–Z-rich sediments are starting to invade areas previously dominated by H–E–P sediments. On the basis of the prevailing hydraulic regime, textural and mineralogical characteristics of the sediments, and hydrographic and bathymetric information from the region, a hypothetical sediment dynamics model for the delta region is proposed, in which the tidally influenced, wave-dominated, sediment-reworked, slightly eroding Sonoran coast changes into a tide-dominated, depositional, very slowly prograding Baja Californian coast. This study shows that human intervention of the hydrologic basin of the Colorado River is not only responsible for inducing drastic hydrologic changes in its estuary (i.e., from brackish to hypersaline), but also for inducing drastic changes in the hydrographic circulation of the receiving basin (i.e., from long-basinal to cross-basinal). These changes are ultimately responsible for the relocation of massive volumes of the delta's sediment inventory, and for the serious ecological impact of habitat loss of indigenous species, such as the now endangered Totoaba (Totoaba macdonaldi) and Vaquita (Phocoena sinus).

This paper analyzes empirically whether and if so to what extent later entrants in the European mobile telephony industry have a disadvantage vis-à-vis incumbents and early mover entrants. To analyze this question a dynamic model of market share development and a series of static models are considered. There is clear evidence of early mover advantage, mainly caused by the influence

Planet formation models suggest the primordial main belt experienced a short but intense period of collisional evolution shortly after the formation of planetary embryos. This period is believed to have lasted until Jupiter reached its full size, when dynamical processes (e.g., sweeping resonances, excitation via planetary embryos) ejected most planetesimals from the main belt zone. The few planetesimals left behind continued to undergo comminution at a reduced rate until the present day. We investigated how this scenario affects the main belt size distribution over Solar System history using a collisional evolution model (CoEM) that accounts for these events. CoEM does not explicitly include results from dynamical models, but instead treats the unknown size of the primordial main belt and the nature/timing of its dynamical depletion using innovative but approximate methods. Model constraints were provided by the observed size frequency distribution of the asteroid belt, the observed population of asteroid families, the cratered surface of differentiated Asteroid (4) Vesta, and the relatively constant crater production rate of the Earth and Moon over the last 3 Gyr. Using CoEM, we solved for both the shape of the initial main belt size distribution after accretion and the asteroid disruption scaling law Q * D . In contrast to previous efforts, we find our derived Q * D function is very similar to results produced by numerical hydrocode simulations of asteroid impacts. Our best fit results suggest the asteroid belt experienced as much comminution over its early history as it has since it reached its low-mass state approximately 3.9-4.5 Ga. These results suggest the main belt's wavy-shaped size-frequency distribution is a "fossil" from this violent early epoch. We find that most diameter D 120 km asteroids are primordial, with their physical properties likely determined during the accretion epoch. Conversely, most smaller asteroids are byproducts of fragmentation events. The observed changes in the asteroid spin rate and lightcurve distributions near D ∼ 100-120 km are likely to be a byproduct of this difference. Estimates based on our results imply the primordial main belt population (in the form of D < 1000 km bodies) was 150-250 times larger than it is today, in agreement with recent dynamical simulations.

A dynamic model of a metal-oxide semiconductor gas sensor is proposed and discussed as a tool for obtaining a substantial reduction of the time needed for sensor calibration. The sensor dynamics turn out to be well represented using a simple exponential model. The prediction of the steady-state value from the initial part of the transient permits a reduction of the