Dynamic Model of WSN

This article reports results from empirical tests of relationships between the pattern of innovation within a firm and certain of the firm's characteristics: the stage of development of its production process and its chosen basis of competition. The hypothesized relationships posed for the present investigation are a synthesis of prior research by the present authors on two distinct but complementary conceptual models of innovation, concerning respectively: the relationship between competitive strategy and innovation, and the relationship between production process characteristics and innovation. The empirical investigation is carried out with data available from the Myers and Marquis study of successful technological innovation in five different industry segments.

An increasing amount of information is being collected on the ecological and socio-economic value of goods and services provided by natural and semi-natural ecosystems. However, much of this information appears scattered throughout a disciplinary academic literature, unpublished government agency reports, and across the World Wide Web. In addition, data on ecosystem goods and services often appears at incompatible scales of analysis and is classified differently by different authors. In order to make comparative ecological economic analysis possible, a standardized framework for the comprehensive assessment of ecosystem functions, goods and services is needed. In response to this challenge, this paper presents a conceptual framework and typology for describing, classifying and valuing ecosystem functions, goods and services in a clear and consistent manner. In the following analysis, a classification is given for the fullest possible range of 23 ecosystem functions that provide a much larger number of goods and services. In the second part of the paper, a checklist and matrix is provided, linking these ecosystem functions to the main ecological, socio-cultural and economic valuation methods. : S 0 9 2 1 -8 0 0 9 ( 0 2 ) 0 0 0 8 9 -7

This article argues that the success of international strategic alliances requires attention not only to the hard side of alliance management (e.g., financial issues and other operational issues) but, also, to the soft side. The soft side refers to the development and management of relationship capital in the alliance. Relationship capital consists of the socio-psychological aspects of the alliance that are positive and beneficial to the alliance. Two important areas of relationship capital are mutual trust and commitment. Based on our findings from two major studies of Japanese strategic alliances, we develop a dynamic model of trust and commitment based on mutual adjustments of alliance partners. We also show how the dynamics of trust and commitment affect the performance of international strategic alliances with the Japanese. The article concludes with a discussion of the managerial implications of our findings and the dynamic model.

In this paper, we present a model of a four rotor vertical take-off and landing (VTOL) unmanned air vehicle known as quadrotor aircraft. And we explained its control architecture including vision based control. Quadrotors have generated considerable interest in both the control community due to their complex dynamics and military because of their advantages over regular air vehicles. The proposed dynamical model which comprises gyroscopic effects and its control strategies can be source for future works.

The notion of Environmental Space refers to external criteria regarding resources available for human consumption. On the one hand, it has been demonstrated that the reduction of energy consumption, material flows and land use would significantly contribute to reducing the main stresses for the European environment. On the other hand, the concept defines a socially motivated minimum of resource availability, permitting to lead a dignified life in the respective society. Environmental space is a tool for exploring sustainable development benchmarks on a sound scientific basis, and it is helpful to derive indicators of sustainable development for different applications on the macro as well as on the micro level. However, the environmental space concept expresses no preference regarding the structure of the economic system, as long as the environmental and social benchmarks are respected, nor does it suggest specific economic sustainability indicators.Since in 1995, the CSD formally introduced the institutional dimension as the fourth dimension of sustainable development, sustainable development can be described by referring to four dimensions and their six interlinkages.Using the Prism of Sustainability, the concept—although rather complex—can easily be communicated and used as a tool for gathering public support for sustainability policies. The prism simplifies matters by structuring them, but avoids the oversimplification inherent to aggregate indices.At the macro level, the environmental space and the prism of sustainability have been applied to international, regional and national indicator development. At the micro level, systems of indicators for households, companies and local communities have been developed.The indicators have also been used in dynamic modeling, demonstrating their capability to assess the sustainability of different policy strategies.

In this paper we develop a dynamic model for integer counts to capture fundamental properties of financial prices at the transaction level. Our model relies on an autoregressive multinomial component for the direction of the price change and a dynamic count data component for the size of the price changes. Since the model is capable of capturing a wide range of discrete price movements it is particularly suited for financial markets where the trading intensity is moderate or low. We present the model at work by applying it to transaction data of two shares traded at the NYSE traded over a period of one trading month. We show that the model is well suited to test some theoretical implications of the market microstructure theory on the relationship between price movements and other marks of the trading process. Based on density forecast methods modified for the case of discrete random variables we show that our model is capable to explain large parts of the observed distribution of pr...

this paper presents the modelling of a four rotor vertical take-off and landing (VTOL) unmanned air vehicle known as the quadrotor aircraft. The paper presents a new model design method for the flight control of an autonomous quad rotor .The paper describes the controller architecture for the quadrotor as well. The dynamic model of the quad-rotor, which is an under actuated aircraft with fixed four pitch angle rotors, will be described. The Modeling of a quadrotor vehicle is not an easy task because of its complex structure. The aim is to develop a model of the vehicle as realistic as possible. The model is used to design a stable and accurate controller. This paper explains the developments of a PID (proportionalintegral-derivative) control method to obtain stability in flying the Quad-rotor flying object. The model has four input forces which are basically the thrust provided by each propeller connected to each rotor with fixed angle. Forward (backward) motion is maintained by increasing (decreasing) speed of front (rear) rotor speed while decreasing (increasing) rear (front) rotor speed simultaneously which means changing the pitch angle. Left and right motion is accomplished by changing roll angle by the same way. The front and rear motors rotate counter-clockwise while other motors rotate clockwise so that the yaw command is derived by increasing (decreasing) counter-clockwise motors speed while decreasing (increasing) clockwise motor speeds.

Supply chains are complicated dynamical systems triggered by customer demands. Proper selection of equipment, machinery, buildings and transportation fleets is a key component for the success of such systems. However, efficiency of supply chains mostly depends on management decisions, which are often based on intuition and experience. Due to the increasing complexity of supply chain systems (which is the result of changes in customer preferences, the globalization of the economy and the stringy competition among companies), these decisions are often far from optimum. Another factor that causes difficulties in decision making is that different stages in supply chains are often supervised by different groups of people with different managing philosophies. From the early 1950s it became evident that a rigorous framework for analyzing the dynamics of supply chains and taking proper decisions could improve substantially the performance of the systems. Due to the resemblance of supply chains to engineering dynamical systems, control theory has provided a solid background for building such a framework. During the last half century many mathematical tools emerging from the control literature have been applied to the supply chain management problem. These tools vary from classical transfer function analysis to highly sophisticated control methodologies, such as model predictive control (MPC) and neuro-dynamic programming. The aim of this paper is to provide a review of this effort. The reader will find representative references of many alternative control philosophies and identify the advantages, weaknesses and complexities of each one. The bottom line of this review is that a joint co-operation between control experts and supply chain managers has the potential to introduce more realism to the dynamical models and develop improved supply chain management policies. ᭧

This article discusses inter-partner relationships and their impact on joint venture performance. It explores the changes in the nature of relationships (conflict, commitment, co-operation, trust) which have important implications for the continuity and performance of partnerships. In doing so, it identifies the potential areas of co-operation and conflict, due to both partners' overlapping interests, and establishes constructs which help explain conflict, commitment and other soft dimensions of joint venture operations. Based on previous studies, this article develops a framework within which inter-partner relations (conflict, commitment, trust, cooperation, and autonomy) are empirically examined. The article also establishes performance constructs for joint venture organisations. Finally, it develops a dynamic model of inter-partner relations and performance which indicates the causal connections between conflict, commitment, control, inter-partner co-operation and performance.

ABSTRACT We analyze friendship formation patterns and develop a dynamic model of friendship formation that combines choices with random meeting patterns. We estimate biases in agents' preferences over the races of their friends and biases in the rates at which agents of various races meet each other. We find that both biases are significant in the data and that the biases differ significantly across races.

In this paper, the dynamic model of a wheeled inverted pendulum (e.g., Segway, Quasimoro, and Joe) is analyzed from a controllability and feedback linearizability point of view. First, a dynamic model of this underactuated system is derived with respect to the wheel motor torques as inputs while taking the nonholonomic no-slip constraints into considerations. This model is compared with the previous models derived for similar systems. The strong accessibility condition is checked and the maximum relative degree of the system is found. Based on this result, a partial feedback linearization of the system is obtained and the internal dynamics equations are isolated. The resulting equations are then used to design two novel controllers. The first one is a two-level velocity controller for tracking vehicle orientation and heading speed set-points, while controlling the vehicle pitch (pendulum angle from the vertical) within a specified range. The second controller is also a two-level controller which stabilizes the vehicle's position to the desired point, while again keeping the pitch bounded between specified limits. Simulation results are provided to show the efficacy of the controllers using realistic data.

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.

In this paper, we develop a structural model of household behavior in an environment where there is uncertainty about brand attributes, and both prices and advertising signal brand quality. Four quality signaling mechanisms are at work in the model: 1) price signals quality, 2) advertising frequency signals quality, 3) advertising content provides direct (but noisy) information about quality, and 4) use experience provides direct (but noisy) information about quality. We estimate our proposed model using scanner panel data on ketchup. If price is important as a signal of brand quality, then frequent price promotion may have the unintended consequence of reducing brand equity. We use our estimated model to measure the importance of such effects. Our results imply that price is an important quality signaling mechanism, and that frequent price cuts can have significant adverse effects on brand equity. The role of advertising frequency in signaling quality is also significant, but it is less quantitatively important than price.

A method of evaluating the intermittent propeller blade fixed cavitation and shedding of free cavitation bubbles is presented. The number and size of free cavitation bubbles are related to the variation of propeller blade attached cavitation. The beta type probability density distribution of the initial bubble size is proposed. This distribution is normalized with respect to the sheet cavitation thickness. The effect of the simplications in the dynamic model of the cavitation bubbles on their collapse downstream of partially and fully cavitating hydrofoils is discussed. The method of calculating the low frequency pressures induced by fixed blade cavitation and high frequency broadband noise caused by the collapse of free bubbles in propeller flows is presented. The method yields noise spectra in the frequency range from the blade passing frequency to tens of kiloHertz. Computed pressure and noise induced by the cavitating propellers are compared to the values measured in model and full scale experiments. The fractal structure of the bubble cloud and the proposed method of evaluating the collapse of the bubble cloud downstream of the fixed cavities yield noise spectra which correlate well with the experimental results of full and model scale measurements.

Recent research and development of alternative energy sources have shown excellent potential as a form of contribution to conventional power generation systems. In order to meet sustained load demands during varying natural conditions, different energy sources and converters need to be integrated with each other for extended usage of alternative energy. The paper focuses on the combination of wind, fuel cell (FC) and ultra-capacitor (UC) systems for sustained power generation. As the wind turbine output power varies with the wind speed: an FC system with a UC bank can be integrated with the wind turbine to ensure that the system performs under all conditions. We propose herein a dynamic model, design and simulation of a wind/FC/UC hybrid power generation system with power flow controllers. In the proposed system, when the wind speed is sufficient, the wind turbine can meet the load demand while feeding the electrolyzer. If the available power from the wind turbine cannot satisfy the load demand, the FC system can meet the excess power demand, while the UC can meet the load demand above the maximum power available from the FC system for short durations. Furthermore, this system can tolerate the rapid changes in wind speed and suppress the effects of these fluctuations on the equipment side voltage in a novel topology. (M.S. Alam). trical energy via fuel cells (FCs). This type of energy storage provides significant advantages when compared to conventional batteries in terms of energy density and long-term storage [2,3]. By using an electrolyzer, hydrogen conversion allows both storage and transportation of large amounts of power at much higher energy densities . Thus, hydrogen generation can lead a pathway for wind-based energy generation to contribute directly to reducing the dependence on imported fossil fuel . According to Ref. [6,, wind electrolysis is an attractive candidate for economically viable renewable-hydrogen production system. Furthermore, coupling wind turbines with electrolyzers has the potential to provide low-cost, environmentally friendly distributed generation of hydrogen in addition to electricity . Thus, the stored hydrogen energy can be used by FC power plants during the low wind speed conditions. FC power plants use oxygen and hydrogen to convert chemical energy into electrical energy. Among the various types of FC systems, proton exchange membrane (PEM) FC power plants have been found to be especially suitable for hybrid energy systems with higher power density and lower operating temperature. However, assisting an FC power plant with a parallel 0378-7753/$ -see front matter alternative energy sources, fuel cells, energy conversion, power system modeling, analysis and control, power quality, active harmonic and EMI filtering in nonlinear systems and power system stability.

With the advent of high-speed trains, there is a renewed interest in the rail track-vehicle interaction studies. As part of an ongoing investigation of the track system optimisation and fatigue of the track components, a dynamic model is developed to examine the vertical interaction of the rail track and the wagon system. Wagon with four wheelsets representing two bogies is modelled as a 10 degree of freedom subsystem, the track is modelled as a four-layer subsystem and the two subsystems are coupled together via the non-linear Hertz contact mechanism. The current model is validated using several field test data and other numerical models reported in the literature by other researchers. Ó

We present our ongoing work on the development of a new quadrotor aerial vehicle which has a tilt-wing mechanism. The vehicle is capable of take-off/landing in vertical flight mode (VTOL) and flying over long distances in horizontal flight mode. Full dynamic model of the vehicle is derived using Newton-Euler formulation. Linear and nonlinear controllers for the stabilization of attitude of

This paper aims to show that aggregate tax evasion may be largely explained by tax morale and that tax morale is dependent on the taxpayers' intrinsic attitudes to honesty and social stigma. The theoretical hypothesis is that these attitudes are influenced by the taxpayers' perceptions of the size of tax evasion as well as by their perceptions of the policy maker's effectiveness in exercising control over the relevant macroeconomic variables and safeguarding the interests of citizens. Applying Gordon's [Gordon, J.P.F., 1989. Individual morality and reputation costs as deterrents to tax evasion. European Economic Review 33(4), 797-805] framework, a dynamic model of aggregate tax evasion is proposed whereby multiple equilibria may emerge. Econometric analysis on Latin American countries supports the assumptions made in the model.

The purpose of this article is to present an integrative model of cross-cultural counseling and psychotherapy. Illustrated by a series of critical incidents, it is argued that unidimensional models of cross-cultural counseling and psychotherapy are inherently limited. Using Kluckhohn and Murray's tripartite model of personality, an integrative, sequential, and dynamic model of cross-cultural counseling is advanced. Support for the validity of the Kluckhohn and Murray model is first reviewed. This is followed by a delineation of the components of the current integrative model: (a) Outgroup homogeneity effect, (b) Cultural schema theory, (c) Complimentarity theory, (d) Science of complexity, and (e) Mindfulness. The operation of this model is described in a series of figures and the implications for counseling practice and future research is discussed.

This paper focuses on the problem of wind turbine fatigue load reduction by means of individual pitch control (IPC). The control approach has a two-degree-of-freedom structure, consisting of an optimal multivariable LQG controller and a feedforward disturbance rejection controller based on estimated wind speed signals. To make the control design problem time invariant, all signals are transformed to the non-rotating reference frame using the Coleman transformation. In the Coleman domain, the LQG control objective is minimization of the rotor tilt and yaw moments, whereas the feedforward controller tries to achieve even further improvement by rejecting the influence of the low-frequency components of the wind on the rotor moments. To this end, the tilt-and yaw-oriented components of the blade-effective wind speeds are approximated using stochastic random walk models, the states of which are then augmented with the turbine states and estimated using a Kalman filter. The effects of these (estimated) disturbances on the controlled outputs are then reduced using stable dynamic model inversion. The approach is tested and compared with the conventional IPC method in simulation studies with models of different complexities. The results demonstrate very good load reduction at not only low frequencies (1p blade fatigue load reduction) but also at the 3p frequency, giving rise to fatigue load reduction of the non-rotating turbine components.

Autonomous vehicle navigation with standard IMU and differential GPS has been widely used for aviation and military applications. Our research interesting is focused on using some low-cost off-the-shelf sensors, such as strap-down IMU, inexpensive single GPS receiver. In this paper, we present an autonomous vehicle navigation method by integrating the measurements of IMU, GPS, and digital compass. Two steps are adopted to overcome the low precision of the sensors. The first is to establish sophisticated dynamics models which consider Earth self rotation, measurement bias, and system noise. The second is to use a sigma Kalman filter for the system state estimation, which has higher accuracy compared with the extended Kalman filter. The method was evaluated by experimenting on a land vehicle equipped with IMU, GPS, and digital compass.

A new optimal control law for direct yaw moment control, to improve the vehicle handling, is developed. Although, this can be considered as part of a multi-layer system, for the traction control of a motorized wheels electric vehicle, but the results of this study are quite general and can be applied to other types of vehicles. The dynamic model of the vehicle system is initially developed and, using the well-known optimal control theory, an optimal controller is designed. Two different versions of control laws are considered here and the performance of each version of the control law is compared with the other one. The numerical simulation of the vehicle handling with and without the use of the optimal yaw moment controller, and assuming a comprehensive non-linear vehicle dynamic model, has been carried out. Simulation results obtained indicate that considerable improvements in the vehicle handling can be achieved whenever the vehicle is governed by the optimal yaw moment control.

In this paper self-tuning fuzzy PID controller is developed to improved the performance for a pitch control of aircraft system. The controller is designed based on the dynamic modeling of system begins with a derivation of suitable mathematical model to describe the longitudinal motion of an aircraft. Fuzzy logic is used to tune each parameter of Proportional-integral-derivative (PID) controller by selecting appropriate fuzzy rules through simulation in Matlab and Simulink. Comparative assessment based on time response specifications between conventional PID controller with self-tuning fuzzy PID for an autopilot of longitudinal dynamic in pitch aircraft is investigated and analyzed. Simulation results show that, the performance of a pitch control system has improved significantly using self-tuning fuzzy PID compared to conventional PID controller.

Lean manufacturing is an integrated socio-technical system. Its main objectives are to eliminate waste and reduce the variability of suppliers, customers, and internal resources and processes. A "lean" roadmap guides the transition from an existing operation to one that fully implements a "lean" philosophy and its best practices. In this study a comparative literature review showed that there is no standard model in use for implementing "lean". Existing research indicates that there are 3 phases that incorporate 22 steps to "leanness" and the following "lean" steps are frequently cited: pilot project, planning, objectives, training, and value stream mapping. Based on the findings, a dynamic model for a "lean" roadmap was proposed to account for the dynamic conditions of a high variability environment.

This paper argues that researchers in the area of educational effectiveness should attempt to develop a new theoretical framework. Thus, a critical analysis of the current models of educational effectiveness research is provided and reveals that a dynamic model of effectiveness must: a) be multilevel in nature, b) be based on the assumption that the relation of some effectiveness factors with achievement may be curvilinear, c) illustrate the dimensions upon which the measurement of each

Time-optimal control of startup traditional distillation columns by iterative programming proposed by Woinaroschy for ideal [Ind. Eng. Chem. Res. 2008, 47, 4158] and nonideal mixtures [Ind. Eng. Chem. Res. 2009, 48, 3873] is extended to the case of dividing-wall distillation columns. The minimization of distillation startup time is performed by iterative dynamic programming employing randomly chosen candidates for admissible control. The control variables are the reflux ratio, the reboiler heat duty, and the side-draw flow rate. The dynamic distillation model proposed by the author in the previous papers is applied. Two illustrative case studies for the separation in a dividing-wall column with sieve trays and lateral downcomers are presented as follows: the separation of an ideal benzene-toluene-ethylbenzene ternary mixture and the separation of a nonideal methanol-ethanol-1-propanol mixture. In another case study, a conventional two-column system is presented in comparison to the dividing-wall column. As in the cases of traditional distillation columns, the startup time decrease and the corresponding reboiler energy savings are significant for each of the control variables.

Anaerobic digestion enables waste (water) treatment and energy production in the form of biogas. The successful implementation of this process has lead to an increasing interest worldwide. However, anaerobic digestion is a complex biological process, where hundreds of microbial populations are involved, and whose start-up and operation are delicate issues. In order to better understand the process dynamics and to optimize the operating conditions, the availability of dynamic models is of paramount importance. Such models have to be inferred from prior knowledge and experimental data collected from real plants.

Supervisory control Ultra-capacitor a b s t r a c t Depending on growing concerns on energy crises and environmental issues, fuel cell (FC) powered electrical vehicles are favored for possible substitute to conventional internal combustion engine (ICE) based vehicular systems. However, the typical power profile of an automobile motor consisting of transients is not suitable for the use of a sole FC system for vehicle propulsion. This shortcoming could be partly overcome by hybridization. Two potential benefits of combining an FC system with an energy storage unit, ultra-capacitor (UC) has been presented in this study. Firstly, the durability of the FC system could be improved because the additional energy source can fulfill the transient power demand fluctuations. Secondly, the ability of the energy storage source to recover braking energy enhances the fuel economy greatly. An important aspect in designing a hybrid power structure is to find a suitable control strategy that can manage the active power sharing and take advantage of the inherent scalability and robustness benefits of the hybrid system. An integrated procedure for mathematical modeling and power control strategy design for an FC/UC hybrid vehicle is presented in this paper. A fuzzy logic supervisory controller based power management strategy that secures the power balance in hybrid structure, enhances the FC performance and minimizes the power losses is proposed. The main contribution of this paper apart from the previous studies of the authors is the modeling of the complete FC power system with air supply compressor and the integration of the control of the FC system internal dynamics (especially the oxygen excess ratio) into the overall supervisory control structure to maximize the efficiency and durability. To demonstrate the effectiveness of the proposed power management scheme, simulation studies were performed using MATLAB Ò , Simulink Ò and SimPowerSystems Ò environments by integrating the detailed mathematical and electrical models of the hybrid vehicular system.

In this work a dynamic model of a new quadrotor aerial vehicle that is equipped with a tilt-wing mechanism is presented. The vehicle has the capabilities of vertical take-off/landing (VTOL) like a helicopter and flying horizontal like an airplane. Dynamic model of the vehicle is derived both for vertical and horizontal flight modes using Newton-Euler formulation. An LQR controller for the vertical flight mode has also been developed and its performance has been tested with several simulations. Keywords—Control, Dynamic model, LQR, Quadrotor, Tilt-wing, VTOL.

Over the last two decades, significant research effort has been directed towards developing vehicle transmissions that reduce the energy consumption of an automobile. This effort has been a direct consequence of the growing environmental concern imposing the directives of reduced exhaust emissions and increased vehicle efficiency on current vehicle manufacturers and users. A continuously variable transmission (CVT) offers a continuum of gear ratios between desired limits, which consequently enhances the fuel economy and dynamic performance of a vehicle by better matching the engine operating conditions to the variable driving scenarios. Although a CVT plays a crucial role in the plan to improve vehicle fuel economy, its complete potential has not been realized in a mass-production vehicle. The current paper reviews the state-of-the-art research on dynamic modeling and control of friction-limited continuously variable transmissions. The basic concepts, mathematical models, and computational schemes are extensively discussed. Challenges and critical issues for future research on modeling and control of such CVTs are also discussed.

This paper provides comprehensive development procedures and final forms of mathematical models of unified power flow controller (UPFC) for steadystate, transient stability a$ eigenvalue studies. Based on the developed models, the impacts of control strategy, parameters and location of UPFC on power system operating conditions are discussed. The accuracy of the developed models is verified through comparing the study results with those obtained from detailed time-domain simulation using the Electromagnetic Transients Program (EMTP).

The current legislation imposes tighter restrictions in order to reduce the impact of chemical process industry on the environment. In this context, this study presents the dynamic model, simulation and optimization results for an industrial sulfuric acid plant. The dynamic model, implemented in PSE gPROMS includes a catalytic reactor (five pass converter), heat exchangers such as economizers and feed-effluent heat exchangers, mixers, splitters and reactive absorption columns. The kinetic parameters were fitted to the real plant data, while the remaining model parameters were estimated using classical correlations. The modeling results agree very well with the real plant data.

C and N mineralisation kinetics obtained in laboratory incubations during decomposition of crop residues under non-limiting nitrogen conditions were simulated using a simple dynamic model. This model includes three compartments: the residues, microbial biomass and ...

Married women's labor force participation has increased dramatically over the last century. Why this has occurred has been the subject of much debate. This paper investigates the role of culture as learning in this change. To do so, it develops a dynamic model of culture in which individuals hold heterogeneous beliefs regarding the relative long-run payoffs for women who work in the market versus the home. These beliefs evolve rationally via an intergenerational learning process. Women are assumed to learn about the long-term payoffs of working by observing (noisy) private and public signals. They then make a work decision. This process generically generates an S-shaped figure for female labor force participation, which is what is found in the data. The S shape results from the dynamics of learning. I calibrate the model to several key statistics and show that it does a good job in replicating the quantitative evolution of female LFP in the US over the last 120 years. The model highlights a new dynamic role for changes in wages via their effect on intergenerational learning. The calibration shows that this role was quantitatively important in several decades.