Directory of Open Access Journals (Sweden)
Mohammad Ghahremanzadeh
2014-06-01
Full Text Available Agriculture as one of the major economic sectors of Iran, has an important role in Gross Domestic Production by providing about 14% of GDP. This study attempts to forecast the value of the agriculture GDP using Periodic Autoregressive model (PAR, as the new seasonal time series techniques. To address this aim, the quarterly data were collected from March 1988 to July 1989. The collected data was firstly analyzed using periodic unit root test Franses & Paap (2004. The analysis found non-periodic unit root in the seasonal data. Second, periodic seasonal behavior (Boswijk & Franses, 1996 was examined. The results showed that periodic autoregressive model fits agriculture GDP well. This makes an accurate forecast of agriculture GDP possible. Using the estimated model, the future value of quarter agricultural GDP from March 2011 to July 2012was forecasted. With consideration to the fair fit of this model with agricultural GDP, It is recommended to use periodic autoregressive model for the future studies.
SINGLE-PERIOD TWO-PRODUCT INVENTORY MODEL WITH SUBSTITUTION:SOLUTION AND PROPERTIES
Institute of Scientific and Technical Information of China (English)
Lianqiao CAI; Jian CHEN; Houmin YAN
2004-01-01
In this paper, we study a single-period two-product inventory model with stochastic demands and downward substitution. The optimal order quantities are presented and some properties are provided. Comparing with newsboy model, we prove that both the profit and the fill rate can be improved by using the substitution policy.
Forecasting Labour Productivity Growth in Norway for the Period 2012-2021 Using ARIMA Models
Directory of Open Access Journals (Sweden)
Pirooz Samavati
2013-06-01
Full Text Available There appeared to be a change in labour productivity growth in Norway (a fall in the growth rate in the middle of the 2000s, followed by a slight recovery at the end of the period under consideration (1971-2011. The 2007-2009 financial and economic crisis in Norway (which resulted from the banking crisis caused an even greater drop in labour productivity growth to the extent that it in 2008 it reached its lowest point over the last three decades. After 2008, labour productivity growth started to increase. In this paper, in order to forecast time-series labour productivity growth in Norway for the period 2012-2021, the ARIMA model is fitted to Norwegian time-series labour productivity growth data obtained in the period 1971-2011. Using the Box-Jenkins model selection methodology, ARIMA (1, 1, 1 with no constant is selected as an appropriate model. As the selected ARIMA model indicates, labour productivity growth in Norway shall continue to increase very slowly and will ultimately reach a non-zero constant in the forecast period (2012-2021 following its recovery after 2008. Long-term forecasts for time-series labour productivity growth in Norway using ARIMA (1, 1, 1 with no constant will also reach a non-zero constant. Initially, it might be concluded that slow technological development as a result of the 2007-2009 financial and economic crisis could explain the slowdown in the recovery of labour productivity growth both in the forecast period (2012-2021 and over the longer term. However, due to the fact that the 2007-2009 financial and economic crisis has changed the underlying process which Norwegian labour productivity growth rate followed in the immediately preceding period, and that a technological revolution, which can be considered as a contributing factor, also took place in that period, it seems unlikely that a single labour productivity growth time series will be rich enough to describe the variation in the data. From the data and the
Directory of Open Access Journals (Sweden)
mostafa gholamrezaii rahimi
2015-09-01
Full Text Available Production planning is one of the most important tasks of production and operations management and decides to determine the optimum amount of production, labor and inventory levels for each period of planning horizon with regard to productive resources and limits. This research presents a multi-product and multi-objective model of production planning with fuzzy parameters and soft constraints regarding the time value of money, inventory level, labor, capacity of machines and warehouse space. The proposed model attempts to maximize profit of the sale and minimize carrying and backordering costs and changes in labor levels. Case study conducted in the aluminum factory, shows the performance of this model comparing the current situation.
Directory of Open Access Journals (Sweden)
Kaveh Khalili-Damghani
2017-07-01
Full Text Available In this paper a multi-period multi-product multi-objective aggregate production planning (APP model is proposed for an uncertain multi-echelon supply chain considering financial risk, customer satisfaction, and human resource training. Three conflictive objective functions and several sets of real constraints are considered concurrently in the proposed APP model. Some parameters of the proposed model are assumed to be uncertain and handled through a two-stage stochastic programming (TSSP approach. The proposed TSSP is solved using three multi-objective solution procedures, i.e., the goal attainment technique, the modified ε-constraint method, and STEM method. The whole procedure is applied in an automotive resin and oil supply chain as a real case study wherein the efficacy and applicability of the proposed approaches are illustrated in comparison with existing experimental production planning method.
Institute of Scientific and Technical Information of China (English)
熊中楷; SHEN; Tiesong
2002-01-01
This paper presents an optimal production model for manufacturer in a supply chain with a fixed demand at a fixed interval with respect to the learning effect on production capacity.An algorithm is employed to find theoptimal dela time for production and production time sequentially.It is found that the optimal delay time for production and the production time are not static,but dynamic and variant with time.It is important for a manufacturer to schedule the production so as to prevent facilities and workers from idling.
A MULTI-PRODUCT AND MULTI-PERIOD FACILITY LOCATION MODEL FOR REVERSE LOGISTICS
Benaissa Mounir; Benabdelhafid Abdellatif
2010-01-01
Reverse logistics has become an important entity in the world economy. Businesses increasingly have to cope with product returns, mandated environmental regulations and increasing costs associated with product disposal. This study presents a cost-minimization model for a multi-time-step, multi-type product waste reverse logistics system. The facility location is a central issue of the logistics networks. In this article we are interested in optimizing of the sites facility location for a reve...
A Cost Model of Partial Postponement Strategy of the Single-Period Product under Stochastic Demand
Directory of Open Access Journals (Sweden)
Yanhong Qin
2012-06-01
Full Text Available The target of our study is to set a new cost model to solve the partial postponement problem by adding penalty cost parameter of shortage under stochastic demand. By doing this, we hope the new model can be better applied to real conditions. Postponement is an important strategy to achieve mass customization and it has been adopted by many companies to improve production operation, inventory and logistics management and supply chain operation, but the postponed activity will cause additional costs at the same time. There have been many literatures trading off between the relative cost and the postponement benefits of product manufacture, and our paper is to solve the similar problem.
Ph.H.B.F. Franses (Philip Hans); R. Paap (Richard)
2004-01-01
textabstractThis book considers periodic time series models for seasonal data, characterized by parameters that differ across the seasons, and focuses on their usefulness for out-of-sample forecasting. Providing an up-to-date survey of the recent developments in periodic time series, the book
Frank W. Ciarallo; Ramakrishna Akella; Thomas E. Morton
1994-01-01
Increasing product complexity, manufacturing environment complexity and an increased emphasis on product quality are all factors leading to uncertainties in production processes. These uncertainties are in the form of unplanned machine maintenance, varying production yields and rework, among others. In planning for production, an adequate model must incorporate these uncertainties into the representation of the production process. This paper treats the aggregate planning problem for a single ...
Sourice, Sophie; Nisole, Audrey; Guéguen, Jacques; Popineau, Yves; Elmorjani, Khalil
2003-12-26
Primary structures of wheat prolamins contain repetitive domains involved in the mechanical properties of gluten. In order to experience the ability of recombinant strictly periodic polypeptides, modelled on a consensus sequence of wheat gliadins (PQQPY)(8) and (PQQPY)(17) (SPR8 and SPR17 polypeptides, respectively), to be formulated in film solutions, their heterologous expression conditions, in batch culture and low cell densities, were optimized to match the high requirements of this process. A convenient and general purification procedure was also devised. Moreover, FTIR-ATR characterizations indicated that these periodic polypeptides prepared as hydrated doughy state and dried have the tendency to form a protein network through intermolecular beta-sheets, strongly maintained by hydrogen bonds. Accordingly, these recombinant polypeptides are assumed to be a suitable candidate for potential application.
Sensitivity analysis of periodic matrix population models.
Caswell, Hal; Shyu, Esther
2012-12-01
Periodic matrix models are frequently used to describe cyclic temporal variation (seasonal or interannual) and to account for the operation of multiple processes (e.g., demography and dispersal) within a single projection interval. In either case, the models take the form of periodic matrix products. The perturbation analysis of periodic models must trace the effects of parameter changes, at each phase of the cycle, on output variables that are calculated over the entire cycle. Here, we apply matrix calculus to obtain the sensitivity and elasticity of scalar-, vector-, or matrix-valued output variables. We apply the method to linear models for periodic environments (including seasonal harvest models), to vec-permutation models in which individuals are classified by multiple criteria, and to nonlinear models including both immediate and delayed density dependence. The results can be used to evaluate management strategies and to study selection gradients in periodic environments.
Sobacchi, Emanuele; Stamerra, Antonio
2016-01-01
We describe a scenario to explain blazar periodicities with timescales of $\\sim$ few years. The scenario is based on a binary super-massive black hole (SMBH) system in which one of the two SMBH carries a jet. We discuss the various mechanisms that can cause the jet to precess and produce corkscrew patterns through space with a scale of $\\sim$ few pc. It turns out that the dominant mechanism responsible for the precession is simply the imprint of the jet-carrying SMBH orbital speed on the jet. Gravitational deflection and Lense-Thirring precession (due to the gravitational field of the other SMBH) are second order effects. We complement the scenario with a kinematical jet model which is inspired to the spine-sheath structure observed in M87. One of the main advantages of such a structure is that it allows the peak of the synchrotron emission to scale with frequency according to $\
DEFF Research Database (Denmark)
Sazvar, Z.; Mirzapour Al-e-hashem, S. M J; Govindan, K.
2016-01-01
One of the main challenges of retail units is to determine the order quantities of different types of products, each with a specific expiry date, so that the system cost including shortage cost is minimized. We study a new multi-product multi-period replenishment problem for a First Expired...
Optimizing metabolite production using periodic oscillations.
Directory of Open Access Journals (Sweden)
Steven W Sowa
2014-06-01
Full Text Available Methods for improving microbial strains for metabolite production remain the subject of constant research. Traditionally, metabolic tuning has been mostly limited to knockouts or overexpression of pathway genes and regulators. In this paper, we establish a new method to control metabolism by inducing optimally tuned time-oscillations in the levels of selected clusters of enzymes, as an alternative strategy to increase the production of a desired metabolite. Using an established kinetic model of the central carbon metabolism of Escherichia coli, we formulate this concept as a dynamic optimization problem over an extended, but finite time horizon. Total production of a metabolite of interest (in this case, phosphoenolpyruvate, PEP is established as the objective function and time-varying concentrations of the cellular enzymes are used as decision variables. We observe that by varying, in an optimal fashion, levels of key enzymes in time, PEP production increases significantly compared to the unoptimized system. We demonstrate that oscillations can improve metabolic output in experimentally feasible synthetic circuits.
DEFF Research Database (Denmark)
Svensson, Carsten
2002-01-01
The Project is co-financed with Nilpeter A/S and investigates the industrialization of build to order production. Project content: - Enterprise engineering - Specification processes - Mass Customization/ Build To Order - Knowledge/information management - Configuration - Supply Chain Management...
DEFF Research Database (Denmark)
Svensson, Carsten
2002-01-01
The Project is co-financed with Nilpeter A/S and investigates the industrialization of build to order production. Project content: - Enterprise engineering - Specification processes - Mass Customization/ Build To Order - Knowledge/information management - Configuration - Supply Chain Management...
可替代产品库存模型的研究%Single-Period Two-Product Inventory Model with Reorder and Substitution
Institute of Scientific and Technical Information of China (English)
李小申; 夏尊铨
2008-01-01
In market, many same or similar-characteristic products can substitute for each other, retailers usually adopt substitution strategy for more benefits, and excess demand for product can also be met by reorder. For single-period two-product inventory problem of this kind, we develop the profits maximization model with stochastic demands and proportional costs and revenues. We show that the objective function is concave and submodular, and therefore the optimal stock policy exists. We present the optimal conditions for stock quantities, and provide some properties of the optimal stock quantities. We explore the impacts of parameters on the profits and the optimal stock quantities. By comparison we prove that reorder, and adoption of the substitution strategy for special cases, can raise the profits and reduce the general stock level.%市场上,很多产品之间可相互替代,商家为了获得的更多的利润,经常会用一种产品替代另一种产品.不仅如此.某种产品缺货时,也可以重新进货以满足顾客的需求.我们从销售商的角度,讨论这两个因素对库存策略的影响,建立了这类问题有两个产品的单周期的利润最大化模型,证明了目标函数是凹的和子模的,从而问题的解是存在的,给出了最优订货量(原始库存)的必要条件,讨论了各参数对库存的影响.通过比较,证明了商家采取替代策略和允许再订货可以提高利润并且可减少库存总量.
From Product Models to Product State Models
DEFF Research Database (Denmark)
Larsen, Michael Holm
1999-01-01
A well-known technology designed to handle product data is Product Models. Product Models are in their current form not able to handle all types of product state information. Hence, the concept of a Product State Model (PSM) is proposed. The PSM and in particular how to model a PSM is the Research...... Object for this project. In the presentation, benefits and challenges of the PSM will be presented as a basis for the discussion....
Directory of Open Access Journals (Sweden)
E. E. Popova
2006-07-01
Full Text Available The use of 6 h, daily, weekly and monthly atmospheric forcing resulted in dramatically different predictions of plankton productivity in a global 3-D coupled physical-biogeochemical model.
Resolving the diurnal cycle of atmospheric variability by use of 6 h forcing, and hence also diurnal variability in UML depth, produced the largest difference, reducing predicted global primary and new production by 25% and 10% respectively relative to that predicted with daily and weekly forcing. This decrease varied regionally, being a 30% reduction in equatorial areas and 25% at moderate and high latitudes. A 10% increase in the primary production was seen in the peripheries of the oligotrophic gyres.
By resolving the diurnal cycle, model performance was significantly improved with respect to several common problems: underestimated primary production in the oligotrophic gyres; overestimated primary production in the Southern Ocean; overestimated magnitude of the spring bloom in the subarctic Pacific Ocean, and overestimated primary production in equatorial areas. The result of using 6 h forcing on predicted ecosystem dynamics was profound, the effects persisting far beyond the hourly timescale, and having major consequences for predicted global and new production on an annual basis.
Forecasting with periodic autoregressive time series models
Ph.H.B.F. Franses (Philip Hans); R. Paap (Richard)
1999-01-01
textabstractThis paper is concerned with forecasting univariate seasonal time series data using periodic autoregressive models. We show how one should account for unit roots and deterministic terms when generating out-of-sample forecasts. We illustrate the models for various quarterly UK consumption
Forecasting with periodic autoregressive time series models
Ph.H.B.F. Franses (Philip Hans); R. Paap (Richard)
1999-01-01
textabstractThis paper is concerned with forecasting univariate seasonal time series data using periodic autoregressive models. We show how one should account for unit roots and deterministic terms when generating out-of-sample forecasts. We illustrate the models for various quarterly UK consumption
26 CFR 1.263A-12 - Production period.
2010-04-01
... production activities—(1) In general. The term physical production activities includes any physical activity...) Incidental repairs. Physical activities of an incidental nature that may be treated as repairs under § 1.162... starting with the first measurement period that begins after the first day in which production ceases....
Information Model for Product Modeling
Institute of Scientific and Technical Information of China (English)
焦国方; 刘慎权
1992-01-01
The Key problems in product modeling for integrated CAD ∥CAM systems are the information structures and representations of products.They are taking more and more important roles in engineering applications.With the investigation on engineering product information and from the viewpoint of industrial process,in this paper,the information models are proposed and the definitions of the framework of product information are given.And then,the integration and the consistence of product information are discussed by introucing the entity and its instance.As a summary,the information structures described in this paper have many advantage and natures helpful in engineering design.
Cyclic Period in the CBE Model
Frampton, Paul H
2016-01-01
In a cyclic entropy model in which the extroverse is jettisoned at turnaround with a Come Back Empty (CBE) assumption, we address matching of the contaction scale factor $\\hat{a}(t)=f(t_T){a}(t)$ to the expansion scale factor $a(t)$, where $f(t_T)$ is the ratio at turnaround of the introverse to extroverse radii. Such matching is necessary for infinite cyclicity and fixes the CBE period at $\\sim 2.6Ty$.
A Multi Period Equilibrium Pricing Model
Pirvu, Traian A
2012-01-01
In this paper, we propose an equilibrium pricing model in a dynamic multi-period stochastic framework with uncertain income streams. In an incomplete market, there exist two traded risky assets (e.g. stock/commodity and weather derivative) and a non-traded underlying (e.g. temperature). The risk preferences are of exponential (CARA) type with a stochastic coefficient of risk aversion. Both time consistent and time inconsistent trading strategies are considered. We obtain the equilibriums prices of a contingent claim written on the risky asset and non-traded underlying. By running numerical experiments we examine how the equilibriums prices vary in response to changes in model parameters.
Basic relations for the period variation models of variable stars
Mikulášek, Zdeněk; Gráf, Tomáš; Zejda, Miloslav; Zhu, Liying; Qian, Shen-Bang
2012-01-01
Models of period variations are basic tools for period analyzes of variable stars. We introduce phase function and instant period and formulate basic relations and equations among them. Some simple period models are also presented.
允许重新进货情况下单周期可替代产品的库存模型%Single-period Two-product Inventory Model with Reorder and Substitution
Institute of Scientific and Technical Information of China (English)
李小申; 高克权
2006-01-01
In market, excess demands for many products can be met by reorder even during one period, and retailers usually adopt substitution strategy for more benefit. Under the retailer's substitution strategy and permission of reorder, we develop the profits maximization model for the two-substitutable-product inventory problem with stochastic demands and proportional costs and revenues. We show that the objective function is concave and submodular, and therefore the optimal policy exists. We present the optimal conditions for order quantity and provide some properties of the optimal order quantities. Comparing our model with Netessine and Rudi's, we prove that reorder and adoption of the substitution strategy can raise the general profits and adjust down the general stock level.
A periodic pricing model considering reference effect
Directory of Open Access Journals (Sweden)
Yang Hui
2016-01-01
Full Text Available The purpose of this paper is to investigate the optimal pricing strategies with reference effects in revenue management settings. We firstly propose a static pricing model with the properties of stochastic demand, finite horizon and fixed capacity, and prove the existence and uniqueness of the solution. Secondly, we extend the fixed pricing model to a periodic pricing model and incorporate a memory-based reference price in the demand function to investigate how the reference effect impacts on traditional revenue management decisions. We present numerical examples in both low demand situations and high demand situations for different levels of reference effects and different updating frequencies. The results show that the dynamic pricing strategies are superior to a static one even when reference effects are taken into consideration. We also provide some manage-rial insights including pricing directions, pricing dispersion and the optimal updating frequency for both demand situations.
DEFF Research Database (Denmark)
Cameron, Ian T.; Gani, Rafiqul
This book covers the area of product and process modelling via a case study approach. It addresses a wide range of modelling applications with emphasis on modelling methodology and the subsequent in-depth analysis of mathematical models to gain insight via structural aspects of the models. These ...
DEFF Research Database (Denmark)
Pedersen, Rasmus
on the notion that reuse and encapsulation of platform elements are fundamental characteristics of a product platform. Reuse covers the desire to reuse and share certain assets across a family of products and/or across generations of products. Product design solutions and principles are often regarded...... as important assets in a product platform, yet activities, working patterns, processes and knowledge can also be reused in a platform approach. Encapsulation is seen as a process in which the different elements of a platform are grouped into well defined and self-contained units which are decoupled from each......This PhD thesis has the title Product Platform Modelling. The thesis is about product platforms and visual product platform modelling. Product platforms have gained an increasing attention in industry and academia in the past decade. The reasons are many, yet the increasing globalisation...
DEFF Research Database (Denmark)
Cameron, Ian T.; Gani, Rafiqul
This book covers the area of product and process modelling via a case study approach. It addresses a wide range of modelling applications with emphasis on modelling methodology and the subsequent in-depth analysis of mathematical models to gain insight via structural aspects of the models....... These approaches are put into the context of life cycle modelling, where multiscale and multiform modelling is increasingly prevalent in the 21st century. The book commences with a discussion of modern product and process modelling theory and practice followed by a series of case studies drawn from a variety...... to biotechnology applications, food, polymer and human health application areas. The book highlights to important nature of modern product and process modelling in the decision making processes across the life cycle. As such it provides an important resource for students, researchers and industrial practitioners....
Mott transitions in the periodic Anderson model
Logan, David E.; Galpin, Martin R.; Mannouch, Jonathan
2016-11-01
The periodic Anderson model (PAM) is studied within the framework of dynamical mean-field theory, with particular emphasis on the interaction-driven Mott transition it contains, and on resultant Mott insulators of both Mott-Hubbard and charge-transfer type. The form of the PAM phase diagram is first deduced on general grounds using two exact results, over the full range of model parameters and including metallic, Mott, Kondo and band insulator phases. The effective low-energy model which describes the PAM in the vicinity of a Mott transition is then shown to be a one-band Hubbard model, with effective hoppings that are not in general solely nearest neighbour, but decay exponentially with distance. This mapping is shown to have a range of implications for the physics of the problem, from phase boundaries to single-particle dynamics; all of which are confirmed and supplemented by NRG calculations. Finally we consider the locally degenerate, non-Fermi liquid Mott insulator, to describe which requires a two-self-energy description. This is shown to yield a number of exact results for the associated local moment, charge, and interaction-renormalised levels, together with a generalisation of Luttinger’s theorem to the Mott insulator.
Directory of Open Access Journals (Sweden)
Alberto Herrán
2011-01-01
Full Text Available A multiproduct pipeline provides an economic way to transport large volumes of refined petroleum products over long distances. In such a pipeline, different products are pumped back−to−back without any separation device between them. The sequence and lengths of such pumping runs must be carefully selected in order to meet market demands while minimizing pipeline operational costs and satisfying several constraints. The production planning and scheduling of the products at the refinery must also be synchronized with the transportation in order to avoid the usage of the system at some peak−hour time intervals. In this paper, we propose a multi−period mixed integer nonlinear programming (MINLP model for an optimal planning and scheduling of the production and transportation of multiple petroleum products from a refinery plant connected to several depots through a single pipeline system. The objective of this work is to generalize the mixed integer linear programming (MILP formulation proposed by Cafaro and Cerdá (2004, Computers and Chemical Engineering where only a single planning period was considered and the production planning and scheduling was not part of the decision process. Numerical examples show how the use of a single period model for a given time period may lead to infeasible solutions when it is used for the upcoming periods. These examples also show how integrating production planning with the transportation and the use of a multi−period model may result in a cost saving compared to using a single−period model for each period, independently.
A Three-period Samuelson-Diamond Growth Model
DEFF Research Database (Denmark)
Blomgren-Hansen, Niels
2005-01-01
Samuelson (1958) analyses a three-period model, whereas Diamod (1965) considers a two-period model. This difference poses the question whether the insights derived by analysing the simple two-period model carry over in the more complicated three-period case. They do. The Samuelson model (no...
Speiser, Bob; Walter, Chuck
2011-01-01
This paper explores how models can support productive thinking. For us a model is a "thing", a tool to help make sense of something. We restrict attention to specific models for whole-number multiplication, hence the wording of the title. They support evolving thinking in large measure through the ways their users redesign them. They assume new…
A model for optimizing the production of pharmaceutical products
Directory of Open Access Journals (Sweden)
Nevena Gospodinova
2017-05-01
Full Text Available The problem associated with the optimal production planning is especially relevant in modern industrial enterprises. The most commonly used optimality criteria in this context are: maximizing the total profit; minimizing the cost per unit of production; maximizing the capacity utilization; minimizing the total production costs. This article aims to explore the possibility for optimizing the production of pharmaceutical products through the construction of a mathematical model that can be viewed in two ways – as a single-product model and a multi-product model. As an optimality criterion it is set the minimization of the cost per unit of production for a given planning period. The author proposes an analytical method for solving the nonlinear optimization problem. An optimal production plan of Tylosin tartrate is found using the single-product model.
Modelling Retail Floorspace Productivity
A.R. Thurik (Roy); P. Kooiman
1986-01-01
textabstractThis research note presents a "switching regime" model to investigate the impact of environmental factors on floorspace productivity of individual retail stores. The model includes independent supply and demand functions, which are incorporated within a sales maximizing framework. Unlike
Modeling of laser induced periodic surface structures
Skolski, J.Z.P.; Römer, G.R.B.E.; Huis in 't Veld, A.J.; Mitko, V.S.; Obona, J.V.; Ocelik, V.; Hosson, J.T.M. de
2010-01-01
In surfaces irradiated by short laser pulses, Laser Induced Periodic Surface Structures (LIPSS) have been observed on all kind of materials for over forty years. These LIPSS, also referred to as ripples, consist of wavy surfaces with periodicity equal or smaller than the wavelength of the laser radi
GLOBAL ATTRACTIVITY IN A PERIODIC DELAY SINGLE SPECIES MODEL
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
In this paper, we establish the existence of a positive periodic solution for a periodic delay single species population growth model, and obtain sufficient conditions for the periodic solution to be globally attractive.
Accounting for the waterless period of oil production in calculations on oil field production design
Energy Technology Data Exchange (ETDEWEB)
Aminov, M.F.; Butorin, O.I.
1981-01-01
Formulae on the dynamics of oil and liquid from a methodology developed by the Tatar Scientific-Research and Design Institute for the Oil Industry are adjusted, accounting for the waterless period in oil production. It is demonstrated that the process of accounting for the waterless period in oil production leads to a more accurate prediction of the engineering parameters for mining and oil field.
Larson, Kathleen G.; Long, George R.; Briggs, Michael W.
2012-01-01
The mental models of both novice and advanced chemistry students were observed while the students performed a periodic table activity. The mental model framework seems to be an effective way of analyzing student behavior during learning activities. The analysis suggests that students do not recognize periodic trends through the examination of…
A time-periodic reaction-diffusion epidemic model with infection period
Zhang, Liang; Wang, Zhi-Cheng
2016-10-01
In this paper, we propose a time-periodic and diffusive SIR epidemic model with constant infection period. By introducing the basic reproduction number R_0 via a next generation operator for this model, we show that the disease goes extinction if R_0 1.
Larson, Kathleen G.; Long, George R.; Briggs, Michael W.
2012-01-01
The mental models of both novice and advanced chemistry students were observed while the students performed a periodic table activity. The mental model framework seems to be an effective way of analyzing student behavior during learning activities. The analysis suggests that students do not recognize periodic trends through the examination of…
Institute of Scientific and Technical Information of China (English)
刘思婧; 张锦; 李国旗
2012-01-01
为解决快速时尚品在成熟期网络销售过程中的物流节点选址与分配问题,以分销网络收益最大化作为决策目标,考虑销售策略及提前期约束的影响,构建了由4个参与方和4层物流设施构成的快速时尚品物流分销网络的多周期非线性混合整数规划模型,并采用遗传算法确定产品折扣率以及中央仓库、第三方物流企业和自取点的选址、分配及服务方案.算例结果表明:当折扣率为0.687时,物流分销网络总收益最大；当集货期大于等于2d时,物流分销网络总收益的增长率迅速减小.%In order to solve the logistics network location-allocation problem of fast fashion products in mature period of e-commerce retailing, a multi-period non-liner mixed integer programming model was proposed for the fast fashion products' logistics distribution network consisting of four parties and four layers. In this model, the maximization of profit is taken as the optimization objective, sales strategy and controllable lead time are taken into account, and the genetic algorithm is adopted to achieve the discount rate and the locations, allocations and service plans of warehouses, third party logistics enterprises and pickup spots. The case study results illustrate that when the discount rate is 0.687, the total profit of a logistics distribution network reaches the maximum value, and when the gathering time is not less than 2 d, the growth rate of the total profit decreases rapidly.
Product Development Process Modeling
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
The use of Concurrent Engineering and other modern methods of product development and maintenance require that a large number of time-overlapped "processes" be performed by many people. However, successfully describing and optimizing these processes are becoming even more difficult to achieve. The perspective of industrial process theory (the definition of process) and the perspective of process implementation (process transition, accumulation, and inter-operations between processes) are used to survey the method used to build one base model (multi-view) process model.
Periodic Integration: Further Results on Model Selection and Forecasting
Ph.H.B.F. Franses (Philip Hans); R. Paap (Richard)
1996-01-01
textabstractThis paper considers model selection and forecasting issues in two closely related models for nonstationary periodic autoregressive time series [PAR]. Periodically integrated seasonal time series [PIAR] need a periodic differencing filter to remove the stochastic trend. On the other
The Discrete Beverton-Holt Model with Periodic Harvesting in a Periodically Fluctuating Environment
Directory of Open Access Journals (Sweden)
Ziyad AlSharawi
2010-01-01
Full Text Available We investigate the effect of constant and periodic harvesting on the Beverton-Holt model in a periodically fluctuating environment. We show that in a periodically fluctuating environment, periodic harvesting gives a better maximum sustainable yield compared to constant harvesting. However, if one can also fix the environment, then constant harvesting in a constant environment can be a better option, especially for sufficiently large initial populations. Also, we investigate the combinatorial structure of the periodic sequence of carrying capacities and its effect on the maximum sustainable yield. Finally, we leave some questions worth further investigations.
Product Knowledge Modelling and Management
DEFF Research Database (Denmark)
Zhang, Y.; MacCallum, K. J.; Duffy, Alex
1996-01-01
The term, Product Knowledge is used to refer to two related but distinct concepts; the knowledge of a specific product (Specific Product Knowledge) and the knowledge of a product domain (Product Domain Knowledge). Modelling and managing Product Knowlege is an essential part of carrying out design...... function-oriented design. Both Specific Product Knowledge and Product Domain Knowledge are modelled at two levels, a meta-model and an information-level.Following that, a computer-based scheme to manage the proposed product lknowledge models within a dynamically changing environment is presented....
Advanced Production Planning Models
Energy Technology Data Exchange (ETDEWEB)
JONES,DEAN A.; LAWTON,CRAIG R.; KJELDGAARD,EDWIN A.; WRIGHT,STEPHEN TROY; TURNQUIST,MARK A.; NOZICK,LINDA K.; LIST,GEORGE F.
2000-12-01
>This report describes the innovative modeling approach developed as a result of a 3-year Laboratory Directed Research and Development project. The overall goal of this project was to provide an effective suite of solvers for advanced production planning at facilities in the nuclear weapons complex (NWC). We focused our development activities on problems related to operations at the DOE's Pantex Plant. These types of scheduling problems appear in many contexts other than Pantex--both within the NWC (e.g., Neutron Generators) and in other commercial manufacturing settings. We successfully developed an innovative and effective solution strategy for these types of problems. We have tested this approach on actual data from Pantex, and from Org. 14000 (Neutron Generator production). This report focuses on the mathematical representation of the modeling approach and presents three representative studies using Pantex data. Results associated with the Neutron Generator facility will be published in a subsequent SAND report. The approach to task-based scheduling described here represents a significant addition to the literature for large-scale, realistic scheduling problems in a variety of production settings.
Product Knowledge Modelling and Management
DEFF Research Database (Denmark)
Zhang, Y.; MacCallum, K. J.; Duffy, Alex
1996-01-01
The term, Product Knowledge is used to refer to two related but distinct concepts; the knowledge of a specific product (Specific Product Knowledge) and the knowledge of a product domain (Product Domain Knowledge). Modelling and managing Product Knowlege is an essential part of carrying out design...... function-oriented design. Both Specific Product Knowledge and Product Domain Knowledge are modelled at two levels, a meta-model and an information-level.Following that, a computer-based scheme to manage the proposed product lknowledge models within a dynamically changing environment is presented........A scheme is presented in this paper to model, i.e. classify, structure and formalise the product knowledge for the purpose of supporting function-oriented design. The product design specification and four types of required attributes of a specific product have been identified to form the Specific Product...
Periodic solutions of nonautonomous differential systems modeling obesity population
Energy Technology Data Exchange (ETDEWEB)
Arenas, Abraham J. [Departamento de Matematicas y Estadistica, Universidad de Cordoba Monteria (Colombia)], E-mail: aarenas@sinu.unicordoba.edu.co; Gonzalez-Parra, Gilberto [Departamento de Calculo, Universidad de los Andes, Merida (Venezuela, Bolivarian Republic of)], E-mail: gcarlos@ula.ve; Jodar, Lucas [Instituto de Matematica Multidisciplinar, Universidad Politecnica de Valencia Edificio 8G, 2o, 46022 Valencia (Spain)], E-mail: ljodar@imm.upv.es
2009-10-30
In this paper we study the periodic behaviour of the solutions of a nonautonomous model for obesity population. The mathematical model represented by a nonautonomous system of nonlinear ordinary differential equations is used to model the dynamics of obese populations. Numerical simulations suggest periodic behaviour of subpopulations solutions. Sufficient conditions which guarantee the existence of a periodic positive solution are obtained using a continuation theorem based on coincidence degree theory.
Modeling Periodic Impulsive Effects on Online TV Series Diffusion.
Fu, Peihua; Zhu, Anding; Fang, Qiwen; Wang, Xi
Online broadcasting substantially affects the production, distribution, and profit of TV series. In addition, online word-of-mouth significantly affects the diffusion of TV series. Because on-demand streaming rates are the most important factor that influences the earnings of online video suppliers, streaming statistics and forecasting trends are valuable. In this paper, we investigate the effects of periodic impulsive stimulation and pre-launch promotion on on-demand streaming dynamics. We consider imbalanced audience feverish distribution using an impulsive susceptible-infected-removed(SIR)-like model. In addition, we perform a correlation analysis of online buzz volume based on Baidu Index data. We propose a PI-SIR model to evolve audience dynamics and translate them into on-demand streaming fluctuations, which can be observed and comprehended by online video suppliers. Six South Korean TV series datasets are used to test the model. We develop a coarse-to-fine two-step fitting scheme to estimate the model parameters, first by fitting inter-period accumulation and then by fitting inner-period feverish distribution. We find that audience members display similar viewing habits. That is, they seek new episodes every update day but fade away. This outcome means that impulsive intensity plays a crucial role in on-demand streaming diffusion. In addition, the initial audience size and online buzz are significant factors. On-demand streaming fluctuation is highly correlated with online buzz fluctuation. To stimulate audience attention and interpersonal diffusion, it is worthwhile to invest in promotion near update days. Strong pre-launch promotion is also a good marketing tool to improve overall performance. It is not advisable for online video providers to promote several popular TV series on the same update day. Inter-period accumulation is a feasible forecasting tool to predict the future trend of the on-demand streaming amount. The buzz in public social communities
Return handling options and order quantities for single period products
D. Vlachos (Dimitrios); R. Dekker (Rommert)
2000-01-01
textabstractProducts which are sold through E-commerce or mail sales catalogues tend to have a much higher return rate than traditional products. The returns are especially problematic for seasonal products. To support decision making in these situations we study various options, which may be consid
MAXIMUM LIKELIHOOD ESTIMATION FOR PERIODIC AUTOREGRESSIVE MOVING AVERAGE MODELS.
Vecchia, A.V.
1985-01-01
A useful class of models for seasonal time series that cannot be filtered or standardized to achieve second-order stationarity is that of periodic autoregressive moving average (PARMA) models, which are extensions of ARMA models that allow periodic (seasonal) parameters. An approximation to the exact likelihood for Gaussian PARMA processes is developed, and a straightforward algorithm for its maximization is presented. The algorithm is tested on several periodic ARMA(1, 1) models through simulation studies and is compared to moment estimation via the seasonal Yule-Walker equations. Applicability of the technique is demonstrated through an analysis of a seasonal stream-flow series from the Rio Caroni River in Venezuela.
Parameter estimation of hidden periodic model in random fields
Institute of Scientific and Technical Information of China (English)
何书元
1999-01-01
Two-dimensional hidden periodic model is an important model in random fields. The model is used in the field of two-dimensional signal processing, prediction and spectral analysis. A method of estimating the parameters for the model is designed. The strong consistency of the estimators is proved.
Detecting Warming Hiatus Periods in CMIP5 Climate Model Projections
Li, Tony W.; Noel C. Baker
2016-01-01
The observed slow-down in the global-mean surface temperature (GST) warming from 1998 to 2012 has been called a “warming hiatus.” Certain climate models, operating under experiments which simulate warming by increasing radiative forcing, have been shown to reproduce periods which resemble the observed hiatus. The present study provides a comprehensive analysis of 38 CMIP5 climate models to provide further evidence that models produce warming hiatus periods during warming experiments. GST rate...
Modeling Novo Nordisk Production Systems
DEFF Research Database (Denmark)
Miller, Thomas Dedenroth
1997-01-01
This report describes attributes of models and systems, and how models can be used for description of production systems. There are special attention on the 'Theory of Domains'.......This report describes attributes of models and systems, and how models can be used for description of production systems. There are special attention on the 'Theory of Domains'....
Detecting Warming Hiatus Periods in CMIP5 Climate Model Projections
Directory of Open Access Journals (Sweden)
Tony W. Li
2016-01-01
Full Text Available The observed slow-down in the global-mean surface temperature (GST warming from 1998 to 2012 has been called a “warming hiatus.” Certain climate models, operating under experiments which simulate warming by increasing radiative forcing, have been shown to reproduce periods which resemble the observed hiatus. The present study provides a comprehensive analysis of 38 CMIP5 climate models to provide further evidence that models produce warming hiatus periods during warming experiments. GST rates are simulated in each model for the 21st century using two experiments: a moderate warming scenario (RCP4.5 and high-end scenario (RCP8.5. Warming hiatus periods are identified in model simulations by detecting (1 ≥15-year periods lacking a statistically meaningful trend and (2 rapid changes in the GST rate which resemble the observed 1998–2012 hiatus. Under the RCP4.5 experiment, all tested models produce warming hiatus periods. However, once radiative forcing exceeds 5 W/m2—about 2°C GST increase—as simulated in the RCP8.5 experiment after 2050, nearly all models produce only positive warming trends. All models show evidence of rapid changes in the GST rate resembling the observed hiatus, showing that the climate variations associated with warming hiatus periods are still evident in the models, even under accelerated warming conditions.
Period doubling and Blazhko modulation in BL Herculis hydrodynamic models
Smolec, R
2012-01-01
We present the hydrodynamic BL Herculis-type models which display a long-term modulation of pulsation amplitudes and phases. The modulation is either strictly periodic or it is quasi-periodic, with the modulation period and modulation pattern varying from one cycle to the other. Such behaviour has not been observed in any BL Her variable so far, however, it is a common property of their lower luminosity siblings - RR Lyrae variables showing the Blazhko effect. These models provide a support for the recent mechanism proposed by Buchler & Kollath to explain this still mysterious phenomenon. In their model, a half-integer resonance that causes the period doubling effect, discovered recently in the Blazhko RR Lyrae stars, is responsible for the modulation of the pulsation as well. Although our models are more luminous than is appropriate for RR Lyrae stars, they clearly demonstrate, through direct hydrodynamic computation, that the mechanism can indeed be operational. Of great importance are models which show...
Pseudo almost periodic solutions for a Lasota-Wazewska model
Directory of Open Access Journals (Sweden)
Samira Rihani
2016-03-01
Full Text Available In this work, we consider a new model describing the survival of red blood cells in animals. Specifically, we study a class of Lasota-Wazewska equation with pseudo almost periodic varying environment and mixed delays. By using the Banach fixed point theorem and some inequality analysis, we find sufficient conditions for the existence, uniqueness and stability of solutions. We generalize some results known for one type of delay and for the Lasota-Wazewska model with almost periodic and periodic coefficients. An example illustrates the proposed model.
Bayesian Age-Period-Cohort Modeling and Prediction - BAMP
Directory of Open Access Journals (Sweden)
Volker J. Schmid
2007-10-01
Full Text Available The software package BAMP provides a method of analyzing incidence or mortality data on the Lexis diagram, using a Bayesian version of an age-period-cohort model. A hierarchical model is assumed with a binomial model in the first-stage. As smoothing priors for the age, period and cohort parameters random walks of first and second order, with and without an additional unstructured component are available. Unstructured heterogeneity can also be included in the model. In order to evaluate the model fit, posterior deviance, DIC and predictive deviances are computed. By projecting the random walk prior into the future, future death rates can be predicted.
Institute of Scientific and Technical Information of China (English)
YaoZhijian
2005-01-01
In this paper, a two-species nonautonomous competitive model with stage structure and harvesting is considered. Sufficient conditions for the existence, uniqueness, global attractivity of positive periodic solution and the existence, uniform asvmntotic stability of almost neriodic solution are obtained.
Log-periodic behavior in a forest-fire model
Directory of Open Access Journals (Sweden)
B. D. Malamud
2005-01-01
Full Text Available This paper explores log-periodicity in a forest-fire cellular-automata model. At each time step of this model a tree is dropped on a randomly chosen site; if the site is unoccupied, the tree is planted. Then, for a given sparking frequency, matches are dropped on a randomly chosen site; if the site is occupied by a tree, the tree ignites and an 'instantaneous' model fire consumes that tree and all adjacent trees. The resultant frequency-area distribution for the small and medium model fires is a power-law. However, if we consider very small sparking frequencies, the large model fires that span the square grid are dominant, and we find that the peaks in the frequency-area distribution of these large fires satisfy log-periodic scaling to a good approximation. This behavior can be examined using a simple mean-field model, where in time, the density of trees on the grid exponentially approaches unity. This exponential behavior coupled with a periodic or near-periodic sparking frequency also generates a sequence of peaks in the frequency-area distribution of large fires that satisfy log-periodic scaling. We conclude that the forest-fire model might provide a relatively simple explanation for the log-periodic behavior often seen in nature.
DEFF Research Database (Denmark)
Sørensen, J.T.; Enevoldsen, Carsten; Kristensen, T.
1993-01-01
A range of preplanned dry period lengths in a dairy herd was evaluated, at different culling strategies and feeding regimes, by means of a dynamic stochastic model simulating the production at herd level. Dry period lengths were studied in the range of 4 to 10 weeks. The culling strategies exhibi...
Unstable periodic orbits and attractor of the barotropic ocean model
Directory of Open Access Journals (Sweden)
E. Kazantsev
1998-01-01
Full Text Available A numerical method for detection of unstable periodic orbits on attractors of nonlinear models is proposed. The method requires similar techniques to data assimilation. This fact facilitates its implementation for geophysical models. This method was used to find numerically several low-period orbits for the barotropic ocean model in a square. Some numerical particularities of application of this method are discussed. Knowledge of periodic orbits of the model helps to explain some of these features like bimodality of probability density functions (PDF of principal parameters. These PDFs have been reconstructed as weighted averages of periodic orbits with weights proportional to the period of the orbit and inversely proportional to the sum of positive Lyapunov exponents. The fraction of time spent in the vicinity of each periodic orbit has been compared with its instability characteristics. The relationship between these values shows the 93% correlation. The attractor dimension of the model has also been approximated as a weighted average of local attractor dimensions in vicinities of periodic orbits.
PRODUCT STRUCTURE DIGITAL MODEL
Directory of Open Access Journals (Sweden)
V.M. Sineglazov
2005-02-01
Full Text Available Research results of representation of product structure made by means of CADDS5 computer-aided design (CAD system, Product Data Management Optegra (PDM system and Product Life Cycle Management Wind-chill system (PLM, are examined in this work. Analysis of structure component development and its storage in various systems is carried out. Algorithms of structure transformation required for correct representation of the structure are considered. Management analysis of electronic mockup presentation of the product structure is carried out for Windchill system.
Mathematically guided approaches to distinguish models of periodic patterning
2015-01-01
How periodic patterns are generated is an open question. A number of mechanisms have been proposed – most famously, Turing's reaction-diffusion model. However, many theoretical and experimental studies focus on the Turing mechanism while ignoring other possible mechanisms. Here, we use a general model of periodic patterning to show that different types of mechanism (molecular, cellular, mechanical) can generate qualitatively similar final patterns. Observation of final patterns is therefore n...
Periodic Solutions of a Model of Mitosis in Frog Eggs
Institute of Scientific and Technical Information of China (English)
Bei-ye Feng; Zuo-huan Zheng
2002-01-01
In this paper,we discuss a simplified model of mitosis in frog eggs proposed by M.T. Borisuk and J.J.Tyson in [1]. By using rigorous qualitative analysis, we prove the existence of the periodic solutions on a large scale and present the space region of the periodic solutions and the parameter region coresponding to the periodic solution. We also present the space region and the parameter region where there are no periodic solutions. The results are in accordance with the numerical results in [1] up to the qualitative property.
Kronig-Penney model for periodically segmented waveguides.
Stancil, D D
1996-08-20
Physical insight into the propagation characteristics of periodically segmented waveguides can be obtained by viewing the guiding layer as a thin slab of an idealized infinite medium with periodic layers along the direction of propagation. One can analyze the properties of this infinite medium using a formal analogy with the Kronig-Penney model used to describe the propagation of electron wave functions in a periodic crystal potential. The model correctly gives the effective refractive index of the layer, gives insight into the electric field profiles at different points on the dispersion curve, and leads to a qualitative explanation of why the optical loss diminishes at both large and small duty cycles.
Model-Corrected Microwave Imaging through Periodic Wall Structures
Directory of Open Access Journals (Sweden)
Paul C. Chang
2012-01-01
Full Text Available A model-based imaging framework is applied to correct the target distortion seen in microwave imaging through a periodic wall structure. In addition to propagation delays caused by the wall, it is shown that the structural periodicity induces high-order space harmonics leading to other ghost artifacts in the through-wall image. To overcome these distortions, the periodic layer Green’s function is incorporated into the forward model. A linear back-projection solution and a nonlinear minimization solution are applied to solve the inverse problem. The model-based back-projection image corrects the distortion and has higher resolution compared with free space due to the inclusion of multipath propagation through the periodic wall, but considerable sidelobe clutter is present. The nonlinear solution not only corrects target distortion without clutter but also reduces the solution to a sparse form.
The investigation of the electronic structure of periodic and non-periodic collagen models
Bakhshi, A. K.; Paterlini, G.; Némethy, G.; Ladik, J.
1993-05-01
Collagen is a protein which is not periodic, but its sequence still has some well defined regularities. We have performed model investigation for the electronic structure of this protein which is one of the few native polypeptides which does not possess a nearly random sequence (intermediate case between periodic polypeptides and polypeptides with random sequences). The total electron density of states has been determined for model polypeptide chains of the type I collagen triple helix, with priodic and aperiodic amino sequences. Calculations have been performed using the negative factor counting technique in its ab initio Hartree—Fock matrix block form. The well-known sequence regularities of collagen have been taken into account, in order to simplify the model calculations. Beside glycine, proline, hydroxyproline and alanine, only the next two most frequently occurring amino acid residues (glutamine and arginine) have been incorporated in the sequences. The conformation of the polypeptide chain was that occurring in the collagen triple helix. It has been taken from previous empirical potential energy calculations of collagen-like model triple helices by Némethy and Scheraga. The density of state histograms for the periodic polypeptide chains show only very narrow peaks in both the valence and conduction bands attributable to the sequence regularities, while the aperiodic chains exhibit both narrow peaks and broader allowed regions in both bands. In other words, the electronic structure of the aperiodic model chains investigated falls between those for periodic and completely random polypeptides. The results are discussed in terms of the general regularities of the collagen sequence.
Queuing Network Modeling of the Psychological Refractory Period (PRP)
Wu, Changxu; Liu, Yili
2008-01-01
The psychological refractory period (PRP) is a basic but important form of dual-task information processing. Existing serial or parallel processing models of PRP have successfully accounted for a variety of PRP phenomena; however, each also encounters at least 1 experimental counterexample to its predictions or modeling mechanisms. This article…
ON THE EDDY VISCOSITY MODEL OF PERIODIC TURBULENT SHEAR FLOWS
Institute of Scientific and Technical Information of China (English)
王新军; 罗纪生; 周恒
2003-01-01
Physical argument shows that eddy viscosity is essentially different from molecular viscosity. By direct numerical simulation, it was shown that for periodic turbulent flows, there is phase difference between Reynolds stress and rate of strain. This finding posed great challenge to turbulence modeling, because most turbulence modeling, which use the idea of eddy viscosity, do not take this effect into account.
Two-echelon competitive integrated supply chain model with price and credit period dependent demand
Pal, Brojeswar; Sankar Sana, Shib; Chaudhuri, Kripasindhu
2016-04-01
This study considers a two-echelon competitive supply chain consisting of two rivaling retailers and one common supplier with trade credit policy. The retailers hope that they can enhance their market demand by offering a credit period to the customers and the supplier also offers a credit period to the retailers. We assume that the market demand of the products of one retailer depends not only on their own market price and offering a credit period to the customers, but also on the market price and offering a credit period of the other retailer. The supplier supplies the product with a common wholesale price and offers the same credit period to the retailers. We study the model under a centralised (integrated) case and a decentralised (Vertical Nash) case and compare them numerically. Finally, we investigate the model by the collected numerical data.
Periodic and homoclinic orbits in a toy climate model
Directory of Open Access Journals (Sweden)
M. Toner
1994-01-01
Full Text Available A two dimensional system of autonomous nonlinear ordinary differential equations models glacier growth and temperature changes on an idealized planet. We apply standard perturbative techniques from dynamical systems theory to study small amplitude periodic orbits about a constant equilibrium. The equations are put in cononical form and the local phase space topology is examined. Maximum and minimum periods of oscillation are obtained and related to the radius of the orbit. An adjacent equilibrium is shown to have saddle character and the inflowing and outflowing manifolds of this saddle are studied using numerical integration. The inflowing manifolds show the region of attraction for the periodic orbit. As the frequency gets small, the adjacent (saddle equilibrium approaches the radius of the periodic orbit. The bifurcation of the periodic orbit to a stable homoclinic orbit is observed when an inflowing manifold and an outflowing manifold of the adjacent equilibrium cross.
Stability of GOY Model Under Modulation of Periodic External Force
Institute of Scientific and Technical Information of China (English)
ZHAO Ying-Kui; CHEN Shi-Gang; WANG Guang-Rui
2008-01-01
There is a phase transition between quasi-periodic state and intermittent chaos in GOY model with a critical value δ0. When we add a modulated periodic external force to the system, the phase transition can also be found with a critical value δe. Due to coupling between the force and the intrinsic fluctuation of the velocity on shells in GOY model, the stability of the system has been changed, which results in the variation of the critical value. For proper intensity and period of the force, δe is unequal to δ0. The critical value is a nonlinear function of amplitude of the force, and the fluctuation of the velocity can resonate with the external force for certain period Te.
Periodicity and blowup in a two-species cooperating model
DEFF Research Database (Denmark)
Lin, Zhigui; Liu, Jiahong; Pedersen, Michael
2011-01-01
In this paper, the cooperating two-species Lotka–Volterra model is discussed. The existence and asymptotic behavior of T -periodic solutions for the periodic reaction diffusion system under homogeneous Dirichlet boundary conditions are first investigated. The blowup properties of solutions...... for the same system are then given. It is shown that periodic solutions exist if the intra-specific competitions are strong whereas blowup solutions exist under certain conditions if the intra-specific competitions are weak. Numerical simulations and a brief discussion are also presented in the last section....
Periodic migration in a physical model of cells on micropatterns
Camley, Brian A.; Zhao, Yanxiang; Li, Bo; Levine, Herbert; Rappel, Wouter-Jan
2013-01-01
We extend a model for the morphology and dynamics of a crawling eukaryotic cell to describe cells on micropatterned substrates. This model couples cell morphology, adhesion, and cytoskeletal flow in response to active stresses induced by actin and myosin. We propose that protrusive stresses are only generated where the cell adheres, leading to the cell's effective confinement to the pattern. Consistent with experimental results, simulated cells exhibit a broad range of behaviors, including steady motion, turning, bipedal motion, and periodic migration, in which the cell crawls persistently in one direction before reversing periodically. We show that periodic motion emerges naturally from the coupling of cell polarization to cell shape by reducing the model to a simplified one-dimensional form that can be understood analytically. PMID:24160631
HP Memristor mathematical model for periodic signals and DC
Radwan, Ahmed G.
2012-07-28
In this paper mathematical models of the HP Memristor for DC and periodic signal inputs are provided. The need for a rigid model for the Memristor using conventional current and voltage quantities is essential for the development of many promising Memristors\\' applications. Unlike the previous works, which focuses on the sinusoidal input waveform, we derived rules for any periodic signals in general in terms of voltage and current. Square and triangle waveforms are studied explicitly, extending the formulas for any general square wave. The limiting conditions for saturation are also provided in case of either DC or periodic signals. The derived equations are compared to the SPICE model of the Memristor showing a perfect match.
Reliable multi period multi product supply chain design with facility disruption
Directory of Open Access Journals (Sweden)
Mehdi Rafiei
2013-04-01
Full Text Available This paper presents a strategic multi segment, multi period and multi-product supply chain management to meet reliable networks for handling disruptions strike. We present a mixed-integer programming model whose objective is to minimize the expected cost composed of probability and cost of occurrence in each scenario. The proposed model of this paper considers time value of money for each operation and transportation cost. We attempt to minimize expected costs by considering the levels of inventory, back-ordering, the available machine capacity and labor levels for each source, transportation capacity at each transshipment node and available warehouse space at each destination. The problem is generalized by taking into account backup supplier with reserved capacity and backup transshipment node that, which satisfies demands at higher price without disruption facility. We use a priority-based genetic algorithms encoding to solve the proposed problem under multi period and multi product conditions. The performance of the proposed model is examined using some instances.
Groundwater flow modelling of periods with temperate climate conditions - Forsmark
Energy Technology Data Exchange (ETDEWEB)
Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Swan, David (Serco Technical Consulting Services (United Kingdom)); Marsic, Niko (Kemakta Konsult AB (Sweden)); Follin, Sven (SF GeoLogic AB (Sweden))
2010-11-15
As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different climate conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Forsmark site during temperate conditions; i.e. from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 12,000 AD. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a hydrogeological base case (reference case conceptualisation) and then in an examination of various areas of uncertainty within the current understanding by a series of model variants. The hydrogeological base case models at three different scales, 'repository', 'site' and 'regional', make use of continuous porous medium (CPM), equivalent continuous porous medium (ECPM) and discrete fracture network (DFN) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events
Risk Modelling of Agricultural Products
Nugrahani, E. H.
2017-03-01
In the real world market, agricultural commodity are imposed with fluctuating prices. This means that the price of agricultural products are relatively volatile, which means that agricultural business is a quite risky business for farmers. This paper presents some mathematical models to model such risks in the form of its volatility, based on certain assumptions. The proposed models are time varying volatility model, as well as time varying volatility with mean reversion and with seasonal mean equation models. Implementation on empirical data show that agricultural products are indeed risky.
Feature Technology in Product Modeling
Institute of Scientific and Technical Information of China (English)
ZHANG Xu; NING Ruxin
2006-01-01
A unified feature definition is proposed. Feature is form-concentrated, and can be used to model product functionalities, assembly relations, and part geometries. The feature model is given and a feature classification is introduced including functional, assembly, structural, and manufacturing features. A prototype modeling system is developed in Pro/ENGINEER that can define the assembly and user-defined form features.
An R package for fitting age, period and cohort models
Directory of Open Access Journals (Sweden)
Adriano Decarli
2014-11-01
Full Text Available In this paper we present the R implementation of a GLIM macro which fits age-period-cohort model following Osmond and Gardner. In addition to the estimates of the corresponding model, owing to the programming capability of R as an object oriented language, methods for printing, plotting and summarizing the results are provided. Furthermore, the researcher has fully access to the output of the main function (apc which returns all the models fitted within the function. It is so possible to critically evaluate the goodness of fit of the resulting model.
Forecasting demand for single-period products : A case study in the apparel industry
Mostard, Julien; Teunter, Ruud; de Koster, Rene
2011-01-01
The problem considered is that of forecasting demand for single-period products before the period starts. We study this problem for the case of a mail order apparel company that needs to order its products pre-season. The lack of historical demand data implies that other sources of data are needed.
Forecasting demand for single-period products : A case study in the apparel industry
Mostard, Julien; Teunter, Ruud; de Koster, Rene
2011-01-01
The problem considered is that of forecasting demand for single-period products before the period starts. We study this problem for the case of a mail order apparel company that needs to order its products pre-season. The lack of historical demand data implies that other sources of data are needed.
A Simple Discrete Model of Brownian Motors: Time-periodic Markov Chains
Ge, Hao; Jiang, Da-Quan; Qian, Min
2006-05-01
In this paper, we consider periodically inhomogeneous Markov chains, which can be regarded as a simple version of physical model—Brownian motors. We introduce for them the concepts of periodical reversibility, detailed balance, entropy production rate and circulation distribution. We prove the equivalence of the following statements: The time-periodic Markov chain is periodically reversible; It is in detailed balance; Kolmogorov's cycle condition is satisfied; Its entropy production rate vanishes; Every circuit and its reversed circuit have the same circulation weight. Hence, in our model of Markov chains, the directed transport phenomenon of Brownian motors, i.e. the existence of net circulation, can occur only in nonequilibrium and irreversible systems. Moreover, we verify the large deviation property and the Gallavotti-Cohen fluctuation theorem of sample entropy production rates of the Markov chain.
Groundwater flow modelling of periods with temperate climate conditions - Laxemar
Energy Technology Data Exchange (ETDEWEB)
Joyce, Steven; Simpson, Trevor; Hartley, Lee; Applegate, David; Hoek, Jaap; Jackson, Peter; Roberts, David; Swan, David (Serco Technical Consulting Services (United Kingdom)); Gylling, Bjoern; Marsic, Niko (Kemakta Konsult AB, Stockholm (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden))
2010-12-15
As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report concerns the modelling of a repository at the Laxemar-Simpevarp site during temperate climate conditions as a comparison to corresponding modelling carried out for Forsmark /Joyce et al. 2010/. The collation and implementation of onsite hydrogeological and hydrogeochemical data from previous reports are used in the construction of a Hydrogeological base case (reference case conceptualisation) and then an examination of various areas of uncertainty within the current understanding by a series of model variants. The Hydrogeological base case models at three different scales, 'repository', 'site' and 'regional' make use of a discrete fracture network (DFN) and equivalent continuous porous medium (ECPM) models. The use of hydrogeological models allow for the investigation of the groundwater flow from a deep disposal facility to the biosphere and for the calculation of performance measures that will provide an input to the site performance assessment. The focus of the study described in this report has been to perform numerical simulations of the hydrogeological system from post-closure and throughout the temperate period up until the receding shoreline leaves the modelling domain at around 15,000 AD. Besides providing quantitative results for the immediate temperate period following post-closure, these results are also intended to give a qualitative indication of the evolution of the groundwater system during future temperate periods within an ongoing cycle of glacial/inter-glacial events
MASS CUSTOMIZATION and PRODUCT MODELS
DEFF Research Database (Denmark)
Svensson, Carsten; Malis, Martin
2003-01-01
to the product. Through the application of a mass customization strategy, companies have a unique opportunity to create increased customer satisfaction. In a customized production, knowledge and information have to be easily accessible since every product is a unique combination of information. If the dream...... of a customized alternative instead of a uniform mass-produced product shall become a reality, then the cross-organizational efficiency must be kept at a competitive level. This is the real challenge for mass customization. A radical restructuring of both the internal and the external knowledge management systems......When dealing with complex product models, efficient knowledge distribution is essential to obtain success. This paper describes how product models can be applied to support the knowledge distribution. The change towards individualization will radically affect the knowledge application in relation...
A lumped model for rotational modes in periodic solid composites
Peng, Pai
2013-10-01
We present a lumped model to study the rotational modes in a type of two-dimensional periodic solid composites comprised of a square array of rubber-coated steel cylinders embedded in an epoxy matrix. The model captures the physical essence of rotational modes in such systems for various combinations of material parameters, and, therefore it is able to describe the transition behaviour when the system is gradually adjusted from an elastic metamaterial to an elastic phononic crystal. From the model, we can define a transition zone which separates the typical elastic metamaterials and the phononic crystals.
Pedroso, Adriana Ayres; Andrade, Maria Auxiliadora; Café, Marcos Barcellos; Leandro, Nadja Susana M; Menten, José Fernando M; Stringhini, José Henrique
2005-12-01
The initial eggs produced by broiler breeder hens are relatively small compared with later in the production cycle. An evaluation of indices related to hatchability is required when these eggs are to be used for the production of broiler chicks. Two experiments were conducted to evaluate characteristics related to the hatchability of eggs from pullet-to-breeder transition phase, at 25 and 27 weeks of age, and from the peak of production period and five weeks later, at 32 and 37 weeks of age. Eggs from birds 25 weeks had a lesser fertility in Experiment 1. Mortality occurred unevenly in early (1-5 days), middle (6-17 days) and late (18-21 days) incubation, and greater mortality was observed after the internal membrane was ruptured. The younger the hen, the lighter the egg, chick, and shell, and the longer the time required to complete the hatching process. In Experiment 2, greater mortalities were observed at the early period (1-5 days) and after "pipping" of the internal and external membranes. Embryos from heavy eggs of breeder hens 37 weeks of age took less time to complete the hatching process. Results indicated the larger the egg, the heavier the chick and shell, and the lesser the shell percentage. As breeder age advanced, characteristics related to egg fertility and hatchability improved.
Global stability, periodic solutions, and optimal control in a nonlinear differential delay model
Directory of Open Access Journals (Sweden)
Anatoli F. Ivanov
2010-09-01
Full Text Available A nonlinear differential equation with delay serving as a mathematical model of several applied problems is considered. Sufficient conditions for the global asymptotic stability and for the existence of periodic solutions are given. Two particular applications are treated in detail. The first one is a blood cell production model by Mackey, for which new periodicity criteria are derived. The second application is a modified economic model with delay due to Ramsey. An optimization problem for a maximal consumption is stated and solved for the latter.
Positive Periodic Solutions of an Epidemic Model with Seasonality
Directory of Open Access Journals (Sweden)
Gui-Quan Sun
2013-01-01
Full Text Available An SEI autonomous model with logistic growth rate and its corresponding nonautonomous model are investigated. For the autonomous case, we give the attractive regions of equilibria and perform some numerical simulations. Basic demographic reproduction number Rd is obtained. Moreover, only the basic reproduction number R0 cannot ensure the existence of the positive equilibrium, which needs additional condition Rd>R1. For the nonautonomous case, by introducing the basic reproduction number defined by the spectral radius, we study the uniform persistence and extinction of the disease. The results show that for the periodic system the basic reproduction number is more accurate than the average reproduction number.
Product models for the Construction industry
DEFF Research Database (Denmark)
Sørensen, Lars Schiøtt
1996-01-01
Different types of product models for the building sector was elaborated and grouped. Some discussion on the different models was given. The "definition" of Product models was given.......Different types of product models for the building sector was elaborated and grouped. Some discussion on the different models was given. The "definition" of Product models was given....
Izhar, Ahmad; Tariq, Masood
2009-01-01
Abstract The study attempts to assess the impact of institutional credit on agriculture production by estimating Cobb Douglas agricultural production function for the pre reform (1972-91) and post reform (1992-2005) period in India using time series data. Study also analyses the trends and pattern of institutional credit during pre reform and post reform period. Annual average growth rate of institutional credit was lowest during the decade 1990-2000 and was highest during 1971-80. Institu...
Surface N Balances in Agricultural Crop Production Systems in China for the Period 1980-2015
Institute of Scientific and Technical Information of China (English)
SUN Bo; SHEN Run-Ping; A.F.BOUWMAN
2008-01-01
Surface nitrogen (N) balances for ChinEs crop production systems was estimated using statistical data collected from 1980 to 2004 at the national and provincial scale and from 1994 to 1999 at the county level.There was a surplus N balance throughout these periods,but the surplus was nearly stable in recent years.Projections using nonseasonal Box-Jenkins model or exponential models show that the N surplus for the total cultivated land in China was likely to increase from 142.8 kg ha-1 in 2004 to 168.6 kg ha-1 in 2015.The N balance surplus in the more developed southeastern provinces was the largest,and was slightly less in the central region,which caused the nitrate pollution in the ground water.The N surplus was much less in the western and northern provinces because of lower synthetic fertilizer inputs.The region with high N risk includes Beijing Municipality and Jiangsu,Zhejiang,Fujian,Guangdong,Hubei,and Shandong provinces for 2002-2004.The projections suggested that 15 provinces (or municipalities) in the middle and southeastern part of China except Jiangxi and Shanxi provinces would become the high-risk region by 2015.The level of economic development,transportation,and labor force condition had an important effect on the N balance surplus at the county level,but the last two factors showed remarkable impact at the provincial level.To decrease the nonpoint pollution (Npp) risk from crop production,the authors suggested to reduce the target level for national grain self-sufficiency to 90%-95% and change the regional structure of grain production by moving some of the future grain production from the high Npp risk areas of eastern China to parts of the central and western provinces where the Npp risk was much less.
Model of tunnelling through periodic array of quantum dots
Directory of Open Access Journals (Sweden)
Meynster Dmitry
2017-01-01
Full Text Available Several explicitly solvable models of electron tunnelling in a system of single and double two-dimensional periodic arrays of quantum dots with two laterally coupled leads in a homogeneous magnetic field are constructed. First, a model of single layer formed by periodic array of zero-range potentials is described. The Landau operator (the Schrodinger operator with a magnetic field with point-like interactions is the system Hamiltonian. We deal with two types of the layer lattices: square and honeycomb. The periodicity condition gives one an invariance property for the Hamiltonian in respect to magnetic translations group. The consideration of double quantum layer reduces to the replacement of the basic cell for the single layer by a cell including centers of different layers. Two variants of themodel for the double layer are suggested: with direct tunneling between the layers and with the connecting channels (segments in the model between the layers. The theory of self-adjoint extensions of symmetric operators is a mathematical background of the model. The third stage of the construction is the description of leads connection. It is made by the operator extensions theory method too. Electron tunneling from input lead to the output lead through the double quantum layer is described. Energy ranges with extremely small (practically, zero transmission were found. Dependencies of the transmission coefficient (particularly, “zero transmission bands” positions on the magnetic field, the energy of electron and the distance between layers are investigated. The results are compared with the corresponding single-layer transmission.
CHOKAN T.
2011-01-01
The comparative analysis of the milk chemical composition depending on milk productivity of Ukrainian Mountain Carpathian sheep during the pasture period were studied. It was found changes of milk composition (increasing of protein content, fat, dry matter and nutritive value) with a decrease of milk yield in the end period of lactation.
Multi products single machine EPQ model with immediate rework process
Directory of Open Access Journals (Sweden)
Jahangir Biabani
2012-01-01
Full Text Available This paper develops an economic production quantity (EPQ inventory model with rework process for a single stage production system with one machine. The existence of a unique machine results in limited production capacity. The aim of this research is to determine both the optimal cycle length and the optimal production quantity for each product to minimize the expected total cost (holding, production, setup, rework costs. The convexity of the inventory model is derived. Also the objective function is proved to be convex. The proposed inventory model is validated with illustrating numerical examples and the optimal period length and the total system cost are analyzed.
Optimization of the process of egg omelet production with fillings with extended storage period
Directory of Open Access Journals (Sweden)
V. Sukmanov
2015-05-01
Full Text Available Introduction. Optimization of the egg omelets (EO production using high pressure (HP will allow to produce a minimum cost product during manufacturing and also to obtain a product with high consumer properties. Materialsand methods. The concerned product is -EO -a mixture of liquid egg with grated or chopped cheese, xanthan gum, water or milk and spices. The EO manufacturing process consisted of packing the mixture in an airtight container with heating and processing in the high pressure installation. The EO suitability for long-term storage was evaluated by the "water activity" term. The EO quality was evaluated by an expert. There was used the undetermined Lagrange multipliers method to obtain the optimal process parameters. Results. As a result of the central composite rotatabel plan there was developed optimization model allowed to obtain the optimal EO HP processing parameters: pressure – 690 МPа, temperature –1220С, treatment duration –7×60s, 14g of water on 100 g of melange, 13 g of dry milk on 100 g of melange, xanthan gum content -0,75% of the total mixture mass, 25 g of cheese on 100 g of melange. These indicators allow to obtain the EO process parameters with the next indicators: water activity -0.704 and comprehensive quality Score - 0.98 that characterize the product as a product with high quality indicators stable over a long period of storage. The developed model analysis with using of Student's t test, Fisher dyspepsia and predicted optimization values calculation errors confirmed the reliability of the optimization parameters obtained values and the optimization model reliability. The calculations results for the given optimization parameters are presented as confidence intervals, confirming that their experimental values do not exceed the respective intervals and thus confirm the results authenticity . Conclusions. These results have practical significance and were adopted as the basis for the technical documentation
Lang, Carly; Fisher, Mandy; Neisa, Angelica; MacKinnon, Leona; Kuchta, Sandra; MacPherson, Susan; Probert, Adam; Arbuckle, Tye E
2016-01-06
Concern regarding the potential for developmental health risks associated with certain chemicals (e.g., phthalates, antibacterials) used in personal care products is well documented; however, current exposure data for pregnant women are limited. The objective of this study was to describe the pattern of personal care product use in pregnancy and the post-partum period. Usage patterns of personal care products were collected at six different time points during pregnancy and once in the postpartum period for a cohort of 80 pregnant women in Ottawa, Canada. The pattern of use was then described and groups of personal care product groups commonly used together were identified using hierarchical cluster analysis. The results showed that product use varied by income and country of birth. General hygiene products were the most commonly used products and were consistently used over time while cosmetic product use declined with advancing pregnancy and post-delivery. Hand soaps and baby products were reported as used more frequently after birth. This study is the first to track personal care product use across pregnancy and into the postpartum period, and suggests that pregnant populations may be a unique group of personal care product users. This information will be useful for exposure assessments.
Eccentric Exercise Program Design: A Periodization Model for Rehabilitation Applications.
Harris-Love, Michael O; Seamon, Bryant A; Gonzales, Tomas I; Hernandez, Haniel J; Pennington, Donte; Hoover, Brian M
2017-01-01
The applied use of eccentric muscle actions for physical rehabilitation may utilize the framework of periodization. This approach may facilitate the safe introduction of eccentric exercise and appropriate management of the workload progression. The purpose of this data-driven Hypothesis and Theory paper is to present a periodization model for isokinetic eccentric strengthening of older adults in an outpatient rehabilitation setting. Exemplar and group data are used to describe the initial eccentric exercise prescription, structured familiarization procedures, workload progression algorithm, and feasibility of the exercise regimen. Twenty-four men (61.8 ± 6.3 years of age) completed a 12-week isokinetic eccentric strengthening regimen involving the knee extensors. Feasibility and safety of the regimen was evaluated using serial visual analog scale (VAS, 0-10) values for self-reported pain, and examining changes in the magnitude of mean eccentric power as a function of movement velocity. Motor learning associated with the familiarization sessions was characterized through torque-time curve analysis. Total work was analyzed to identify relative training plateaus or diminished exercise capacity during the progressive phase of the macrocycle. Variability in the mean repetition interval decreased from 68 to 12% during the familiarization phase of the macrocycle. The mean VAS values were 2.9 ± 2.7 at the start of the regimen and 2.6 ± 2.9 following 12 weeks of eccentric strength training. During the progressive phase of the macrocycle, exercise workload increased from 70% of the estimated eccentric peak torque to 141% and total work increased by 185% during this training phase. The slope of the total work performed across the progressive phase of the macrocycle ranged from -5.5 to 29.6, with the lowest slope values occurring during microcycles 8 and 11. Also, mean power generation increased by 25% when eccentric isokinetic velocity increased from 60 to 90° s(-1) while
Eccentric Exercise Program Design: A Periodization Model for Rehabilitation Applications
Harris-Love, Michael O.; Seamon, Bryant A.; Gonzales, Tomas I.; Hernandez, Haniel J.; Pennington, Donte; Hoover, Brian M.
2017-01-01
The applied use of eccentric muscle actions for physical rehabilitation may utilize the framework of periodization. This approach may facilitate the safe introduction of eccentric exercise and appropriate management of the workload progression. The purpose of this data-driven Hypothesis and Theory paper is to present a periodization model for isokinetic eccentric strengthening of older adults in an outpatient rehabilitation setting. Exemplar and group data are used to describe the initial eccentric exercise prescription, structured familiarization procedures, workload progression algorithm, and feasibility of the exercise regimen. Twenty-four men (61.8 ± 6.3 years of age) completed a 12-week isokinetic eccentric strengthening regimen involving the knee extensors. Feasibility and safety of the regimen was evaluated using serial visual analog scale (VAS, 0–10) values for self-reported pain, and examining changes in the magnitude of mean eccentric power as a function of movement velocity. Motor learning associated with the familiarization sessions was characterized through torque-time curve analysis. Total work was analyzed to identify relative training plateaus or diminished exercise capacity during the progressive phase of the macrocycle. Variability in the mean repetition interval decreased from 68 to 12% during the familiarization phase of the macrocycle. The mean VAS values were 2.9 ± 2.7 at the start of the regimen and 2.6 ± 2.9 following 12 weeks of eccentric strength training. During the progressive phase of the macrocycle, exercise workload increased from 70% of the estimated eccentric peak torque to 141% and total work increased by 185% during this training phase. The slope of the total work performed across the progressive phase of the macrocycle ranged from −5.5 to 29.6, with the lowest slope values occurring during microcycles 8 and 11. Also, mean power generation increased by 25% when eccentric isokinetic velocity increased from 60 to 90° s−1
Product State Modelling based on a Meta Production
DEFF Research Database (Denmark)
Larsen, Michael Holm; Sørensen, Christian; Langer, Gilad
1999-01-01
) is a product model that contains continuously updated data regarding the outcome of the production processes. The main contribution of this paper is a definition and a description of a Production Meta Product State Model (Production Meta PSM), using the Unified Modelling Language (UML). The meta model......As products often deviate from their original design and specifications when being produced, adjustments of the product or process are required in order to meet specifications. A prerequisite for this adjustment, is appropriate and effectively collected shop floor data. The Product State Model (PSM...... incorporates a set of characteristics associated to the (1) scope or application domain of the PSM, (2) the artefact or product, and (3) the events transforming the product and trigging product state changes. Moreover, the paper provides guidelines for a specialisation of the meta model with respect...
Development of a production meta Product State Model
DEFF Research Database (Denmark)
Larsen, Michael Holm; Sørensen, Christian; Langer, Gilad
1999-01-01
) is a product model that contains continuously updated data regarding the outcome of the production processes. The main contribution of this paper is a definition and a description of a Production Meta Product State Model (Production Meta PSM), using the Unified Modelling Language (UML). The meta model......As products often deviate from their original design and specifications when being produced, adjustments of the product or process are required in order to meet specifications. A prerequisite for this adjustment, is appropriate and effectively collected shop floor data. The Product State Model (PSM...... incorporates a set of characteristics associated to the (1) scope or application domain of the PSM, (2) the artefact or product, and (3) the events transforming the product and trigging product state changes. Moreover, the paper provides guidelines for a specialisation of the meta model with respect...
Nitrogen flows in the food production chain of Hungary over the period 1961–2010
Hou, Yong; Ma, Lin; Sárdi, Katalin; Sisák, István; Ma, Wenqi
2015-01-01
Nitrogen (N) emissions from food production can cause serious environmental problems. Mitigation strategies require insights of N cycles in this complex system. A substance flow analysis for N in the Hungary food production and processing chain over the period 1961–2010 was conducted. Our results
Exact solutions to plaquette Ising models with free and periodic boundaries
Mueller, Marco; Johnston, Desmond A.; Janke, Wolfhard
2017-01-01
An anisotropic limit of the 3d plaquette Ising model, in which the plaquette couplings in one direction were set to zero, was solved for free boundary conditions by Suzuki (1972) [1], who later dubbed it the fuki-nuke, or "no-ceiling", model. Defining new spin variables as the product of nearest-neighbour spins transforms the Hamiltonian into that of a stack of (standard) 2d Ising models and reveals the planar nature of the magnetic order, which is also present in the fully isotropic 3d plaquette model. More recently, the solution of the fuki-nuke model was discussed for periodic boundary conditions, which require a different approach to defining the product spin transformation, by Castelnovo et al. (2010) [2]. We clarify the exact relation between partition functions with free and periodic boundary conditions expressed in terms of original and product spin variables for the 2d plaquette and 3d fuki-nuke models, noting that the differences are already present in the 1d Ising model. In addition, we solve the 2d plaquette Ising model with helical boundary conditions. The various exactly solved examples illustrate how correlations can be induced in finite systems as a consequence of the choice of boundary conditions.
Minimal model for short-time diffusion in periodic potentials.
Emary, Clive; Gernert, Robert; Klapp, Sabine H L
2012-12-01
We investigate the dynamics of a single, overdamped colloidal particle, which is driven by a constant force through a one-dimensional periodic potential. We focus on systems with large barrier heights where the lowest-order cumulants of the density field, that is, average position and the mean-squared displacement, show nontrivial (nondiffusive) short-time behavior characterized by the appearance of plateaus. We demonstrate that this "cage-like" dynamics can be well described by a discretized master equation model involving two states (related to two positions) within each potential valley. Nontrivial predictions of our approach include analytic expressions for the plateau heights and an estimate of the "de-caging time" obtained from the study of deviations from Gaussian behavior. The simplicity of our approach means that it offers a minimal model to describe the short-time behavior of systems with hindered dynamics.
Lifshitz Transitions in Magnetic Phases of the Periodic Anderson Model
Kubo, Katsunori
2015-09-01
We investigate the reconstruction of a Fermi surface, which is called a Lifshitz transition, in magnetically ordered phases of the periodic Anderson model on a square lattice with a finite Coulomb interaction between f electrons. We apply the variational Monte Carlo method to the model by using the Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, ferromagnetic, and charge-density-wave states. We find that an antiferromagnetic phase is realized around half-filling and a ferromagnetic phase is realized when the system is far away from half-filling. In both magnetic phases, Lifshitz transitions take place. By analyzing the electronic states, we conclude that the Lifshitz transitions to large ordered-moment states can be regarded as itinerant-localized transitions of the f electrons.
Evaluation of scientific periodicals and the Brazilian production of nursing articles.
Erdmann, Alacoque Lorenzini; Marziale, Maria Helena Palucci; Pedreira, Mavilde da Luz Gonçalves; Lana, Francisco Carlos Félix; Pagliuca, Lorita Marlena Freitag; Padilha, Maria Itayra; Fernandes, Josicelia Dumêt
2009-01-01
This study aimed to identify nursing journals edited in Brazil indexed in the main bibliographic databases in the areas of health and nursing. It also aimed to classify the production of nursing graduate programs in 2007 according to the QUALIS/CAPES criteria used to classify scientific periodicals that disseminate the intellectual production of graduate programs in Brazil. This exploratory study used data from reports and documents available from CAPES to map scientific production and from searching the main international and national indexing databases. The findings from this research can help students, professors and coordinators of graduate programs in several ways: to understand the criteria of classifying periodicals; to be aware of the current production of graduate programs in the area of nursing; and to provide information that authors can use to select periodicals in which to publish their articles.
Institute of Scientific and Technical Information of China (English)
ZHANG Qi; TI Wei; CAI Jiu-ju; DU Tao; WANG Ai-hua
2011-01-01
A mathematical model of optimal energy medium distribution in steelmaking process is formulated. In this model, three kinds of important energy mediums including byproduct gases, steam and electricity are considered, and the objective function accounts for both the change of generation and consumption of the byproduct gases and the demand of low （or middle） pressure steam and electricity for each period to maximize the benefit of products cost and minimize the consumption of energy. The results indicate that the optimal distribution scheme of byproduct gases, middle pressure steam, low pressure steam and electricity is achieved and case study shows that 6% of operation cost is reduced by using the proposed model comparing with the previous model.
Lithospheric Thickness Modeled from Long Period Surface Wave Dispersion
Energy Technology Data Exchange (ETDEWEB)
Pasyanos, M E
2008-05-15
The behavior of surface waves at long periods is indicative of subcrustal velocity structure. Using recently published dispersion models, we invert surface wave group velocities for lithospheric structure, including lithospheric thickness, over much of the Eastern Hemisphere, encompassing Eurasia, Africa, and the Indian Ocean. Thicker lithosphere under Precambrian shields and platforms are clearly observed, not only under the large cratons (West Africa, Congo, Baltic, Russia, Siberia, India), but also under smaller blocks like the Tarim Basin and Yangtze craton. In contrast, it is found that remobilized Precambrian structures like the Saharan Shield and Sino-Korean Paraplatform do not have well-established lithospheric keels. The thinnest lithospheric thickness is found under oceanic and continental rifts, as well as along convergence zones. We compare our results to thermal models of continental lithosphere, lithospheric cooling models of oceanic lithosphere, lithosphere-asthenosphere boundary (LAB) estimates from S-wave receiver functions, and velocity variations of global tomography models. In addition to comparing results for the broad region, we examine in detail the regions of Central Africa, Siberia, and Tibet. While there are clear differences in the various estimates, overall the results are generally consistent. Inconsistencies between the estimates may be due to a variety of reasons including lateral and depth resolution differences and the comparison of what may be different lithospheric features.
Energy Technology Data Exchange (ETDEWEB)
Kasten, P.R.; Coobs, J.H.; Lotts, A.L.
1976-04-01
Progress is summarized in studies relating to HTGR fuel reprocessing, refabrication, and recycle; HTGR fuel materials development and performance testing; HTGR PCRV development; HTGR materials investigations; HTGR fuel chemistry; HTGR safety studies; and GCFR irradiation experiments and steam generator modeling.
Structuring as a Basis for Product Modelling
DEFF Research Database (Denmark)
Mortensen, Niels Henrik; Hansen, Claus Thorp
1999-01-01
Structure means the way which things are built up. A composite product does not exhibit one structure, but hides in its structure of parts several different structuring principles, which fit the production, service, transport etc. Structuring of product models is complex where many factors...... are influencing. This paper identifies four factors that are influencing the structure of a product model: genetics, functionality/property, product life and product assortment. Three principles, which support determination of product model structures, are proposed....
Bury, S. J.; Zeldis, J. R.; Nodder, S. D.; Gall, M.
2012-01-01
We present the first field measured primary production values for an intermittently upwelling shelf ecosystem in the Hauraki Gulf, northeast New Zealand. Phytoplankton uptake rates of 13C and 15N were used to determine the relative importance of new (15NO3- ) versus regenerated nutrients (15NH4+ and 15N-urea) to productivity, and to test the hypothesis that the upwelling system supports high export of organic material, acting as a net sink for CO2. From early spring to early summer (1996-1997), deep NO3--rich waters upwelled onto the shelf and into the inner gulf, producing a short-lived low-level predominantly NO3--fuelled bloom (surface chlorophyll-a (chl-a) >1.0 mg m-3) in early spring. From late spring onwards, mixed layer NO3- concentrations were depleted to often lower levels than NH4+ and urea (∼0.1 mmol m-3), with mid-water chl-a maxima associated with the top of the nitracline fuelled predominantly by regenerated nutrients. By late summer, upwelling had ceased, with intrusions of low-nutrient subtropical oceanic surface water producing oligotrophic conditions. NH4+ and urea uptake nearly always exceeded NO3- uptake throughout the euphotic zone, even within the nitracline, with relative preference index (RPI) estimates giving RPIUrea>RPINH>RPINO, and low uptake f ratios (generally fphysiological preference of phytoplankton for reduced forms of nitrogen. Despite periods of upwelling producing relatively high levels of integrated NO3- (typically 25-150 mmol NO3- m-2) across the shelf from early spring to early summer, the highest integrated total production (1266 mg C m-2 d-1) and specific uptake rates of C/chl-a were obtained in late summer. In the inner gulf and on the mid-shelf, these higher late summer production rates coincided with low integrated chl-a biomass and NO3- inventories. There was no correlation of chl-a with C uptake in either surface waters (r2=0.0115), or in the euphotic zone (r2=0.0232) for the compiled data set, raising potential
Effect of Energy Intake during Dry Period on Production Performance of Postparturient Cows
Institute of Scientific and Technical Information of China (English)
LI Yan-fei; WANG Zhe; NIU Shu-ling
2004-01-01
24 healthy periparturient cows were randomly allocated into three groups and fed 100% energy diet (NRC standard diets), 120% energy diet and 80% energy diet, respectively, beginning at 28 days prior to anticipated parturition. After parturition, all the cows were provided with the lactation ration ad libitum until the day 56 postpartum.The objectives of the study were to investigate the effect of energy intake during the dry period on the production performance in the postpartum cows. The results indicated that the cows fed with high energy diet during the dry period had a lower dry material intake (DMI) and reduced milk production and a significant body weight (BW) loss compared with the cows fed with 80% energy diet and 100% energy diet, The results suggested that energy intake during the dry period was an important factor that influences and regulates DMI, milk production and energy equilibration of postparturient cows.
Impurity-induced antiferromagnetic domains in the periodic Anderson model
Benali, A.; Bai, Z. J.; Curro, N. J.; Scalettar, R. T.
2016-08-01
A central feature of the periodic Anderson model is the competition between antiferromagnetism, mediated by the Ruderman-Kittel-Kasuya-Yosida interaction at small conduction electron-local electron hybridization V , and singlet formation at large V . At zero temperature, and in dimension d >1 , these two phases are separated by a quantum critical point Vc. We use quantum Monte Carlo (QMC) simulations to explore the effect of impurities which have a local hybridization V*Vc . We measure the suppression of singlet correlations and the antiferromagnetic correlations which form around the impurity, as well as the size of the resulting domain. Exact diagonalization calculations for linear chains allow us to verify that the qualitative features obtained at intermediate coupling and finite T persist to strong coupling and T =0 , regimes which are difficult to access with QMC. Our calculations agree qualitatively with NMR measurements in CeCoIn5 -xCdx .
Exact solutions to plaquette Ising models with free and periodic boundaries
Directory of Open Access Journals (Sweden)
Marco Mueller
2017-01-01
We clarify the exact relation between partition functions with free and periodic boundary conditions expressed in terms of original and product spin variables for the 2d plaquette and 3d fuki-nuke models, noting that the differences are already present in the 1d Ising model. In addition, we solve the 2d plaquette Ising model with helical boundary conditions. The various exactly solved examples illustrate how correlations can be induced in finite systems as a consequence of the choice of boundary conditions.
Knegsel, van A.T.M.; Drift, van der S.G.A.; Cermáková, J.; Kemp, B.
2013-01-01
A dry period of 6–8 weeks for dairy cows is generally thought to maximise milk production in the next lactation. However, the value of such a long dry period is increasingly questioned. In particular, shortening the dry period shifts milk production from the critical period after calving to the
Knegsel, van A.T.M.; Drift, van der S.G.A.; Cermáková, J.; Kemp, B.
2013-01-01
A dry period of 6–8 weeks for dairy cows is generally thought to maximise milk production in the next lactation. However, the value of such a long dry period is increasingly questioned. In particular, shortening the dry period shifts milk production from the critical period after calving to the week
Production economic models of fisheries
DEFF Research Database (Denmark)
Andersen, J. L.
The overall purpose of this PhD thesis is to investigate different aspects of fishermen’s behaviour using production economic models at the individual and industry levels. Three parts make up this thesis. The first part provides an overview of the thesis. The second part consists of four papers...... analysing efficiency at the vessel level and factors influencing this. The third part consists of two papers and presents industry level analyses and focuses in particular on the likely impacts of implementing individual transferable quotas. The models are able to allow for changes in fishermen’s behaviour...... via individual learning and adjustments in output mix. All the papers included in Part II: Modelling and Evaluating Fishermen’s Behaviour consider factors influencing fishermen’s behaviour. Knowledge about these factors is important to give a correct description of fishermen’s behaviour. However...
The periodic competing Lotka-Volterra model with impulsive effect.
Liu, Bing; Chen, Lansun
2004-06-01
In this paper, the dynamic behaviour of a classical periodic Lotka-Volterra competing system with impulsive effect is investigated. By applying the Floquet theory of linear periodic impulsive equations, some conditions are obtained for the linear stability of the trivial and semi-trivial periodic solutions. It is proved that the system can be permanent if all the trivial and semi-trivial periodic solutions are linearly unstable. We use standard bifurcation theory to show the existence of nontrivial periodic solutions which arise near the semi-trivial periodic solution. As an application, a fish harvest problem is considered. We explain how two competing species, one of which in a periodic environment without impulsive effect would be doomed to extinction, can coexist with suitably periodic impulsive harvesting.
Alignment of Product Models and Product State Models - Integration of the Product Lifecycle Phases
DEFF Research Database (Denmark)
Larsen, Michael Holm; Kirkby, Lars Phillip; Vesterager, Johan
1999-01-01
The purpose of this paper is to discuss the integration of the Product Model (PM) and the Product State Model (PCM). Focus is on information exchange from the PSM to the PM within the manufacturing of a single ship. The paper distinguishes between information and knowledge integration. The paper...
Jenouvrier, Stéphanie; Caswell, Hal; Barbraud, Christophe; Weimerskirch, Henri
2010-06-01
We present a new approach to modeling two-sex populations, using periodic, nonlinear two-sex matrix models. The models project the population growth rate, the population structure, and any ratio of interest (e.g., operational sex ratio). The periodic formulation permits inclusion of highly seasonal behavioral events. A periodic product of the seasonal matrices describes annual population dynamics. The model is nonlinear because mating probability depends on the structure of the population. To study how the vital rates influence population growth rate, population structure, and operational sex ratio, we used sensitivity analysis of frequency-dependent nonlinear models. In nonlinear two-sex models the vital rates affect growth rate directly and also indirectly through effects on the population structure. The indirect effects can sometimes overwhelm the direct effects and are revealed only by nonlinear analysis. We find that the sensitivity of the population growth rate to female survival is negative for the emperor penguin, a species with highly seasonal breeding behavior. This result could not occur in linear models because changes in population structure have no effect on per capita reproduction. Our approach is applicable to ecological and evolutionary studies of any species in which males and females interact in a seasonal environment.
Production economic models of fisheries
DEFF Research Database (Denmark)
Andersen, Jesper Levring
The overall purpose of this PhD thesis is to investigate different aspects of fishermen’s behaviour using production economic models at the individual and industry levels. Three parts make up this thesis. The first part provides an overview of the thesis. The second part consists of four papers...... or fishing location. Behaviour can be viewed as being determined by the fishermen’s objectives subject to different restrictions, given by physical resources, time, mental capacity and information, and institutions. The review of the extensive literature gives reasonable support to the neoclassical...
Surface N Balances in Agricultural Crop production systems in China for the period 1980-2015
Sun, B.; Shen, R.P.; Bouwman, A.F.
2008-01-01
Surface nitrogen (N) balances for China's crop production systems were estimated using statistical data collected from 1980 to 2004 at the national and provincial scale and from 1994 to 1999 at the county level. There was a surplus N balance throughout these periods, but the surplus was nearly stabl
Ergot alkaloids in endophyte-infected grasses inhibit prolactin (PRL) secretion and may reduce milk production of cows consuming endophyte-infected grasses. We hypothesized that consumption of endophyte-infected fescue during the dry period inhibits mammary differentiation and subsequent milk produ...
The Behaviour of Gas Bubble during Rest Period of Pulse-Activated Electrolysis Hydrogen Production
Directory of Open Access Journals (Sweden)
Vilasmongkolchai Thanet
2016-01-01
Full Text Available The pulse-activated electrolyzer has been developed and used for several years. With the capability of enhancing the efficiency of an electrolytic process and easy operation, this technique becomes an interesting process for hydrogen production. Unfortunately during electrolytic reaction, the creation of bubbles becomes a reaction inhibitor and consumes energy. This paper aims to study the proper rest period that gives the bubble free rise-off the solution without additional bubble created. The mathematical method and acoustic emission method were used for investigation of bubble’s rising velocity. The result shows that the variation of rest period on pulse-activated makes production efficiency enhanced. For the practicality of use and set control parameters, duty cycle and frequency were demonstrated instead of rest period.
Characteristics of Period-Adding Bursting Bifurcation Without Chaos in the Chay Neuron Model
Institute of Scientific and Technical Information of China (English)
YANG Zhuo-Qin; LU Qi-Shao
2004-01-01
@@ A period-adding bursting sequence without bursting-chaos in the Chay neuron model is studied by bifurcation analysis. The genesis of each periodic bursting is separately evoked by the corresponding periodic spiking patterns through two period-doubling bifurcations, except for the period-1 bursting occurring via Hopf bifurcation. Hence,it is concluded that this period-adding bursting bifurcation without chaos has a compound bifurcation structure closely related to period-doubling bifurcations of periodic spiking in essence.
A calcium channel mutant mouse model of hypokalemic periodic paralysis.
Wu, Fenfen; Mi, Wentao; Hernández-Ochoa, Erick O; Burns, Dennis K; Fu, Yu; Gray, Hillery F; Struyk, Arie F; Schneider, Martin F; Cannon, Stephen C
2012-12-01
Hypokalemic periodic paralysis (HypoPP) is a familial skeletal muscle disorder that presents with recurrent episodes of severe weakness lasting hours to days associated with reduced serum potassium (K+). HypoPP is genetically heterogeneous, with missense mutations of a calcium channel (Ca(V)1.1) or a sodium channel (Na(V)1.4) accounting for 60% and 20% of cases, respectively. The mechanistic link between Ca(V)1.1 mutations and the ictal loss of muscle excitability during an attack of weakness in HypoPP is unknown. To address this question, we developed a mouse model for HypoPP with a targeted Ca(V)1.1 R528H mutation. The Ca(V)1.1 R528H mice had a HypoPP phenotype for which low K+ challenge produced a paradoxical depolarization of the resting potential, loss of muscle excitability, and weakness. A vacuolar myopathy with dilated transverse tubules and disruption of the triad junctions impaired Ca2+ release and likely contributed to the mild permanent weakness. Fibers from the Ca(V)1.1 R528H mouse had a small anomalous inward current at the resting potential, similar to our observations in the Na(V)1.4 R669H HypoPP mouse model. This "gating pore current" may be a common mechanism for paradoxical depolarization and susceptibility to HypoPP arising from missense mutations in the S4 voltage sensor of either calcium or sodium channels.
Refined Rotational Period, Pole Solution & Shape Model for (3200) Phaethon
Ansdell, Megan; Hainaut, Olivier; Buie, Marc W; Kaluna, Heather; Bauer, James; Dundon, Luke
2014-01-01
(3200) Phaethon exhibits both comet- and asteroid-like properties, suggesting it could be a rare transitional object such as a dormant comet or previously volatile-rich asteroid. This justifies detailed study of (3200) Phaethon's physical properties, as a better understanding of asteroid-comet transition objects can provide insight into minor body evolution. We therefore acquired time-series photometry of (3200) Phaethon over 15 nights from 1994 to 2013, primarily using the Tektronix 2048x2048 pixel CCD on the University of Hawaii 2.2-m telescope. We utilized light curve inversion to: (1) refine (3200) Phaethon's rotational period to P=3.6032+/-0.0008 h; (2) estimate a rotational pole orientation of lambda=+85+/-13 degrees and beta=-20+/-10 degrees; and (3) derive a shape model. We also used our extensive light curve dataset to estimate the slope parameter of (3200) Phaethon's phase curve as G~0.06, consistent with C-type asteroids. We discuss how this highly oblique pole orientation with a negative ecliptic ...
Product directivity models for parametric loudspeakers.
Shi, Chuang; Gan, Woon-Seng
2012-03-01
In a recent work, the beamsteering characteristics of parametric loudspeakers were validated in an experiment. It was shown that based on the product directivity model, the locations and amplitudes of the mainlobe and grating lobes could be predicted within acceptable errors. However, the measured amplitudes of sidelobes have not been able to match the theoretical results accurately. In this paper, the original theories behind the product directivity model are revisited, and three modified product directivity models are proposed: (i) the advanced product directivity model, (ii) the exponential product directivity model, and (iii) the combined product directivity model. The proposed product directivity models take the radii of equivalent Gaussian sources into account and obtain better predictions of sidelobes for the difference frequency waves. From the comparison between measurement results and numerical solutions, all the proposed models outperform the original product directivity model in terms of selected sidelobe predictions by about 10 dB.
Temporal diagnostic analysis of the SWAT model to detect dominant periods of poor model performance
Guse, Björn; Reusser, Dominik E.; Fohrer, Nicola
2013-04-01
Hydrological models generally include thresholds and non-linearities, such as snow-rain-temperature thresholds, non-linear reservoirs, infiltration thresholds and the like. When relating observed variables to modelling results, formal methods often calculate performance metrics over long periods, reporting model performance with only few numbers. Such approaches are not well suited to compare dominating processes between reality and model and to better understand when thresholds and non-linearities are driving model results. We present a combination of two temporally resolved model diagnostic tools to answer when a model is performing (not so) well and what the dominant processes are during these periods. We look at the temporal dynamics of parameter sensitivities and model performance to answer this question. For this, the eco-hydrological SWAT model is applied in the Treene lowland catchment in Northern Germany. As a first step, temporal dynamics of parameter sensitivities are analyzed using the Fourier Amplitude Sensitivity test (FAST). The sensitivities of the eight model parameters investigated show strong temporal variations. High sensitivities were detected for two groundwater (GW_DELAY, ALPHA_BF) and one evaporation parameters (ESCO) most of the time. The periods of high parameter sensitivity can be related to different phases of the hydrograph with dominances of the groundwater parameters in the recession phases and of ESCO in baseflow and resaturation periods. Surface runoff parameters show high parameter sensitivities in phases of a precipitation event in combination with high soil water contents. The dominant parameters give indication for the controlling processes during a given period for the hydrological catchment. The second step included the temporal analysis of model performance. For each time step, model performance was characterized with a "finger print" consisting of a large set of performance measures. These finger prints were clustered into
Methane production in an UASB reactor operated under periodic mesophilic-thermophilic conditions.
Bourque, J-S; Guiot, S R; Tartakovsky, B
2008-08-15
Methane production was studied in a laboratory-scale 10 L anaerobic upflow sludge bed (UASB) reactor with periodic variations of the reactor temperature. On a daily basis the temperature was varied between 35 and 45 degrees C or 35 and 55 degrees C with a heating period of 6 h. Each temperature increase was accompanied by an increase in methane production and a decrease in the concentration of soluble organic matter in the effluent. In comparison to a reactor operated at 35 degrees C, a net increase in methane production of up to 22% was observed. Batch activity tests demonstrated a tolerance of mesophilic methanogenic populations to short-term, 2-6 h, temperature increases, although activity of acetoclastic methanogens decreased after 6 h exposure to a temperature of 55 degrees C. 16S sequencing of DGGE bands revealed proliferation of temperature-tolerant Methanospirillum hungatii sp. in the reactor.
A comparison of Maize Production in Kenya before and during Liberalisation Period
Directory of Open Access Journals (Sweden)
Mbithi, LM.
2000-01-01
Full Text Available Maize is the main food crop grown in Kenya. It is planted on 90 % of ail Kenyan farms and together with ifs commonly intercropped crop, beans, occupies over 22 % of all farmed land. In addition to being the staple food, maize production is also a source of capital and employment to a majority of the rural people. Total maize production, yield, area planted and average an-nual rainfall before and after market liberalisation is compared. Statistical analysis showed that both yield and total maize production increased significantly after the input and output market liberalisation while area planted with maize and average annual rainfall did not change significantly. Both yield and total production of maize show less variability in the liberalised period than before. These observations led to the conclusion that input and output market liberalisation policies could have led to increased yields and therefore increased total production of maize in general in Kenya.
A grand model for chemical product design
DEFF Research Database (Denmark)
Fung, Ka Y.; Ng, Ka M.; Zhang, Lei;
2016-01-01
Chemical engineering has been expanding its focus from primarily business-to-business products (B2B) to business-to-consumer (B2C) products. The production of B2B products generally emphasizes on process design and optimization, whereas the production of B2C products focuses on product quality......, ingredients and structure. Market and competitive analysis, government policies and regulations have to be explicitly considered in product design. All these considerations are accounted for in the Grand Product Design Model, which consists of a process model, a property model, a quality model, a cost model...... product composition changes with market conditions. Another is a hand lotion that illustrates how product quality affects the profit.(C) 2016 Elsevier Ltd. All rights reserved....
Extending product modeling methods for integrated product development
DEFF Research Database (Denmark)
Bonev, Martin; Wörösch, Michael; Hauksdóttir, Dagný
2013-01-01
Despite great efforts within the modeling domain, the majority of methods often address the uncommon design situation of an original product development. However, studies illustrate that development tasks are predominantly related to redesigning, improving, and extending already existing products....... Updated design requirements have then to be made explicit and mapped against the existing product architecture. In this paper, existing methods are adapted and extended through linking updated requirements to suitable product models. By combining several established modeling techniques, such as the DSM...... and PVM methods, in a presented Product Requirement Development model some of the individual drawbacks of each method could be overcome. Based on the UML standard, the model enables the representation of complex hierarchical relationships in a generic product model. At the same time it uses matrix...
Koprivica, Slavica; Siller, Martin; Hosoya, Takashi; Roggenstein, Walter; Rosenau, Thomas; Potthast, Antje
2016-04-21
A method for easy and fast regeneration of aqueous periodate solutions from dialdehyde cellulose (DAC) production by ozone treatment is presented, along with a direct and reliable simultaneous quantification of iodate and periodate by reversed-phase HPLC. The influence of iodate and ozone concentration, solution pH, and reaction time on the regeneration efficiency was studied, as well as the reaction kinetics. Regeneration of spent periodate solutions by ozone was successfully performed in alkaline medium, which favors the formation of free (.) OH radicals, as supported by the addition of radical scavengers and quantum mechanical calculations. At pH 13 and an ozone concentration of approximately 150 mg L(-1) , periodate was completely regenerated from a 100 mm solution of iodate within 1 h at room temperature. A cyclic process of cellulose oxidation and subsequent regeneration of spent periodate with 90 % efficiency has been developed. So far, commercial applications of DAC have been hampered by difficulties in reusing the costly periodate. This work overcomes this hurdle and presents a highly efficient, clean, and low-cost protocol for the preparation of DAC with integrated periodate recycling, with the possibility of scaling the process up.
Directory of Open Access Journals (Sweden)
Po-Yu Chen
2014-01-01
Full Text Available The validness of the expiration dates (validity period that manufacturers provide on food product labels is a crucial food safety problem. Governments must study how to use their authority by implementing fair awards and punishments to prompt manufacturers into adopting rigorous considerations, such as the effect of adopting new storage methods for extending product validity periods on expected costs. Assuming that a manufacturer sells fresh food or drugs, this manufacturer must respond to current stochastic demands at each unit of time to determine the purchase amount of products for sale. If this decision maker is capable and an opportunity arises, new packaging methods (e.g., aluminum foil packaging, vacuum packaging, high-temperature sterilization after glass packaging, or packaging with various degrees of dryness or storage methods (i.e., adding desiccants or various antioxidants can be chosen to extend the validity periods of products. To minimize expected costs, this decision maker must be aware of the processing costs of new storage methods, inventory standards, inventory cycle lengths, and changes in relationships between factors such as stochastic demand functions in a cycle. Based on these changes in relationships, this study established a mathematical model as a basis for discussing the aforementioned topics.
Holding Period Return-Risk Modeling: Ambiguity in Estimation
W.G.P.M. Hallerbach (Winfried)
2003-01-01
textabstractIn this paper we explore the theoretical and empirical problems of estimating average (excess) return and risk of US equities over various holding periods and sample periods. Our findings are relevant for performance evaluation, for estimating the historical equity risk premium, and for
Holding Period Return-Risk Modeling: Ambiguity in Estimation
W.G.P.M. Hallerbach (Winfried)
2003-01-01
textabstractIn this paper we explore the theoretical and empirical problems of estimating average (excess) return and risk of US equities over various holding periods and sample periods. Our findings are relevant for performance evaluation, for estimating the historical equity risk premium, and for
A Novel Method for Optimal Solution of Fuzzy Chance Constraint Single-Period Inventory Model
Directory of Open Access Journals (Sweden)
Anuradha Sahoo
2016-01-01
Full Text Available A method is proposed for solving single-period inventory fuzzy probabilistic model (SPIFPM with fuzzy demand and fuzzy storage space under a chance constraint. Our objective is to maximize the total profit for both overstock and understock situations, where the demand D~j for each product j in the objective function is considered as a fuzzy random variable (FRV and with the available storage space area W~, which is also a FRV under normal distribution and exponential distribution. Initially we used the weighted sum method to consider both overstock and understock situations. Then the fuzziness of the model is removed by ranking function method and the randomness of the model is removed by chance constrained programming problem, which is a deterministic nonlinear programming problem (NLPP model. Finally this NLPP is solved by using LINGO software. To validate and to demonstrate the results of the proposed model, numerical examples are given.
Modelling of virtual production networks
Directory of Open Access Journals (Sweden)
2011-03-01
Full Text Available Nowadays many companies, especially small and medium-sized enterprises (SMEs, specialize in a limited field of production. It requires forming virtual production networks of cooperating enterprises to manufacture better, faster and cheaper. Apart from that, some production orders cannot be realized, because there is not a company of sufficient production potential. In this case the virtual production networks of cooperating companies can realize these production orders. These networks have larger production capacity and many different resources. Therefore it can realize many more production orders together than each of them separately. Such organization allows for executing high quality product. The maintenance costs of production capacity and used resources are not so high. In this paper a methodology of rapid prototyping of virtual production networks is proposed. It allows to execute production orders on time considered existing logistic constraints.
Daryaei, A; Jones, E E; Ghazalibiglar, H; Glare, T R; Falloon, R E
2016-04-01
The goal was to determine the effect of temperature, light and incubation period on production, germination and bioactivity of Trichoderma atroviride LU132 against Rhizoctonia solani. The incubation temperatures of 20, 25 or 30°C were assessed on the production of T. atroviride conidia under constant light over a 25 and 50 days periods. The resulting conidia were also studied for germination and bioactivity. Conidium production was maximum at 25°C after 20 days. The second peak of conidium production occurred at 45-50 days. Incubation at 25°C after 15 days showed optimum production of T. atroviride LU132. Conidia produced at 30°C gave the greatest germination and bioactivity in comparison with incubation at 20 or 25°C. This study indicates that the temperature at which conidia of T. atroviride are produced affects germination and bioactivity. Formulations based on production of the high conidia yield may not result in optimal bioactivity and there is a trade-off between quantity and quality of T. atroviride LU132 conidia. Conidium production was shown to be a continuous process, and increased under a dark/light regime. This is the first report of bimodal conidium production in a Trichoderma biological control agent (BCA), which is likely to be on 20 days cycle, and is dependent on colony age rather than abiotic factors. Conidia produced after 15 days are likely to be the most suitable for use in commercial production of this strain as a BCA. Most studies on Trichoderma-based BCA have only shown the effect of culture conditions on the high conidia yield regardless of conidium quality. This study is the first report on conidium quality affected by principal culture conditions for Trichoderma biological control formulations. © 2016 The Society for Applied Microbiology.
A procedure for Building Product Models
DEFF Research Database (Denmark)
Hvam, Lars
1999-01-01
, easily adaptable concepts and methods from data modeling (object oriented analysis) and domain modeling (product modeling). The concepts are general and can be used for modeling all types of specifications in the different phases in the product life cycle. The modeling techniques presented have been...
The economic production lot size model with several production rates
DEFF Research Database (Denmark)
Larsen, Christian
should be chosen in the interval between the demand rate and the production rate, which minimize unit production costs, and should be used in an increasing order. Then, given the production rates, we derive closed form solutions for the optimal runtimes as well as the minimum average cost. Finally we......We study an extension of the economic production lot size model, where more than one production rate can be used during a cycle. The production rates and their corresponding runtimes are decision variables. We decompose the problem into two subproblems. First, we show that all production rates...
Product model structure for generalized optimal design
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The framework of the generalized optimization product model with the core of network- and tree-hierarchical structure is advanced to improve the characteristics of the generalized optimal design. Based on the proposed node-repetition technique, a network-hierarchical structure is united with the tree-hierarchical structure to facilitate the modeling of serialization and combination products. The criteria for product decomposition are investigated. Seven tree nodes are defined for the construction of a general product model, and their modeling properties are studied in detail. The developed product modeling system is applied and examined successfully in the modeling practice of the generalized optimal design for a hydraulic excavator.
Modelling the trade off between period lenght and stages in a period batch control system
Riezebos, J.
1997-01-01
The purpose of this paper is to propose a nonparametric interest rate term structure model and investigate its implications on term structure dynamics and prices of interest rate derivative securities. The nonparametric spot interest rate process is estimated from the observed short-term interest
Modelling the trade off between period lenght and stages in a period batch control system
Riezebos, J.
1997-01-01
The purpose of this paper is to propose a nonparametric interest rate term structure model and investigate its implications on term structure dynamics and prices of interest rate derivative securities. The nonparametric spot interest rate process is estimated from the observed short-term interest ra
Continuous matrix product states with periodic boundary conditions and an application to atomtronics
Draxler, Damian; Haegeman, Jutho; Verstraete, Frank; Rizzi, Matteo
2017-01-01
We introduce a time evolution algorithm for one-dimensional quantum field theories with periodic boundary conditions. This is done by applying the Dirac-Frenkel time-dependent variational principle to the set of translational invariant continuous matrix product states with periodic boundary conditions. Moreover, the ansatz is accompanied with additional boundary degrees of freedom to study quantum impurity problems. The algorithm allows for a cutoff in the spectrum of the transfer matrix and thus has an efficient computational scaling. In particular we study the prototypical example of an atomtronic system—an interacting Bose gas rotating in a ring shaped trap in the presence of a localized barrier potential.
Testing eccentricity pumping mechanisms to model eccentric long period sdB binaries with MESA
Vos, Joris; Marchant, Pablo; Van Winckel, Hans
2015-01-01
Hot subdwarf-B stars in long-period binaries are found to be on eccentric orbits, even though current binary-evolution theory predicts those objects to be circularised before the onset of Roche-lobe overflow (RLOF). We aim to find binary-evolution mechanisms that can explain these eccentric long-period orbits, and reproduce the currently observed period-eccentricity diagram. Three different processes are considered; tidally-enhanced wind mass-loss, phase-dependent RLOF on eccentric orbits and the interaction between a circumbinary disk and the binary. The binary module of the stellar-evolution code MESA (Modules for Experiments in Stellar Astrophysics) is extended to include the eccentricity-pumping processes. The effects of different input parameters on the final period and eccentricity of a binary-evolution model are tested with MESA. The end products of models with only tidally-enhanced wind mass-loss can indeed be eccentric, but these models need to lose too much mass, and invariably end up with a helium ...
Product Customization in the Spokes Model
Aoki, Reiko; Hillas, John; Kao, Tina
2014-01-01
We use a spokes model to analyze ?ms?customization incentives when facing the choices of standard and niche products. Products at or near the end of the spokes are customized products, while products near the origin are more standardized products that cater to the taste of many consumers. Our results indicate that although monopolist always offers the standard product, if a ?m anticipates entry, it may choose to stake claim to a customized product. For low transportation costs, the early entr...
EVALUATION OF PRODUCTION IN SEASONALITY PERIODS: ANALYSIS OF THE CONSTRUCTION INDUSTRY IN BRAZIL
Directory of Open Access Journals (Sweden)
Marcos William Kaspchak Machado
2013-06-01
Full Text Available The present work has as an objective to evaluate the impacts of production seasonality in seasonality periods in the Brazilian construction industry. The adopted methodology was based on the qualitative and quantitative approaches of the aspects inherent to the seasonality factors in the construction industry and its possible causes. Besides that, literature data were collected in year report books and devices provided by institutions of the sector. The results demonstrated the importance of production management mechanisms to optimize the use of productive factors through cost analysis, which are fundamental to understand the operational flux of resources used in the operational media. Obtaining this information, connected to market indicators helped in the decision making process related to the development of prospective scenarios which will give support to the decision making strategy aiming to stabilize the production levels.
Attitudes of Turkish Consumers toward Foreign Products in Political Crises Period
Directory of Open Access Journals (Sweden)
Durmus YÖRÜK
2016-04-01
Full Text Available This study aims to understand the attitudes of Turkish consumers toward foreign products in diplomatic crisis period. With this aim, at first, demographic characteristics of the consumers identified and then the relationship between independent variables which are consumer ethnocentrism and consumer animosity, and dependent variable which is willingness to buy foreign products is determined. In addition, the effect of product judgment as a moderator on the relationship between willingness to buy foreign products and consumer ethnocentrism and animosity is explored. Convenience sampling method was used in the study. Data was collected from students in Faculty of Economics and Administrative Sciences of Afyon Kocatepe University as based on voluntary basis. The data were collected between 20.10.2015 and 02.11.2015 and within this time period, it was reached to 418 students, totally. Thus, these 418 students in Faculty of Economics and Administrative Sciences became the sample of the research. Research findings show, different from the many researches in the literature, that consumer ethnocentrism, and consumer animosity do not negatively affect the willingness to buy foreign products even in a case when Turkey has a diplomatic problem with some countries. So the previous findings about the consumer ethnocentrism and the consumer animosity are challenged with the findings of this study within Turkey context. In this sense, this study contributes to the literature scholarly, by offering new findings about the existing constructs within different country context.
Evaluation of raw milk quality in different production systems and periods of the year
Directory of Open Access Journals (Sweden)
Marcos Inácio Marcondes
2014-12-01
Full Text Available The objective of this study was to evaluate the quality of raw milk in different production systems and its variation throughout the year. The data were collected from 943 dairy farms in the South, Central-West and Central regions of the state of Minas Gerais, and in Vale do Paraíba, in the state of São Paulo, Brazil. The data were collected in the period from January 2009 to September 2011, in a total of 18,206 samples. The properties were divided into confinement, semi-confinement and extensive production systems. The evaluated factors were somatic cell count (SCC, total bacterial count (TBC and protein and fat contents. There was no effect of production system on the contents of protein, fat and SCC. Total bacterial count, however, was affected by production. Seasonal variations were found for SCC, TBC, protein and fat; the highest protein values were found from March to June; the highest fat contents were obtained from May to August; and TBC and SCC, from December to March. The production system does not interfere with the percentage of fat and protein and SCC of the milk. However, confinement systems present a better TBC content. Both month and year are factors that interfere with TBC, SCC, protein and milk fat, and the best patterns are found in the coldest periods of the year.
A calcium channel mutant mouse model of hypokalemic periodic paralysis
National Research Council Canada - National Science Library
Wu, Fenfen; Mi, Wentao; Hernández-Ochoa, Erick O; Burns, Dennis K; Fu, Yu; Gray, Hillery F; Struyk, Arie F; Schneider, Martin F; Cannon, Stephen C
2012-01-01
Hypokalemic periodic paralysis (HypoPP) is a familial skeletal muscle disorder that presents with recurrent episodes of severe weakness lasting hours to days associated with reduced serum potassium (K+...
Age-period-cohort models using smoothing splines: a generalized additive model approach.
Jiang, Bei; Carriere, Keumhee C
2014-02-20
Age-period-cohort (APC) models are used to analyze temporal trends in disease or mortality rates, dealing with linear dependency among associated effects of age, period, and cohort. However, the nature of sparseness in such data has severely limited the use of APC models. To deal with these practical limitations and issues, we advocate cubic smoothing splines. We show that the methods of estimable functions proposed in the framework of generalized linear models can still be considered to solve the non-identifiability problem when the model fitting is within the framework of generalized additive models with cubic smoothing splines. Through simulation studies, we evaluate the performance of the cubic smoothing splines in terms of the mean squared errors of estimable functions. Our results support the use of cubic smoothing splines for APC modeling with sparse but unaggregated data from a Lexis diagram.
Field, Richard J.; Gallas, Jason A. C.; Schuldberg, David
2017-08-01
Recent work has introduced social dynamic models of people's stress-related processes, some including amelioration of stress symptoms by support from others. The effects of support may be ;direct;, depending only on the level of support, or ;buffering;, depending on the product of the level of support and level of stress. We focus here on the nonlinear buffering term and use a model involving three variables (and 12 control parameters), including stress as perceived by the individual, physical and psychological symptoms, and currently active social support. This model is quantified by a set of three nonlinear differential equations governing its stationary-state stability, temporal evolution (sometimes oscillatory), and how each variable affects the others. Chaos may appear with periodic forcing of an environmental stress parameter. Here we explore this model carefully as the strength and amplitude of this forcing, and an important psychological parameter relating to self-kindling in the stress response, are varied. Three significant observations are made: 1. There exist many complex but orderly regions of periodicity and chaos, 2. there are nested regions of increasing number of peaks per cycle that may cascade to chaos, and 3. there are areas where more than one state, e.g., a period-2 oscillation and chaos, coexist for the same parameters; which one is reached depends on initial conditions.
Energy Technology Data Exchange (ETDEWEB)
King, L.J.; Bigelow, J.E.; Collins, E.D.
1976-10-01
Between July 1, 1975, and December 31, 1975, maintenance was conducted at TRU for a period of three months, 295 g of curium oxide (enough for approximately 26 HFIR targets) were prepared, 100 mg of high-purity /sup 248/Cm, were separated from /sup 252/Cf that had been purified during earlier periods, 11 HFIR targets were fabricated, and 28 product shipments were made. No changes were made in the chemical processing flowsheets normally used at TRU during this report period. However, three equipment racks were replaced (with two new racks) during this time. In Cubicle 6, the equipment replaced was that used to decontaminate the transplutonium elements from rare earth fission products and to separate curium from the heavier elements by means of the LiCl-based anion-exchange process. In Cubicle 5, the equipment used to separate the transcurium elements by high-pressure ion exchange and to purify berkelium by batch solvent extraction was replaced. Two neutron sources were fabricated, bringing the total fabricated to 79. One source that had been used in a completed project was returned to the TRU inventory and is available for reissue. Three sources, for which no further use was foreseen, were processed to isolate and recover the ingrown /sup 248/Cm and the residual /sup 252/Cf. Eight pellets, each containing 100 ..mu..g of high-purity /sup 248/Cm were prepared for irradiation in HFIR to study the production of /sup 250/Cm. The values currently being used for transuranium element decay data and for cross-section data in planning irradiation-processing cycles, calculating production forecasts, and assaying products are tabulated.
The effect of dry period length on productive, reproductive and health parameters of dairy cows
Directory of Open Access Journals (Sweden)
Ryszard Skrzypek
2016-03-01
Full Text Available The purpose of this study was the analysis of effects of dry period length on milk performance, fertility and health of Polish Holstein-Friesian cows. The analysis was carried out on data from 426 cows, managed on a free-stall farm. All animals were dried off under the protection of antibiotics that were applied into mammary gland after the last milking. Cows with the shortest dry period (≤ 42 days produced least milk with the highest protein content and the highest somatic cell count, they also had most favourable reproduction parameters The middle-length dry period (43–70 days was associated with the highest milk production, and the longest period (> 70 days was associated with the lowest somatic cell count and the least favourable reproduction parameters. Results of this study show that there is no optimal universal length of dry period, and therefore in practical dairy farming it should be matched if possible to particular groups or even individual animals.
Solar Output Controls Periodicity in Lake Productivity and Wetness at Southernmost South America
Pérez-Rodríguez, Marta; Gilfedder, Benjamin-Silas; Hermanns, Yvonne-Marie; Biester, Harald
2016-11-01
Cyclic changes in total solar irradiance (TSI) during the Holocene are known to affect global climatic conditions and cause cyclic climatic oscillations, e.g., Bond events and related changes of environmental conditions. However, the processes how changes in TSI affect climate and environment of the Southern Hemisphere, especially in southernmost South America, a key area for the global climate, are still poorly resolved. Here we show that highly sensitive proxies for aquatic productivity derived from sediments of a lake near the Chilean South Atlantic coast (53 °S) strongly match the cyclic changes in TSI throughout the Holocene. Intra-lake productivity variations show a periodicity of ~200-240 years coherent with the time series of TSI-controlled cosmogenic nuclide 10Be production. In addition TSI dependent periodicity of Bond events (~1500 years) appear to control wetness at the LH site indicated by mineral matter erosion from the catchment to the lake assumingly through shifts of the position of the southern westerly wind belt. Thus, both intra-lake productivity and wetness at the southernmost South America are directly or indirectly controlled by TSI.
Shargel, Benjamin Hertz; Chou, Tom
2009-10-01
Asymptotic fluctuation theorems are statements of a Gallavotti-Cohen symmetry in the rate function of either the time-averaged entropy production or heat dissipation of a process. Such theorems have been proved for various general classes of continuous-time deterministic and stochastic processes, but always under the assumption that the forces driving the system are time independent, and often relying on the existence of a limiting ergodic distribution. In this paper we extend the asymptotic fluctuation theorem for the first time to inhomogeneous continuous-time processes without a stationary distribution, considering specifically a finite state Markov chain driven by periodic transition rates. We find that for both entropy production and heat dissipation, the usual Gallavotti-Cohen symmetry of the rate function is generalized to an analogous relation between the rate functions of the original process and its corresponding backward process, in which the trajectory and the driving protocol have been time-reversed. The effect is that spontaneous positive fluctuations in the long time average of each quantity in the forward process are exponentially more likely than spontaneous negative fluctuations in the backward process, and vice-versa, revealing that the distributions of fluctuations in universes in which time moves forward and backward are related. As an additional result, the asymptotic time-averaged entropy production is obtained as the integral of a periodic entropy production rate that generalizes the constant rate pertaining to homogeneous dynamics.
Kanban simulation model for production process optimization
Directory of Open Access Journals (Sweden)
Golchev Riste
2015-01-01
Full Text Available A long time has passed since the KANBAN system has been established as an efficient method for coping with the excessive inventory. Still, the possibilities for its improvement through its integration with other different approaches should be investigated further. The basic research challenge of this paper is to present benefits of KANBAN implementation supported with Discrete Event Simulation (DES. In that direction, at the beginning, the basics of KANBAN system are presented with emphasis on the information and material flow, together with a methodology for implementation of KANBAN system. Certain analysis on combining the simulation with this methodology is presented. The paper is concluded with a practical example which shows that through understanding the philosophy of the implementation methodology of KANBAN system and the simulation methodology, a simulation model can be created which can serve as a basis for a variety of experiments that can be conducted within a short period of time, resulting with production process optimization.
Shanghai's Administrative Model for Private Schools during the Republican Period
Shi, Kouzhu
2008-01-01
Private schools were very prosperous in Shanghai during the Republican period. Shanghai Municipal Educational Bureau adopted a pattern of indirect management, especially attaching importance to normalizing and guiding the mechanism for operating a school by taking the basic measures for the registration administration. Meanwhile, appropriate…
The location model with two periods of price competition
Webers, H.M.
1994-01-01
In this paper we characterize the subgame perfect Nash equilibria of a location-then-price game where firms first choose locations and after that compete for prices in two subsequent periods. Locations are thus seen as long term commitments. There are two types of consumers, each with different valu
Skill assessment of the PELAGOS global ocean biogeochemistry model over the period 1980–2000
Directory of Open Access Journals (Sweden)
M. Vichi
2009-04-01
of primary and bacterial production at BATS. These results have been further strenghtened with an analysis of spatial variability of microbial carbon production/consumption and comparison with observations along a transect in the Atlantic ocean. Within the limits of the model assumption and known biases, PELAGOS predicts that the system is net heterotrophic if the boreal winter period only is considered and especially in the more oligotrophic regions. However, at the annual time scale and over the global ocean, the model suggests that surface ocean is close to a slightly positive autotrophic balance in accordance with recent experimental findings and geochemical evidences.
A procedure for building product models
DEFF Research Database (Denmark)
Hvam, Lars; Riis, Jesper; Malis, Martin
2001-01-01
with product models. The next phase includes an analysis of the product assortment, and the set up of a so-called product master. Finally the product model is designed and implemented using object oriented modelling. The procedure is developed in order to ensure that the product models constructed are fit...... for the business processes they support, and properly structured and documented, in order to facilitate that the systems can be maintained continually and further developed. The research has been carried out at the Centre for Industrialisation of Engineering, Department of Manufacturing Engineering, Technical...
An Optimization Model for Product Placement on Product Listing Pages
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Yan-Kwang Chen
2014-01-01
Full Text Available The design of product listing pages is a key component of Website design because it has significant influence on the sales volume on a Website. This study focuses on product placement in designing product listing pages. Product placement concerns how venders of online stores place their products over the product listing pages for maximization of profit. This problem is very similar to the offline shelf management problem. Since product information sources on a Web page are typically communicated through the text and image, visual stimuli such as color, shape, size, and spatial arrangement often have an effect on the visual attention of online shoppers and, in turn, influence their eventual purchase decisions. In view of the above, this study synthesizes the visual attention literature and theory of shelf-space allocation to develop a mathematical programming model with genetic algorithms for finding optimal solutions to the focused issue. The validity of the model is illustrated with example problems.
Proactive Modeling of Market, Product and Production Architectures
DEFF Research Database (Denmark)
Mortensen, Niels Henrik; Hansen, Christian Lindschou; Hvam, Lars;
2011-01-01
This paper presents an operational model that allows description of market, products and production architectures. The main feature of this model is the ability to describe both structural and functional aspect of architectures. The structural aspect is an answer to the question: What constitutes...... the architecture, e.g. standard designs, design units and interfaces? The functional aspect is an answer to the question: What is the behaviour or the architecture, what is it able to do, i.e. which products at which performance levels can be derived from the architecture? Among the most important benefits...... of this model is the explicit ability to describe what the architecture is prepared for, and what it is not prepared for - concerning development of future derivative products. The model has been applied in a large scale global product development project. Among the most important benefits is contribution to...
The Single Period Inventory Model: Origins, Solutions, Variations, and Applications.
1977-09-01
34News boy problem ", [1] "Newspaper boy problem ", [2] "Newspaper vendor problem ", [3] " Newsvendor problem ", [4] "Christmas tree problem ", [5] and so...miXr) % ^The classic newspaper boy or single period inventory problem is reviewed, and its origins and development during the past 30 years are...traced. The review reveals several variations for the classic problem , both in cost structure and in the decision principles involved. The critical
Architecture of the Product State Model Environment
DEFF Research Database (Denmark)
Holm Larsen, Michael; Lynggaard, Hans Jørgen B.
2003-01-01
This paper addresses the issue of using product models to support product lifecycle activities withparticular focus on the production phase. The motivation of the research is that products are producedmore costly and with longer lead-time than necessary.The paper provides a review of product...... modelling technologies and approaches, and the overallarchitecture for the Product State Model (PSM) Environment as a basis for quality monitoring.Especially, the paper focuses on the circumstances prevailing in a one-of-a-kind manufacturingenvironment like the shipbuilding industry, where product modelling...... technologies already haveproved their worth in the design and engineering phases of shipbuilding and in the operation phase.However, the handling of product information on the shop floor is not yet equally developed.The paper reports from the Brite-Euram project (No. BE97-4510) QualiGlobe focusing...
MASS CUSTOMIZATION and PRODUCT MODELS
DEFF Research Database (Denmark)
Svensson, Carsten; Malis, Martin
2003-01-01
to the product. Through the application of a mass customization strategy, companies have a unique opportunity to create increased customer satisfaction. In a customized production, knowledge and information have to be easily accessible since every product is a unique combination of information. If the dream...... of a customized alternative instead of a uniform mass-produced product shall become a reality, then the cross-organizational efficiency must be kept at a competitive level. This is the real challenge for mass customization. A radical restructuring of both the internal and the external knowledge management systems...
Product Family Modelling for Manufacturing Planning
DEFF Research Database (Denmark)
Jørgensen, Kaj Asbjørn; Petersen, Thomas Ditlev; Nielsen, Kjeld
2011-01-01
of the product family model, however, the model should be enriched with data for planning and execution of the manufacturing processes. The idea is that, when any individual product is specified using the product configurator, a product model can be extracted with all data necessary for planning...... of the manufacturing processes. Obviously, data for identification of all used modules and components are included in the product model but also for instance data for processing and assembly operations must be available. These data are not always related entirely to the modules and components but are sometimes also...... dependent on the specific assembly structure of the configured product, i.e. the combination of modules. In this paper, issues of how to create manufacturing structures and related planning data in product family models are presented. Primarily, the more complicated multi-level manufacturing structures...
A Moebius-Strip Representation of the Matrix-Product Periodic System of Diatomic Molecules
Hefferlin, Ray
2007-04-01
Periodic systems of diatomic and triatomic molecules are well tested and documented [1]. The 3D form of the diatomic system consists of blocks, each having all molecules with two fixed-row atoms, on which the molecules are addressed by their atomic group numbers. The blocks can be replaced by tori [2], but in either case many redundancies exist (e.g., CO and OC). The tori [3] may be replaced by Moebius strips [4] which remove the redundancies. This representation of the periodic system will be presented. [1] Hefferlin, R., ``The Periodic Systems of Molecules, Presuppositions, Problems, and Prospects,'' Baird, D., Scerri, E., and McIntyre, L., Editors, Philosophy of Chemistry, Boston Studies in the Philosophy of Science, Springer, Dodrecht, the Netherlands, 2006. [2] Hefferlin, R,. ``Matrix-Product Periodic Systems of Molecules,'' J. Chem. Inf. Comput. Sci, 34, 314-317 (1994). [3] Hall, D. E, ``Quantitative Evaluation of Musical Scale Tunings,'' AJP, 42, 543-552 (1974). [4] Blau, S. K., ``Good Music unfolds in Small Steps,'' Physics Today, October 2006, pp. 19-21.
CRC-cards for Product Modelling
DEFF Research Database (Denmark)
Hvam, Lars; Riis, Jesper; Hansen, Benjamin Loer
2003-01-01
, transportation, service and decommissioning. A main challenge when building product models is to collect and document the product related data, information and knowledge in a structured way. CRC cards are index cards (or computerized versions of these) which are used to record proposed classes, the behavior......This paper describes the CRC (class, responsibility, collaboration) modelling process for building product models. A product model is normally represented in an IT system which contains data, information and knowledge on industrial products and their life cycle properties e.g. manufacturing...... of the classes, their responsibilities, and their relationship to other classes (collaboration). CRC modelling gives an effective, low-tech method for domain-experts, programmers and users to work closely together to identify, structure, understand and document a product model. CRC cards were originally...
Periodicity and chaos on a modified Samuelson model
2003-01-01
Several discrete time nonlinear growth models with complicated dynamical behavior have been introduced in the literature. In this paper we propuse a modified Samuelson model and we study its dynamical behavior depending on several parameters, which turn out to be the same as the logistic family. Moreover in the base situation the dynamical behavior only depends on the initial values of supply and demand.
Proactive Modeling of Market, Product and Production Architectures
DEFF Research Database (Denmark)
Mortensen, Niels Henrik; Hansen, Christian Lindschou; Hvam, Lars
2011-01-01
This paper presents an operational model that allows description of market, products and production architectures. The main feature of this model is the ability to describe both structural and functional aspect of architectures. The structural aspect is an answer to the question: What constitutes...... the architecture, e.g. standard designs, design units and interfaces? The functional aspect is an answer to the question: What is the behaviour or the architecture, what is it able to do, i.e. which products at which performance levels can be derived from the architecture? Among the most important benefits......: Improved preparedness for future launches, e.g. user interface and improved energy efficiency Achievement of attractive cost- and technical performance level on all products in the product family On time launch of the first generation of the product family"...
Smith, G L; Friggens, N C; Ashworth, C J; Chagunda, M G G
2017-02-15
. Cows diagnosed with subclinical mastitis in the first 30 days of lactation had significantly greater milk yield at dry off in the previous lactation than cows that developed a reproductive tract disorder or metabolic disease in addition to a significantly higher yield to body energy content ratio at dry off than healthy cows. Physiological and production traits recorded in the lactation and dry period preceding a disease event differed between cows which developed different diseases post-calving. Differences in these traits allow the development of new disease indicators for use in models for the prediction of disease risk in the transition period.
Modeling of Kefir Production with Fuzzy Logic
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Hüseyin Nail Akgül
2014-06-01
Full Text Available The fermentation is ended with pH 4.6 values in industrial production of kefir. In this study, the incubation temperature, the incubation time and inoculums of culture were chose as variable parameters of kefir. In conventional control systems, the value of pH can be found by trial method. In these systems, if the number of input parameters is greater, the method of trial and error creates a system dependent on the person as well as troublesome. Fuzzy logic can be used in such cases. Modeling studies with this fuzzy logic control are examined in two portions. The first part consists of fuzzy rules and membership functions, while the second part consists of clarify. Kefir incubation temperature between 20 and 25°C, the incubation period between 18 to 22 hours and the inoculum ratio of culture between 1-5% are selected for optimum production conditions. Three separate fuzzy sets (triangular membership function are used to blur the incubation temperature, the incubation time and the inoculum ratio of culture. Because the membership function numbers belonging to the the input parameters are 3 units, 3x3x3=27 line rule is obtained by multiplying these numbers. The table of fuzzy rules was obtained using the method of Mamdani. The membership function values were determined by the method of average weight using three trapezoidal area of membership functions created for clarification. The success of the system will be found, comparing the numerical values obtained with pH values that should be. Eventually, to achieve the desired pH value of 4.6 in the production of kefir, with the using of fuzzy logic, the workload of people will be decreased and the productivity of business can be increased. In this case, it can be provided savings in both cost and time.
A calcium channel mutant mouse model of hypokalemic periodic paralysis
Wu, Fenfen; Mi, Wentao; Hernández-Ochoa, Erick O.; Burns, Dennis K.; Fu, Yu; Gray, Hillery F; Struyk, Arie F.; Martin F Schneider; Cannon, Stephen C.
2012-01-01
Hypokalemic periodic paralysis (HypoPP) is a familial skeletal muscle disorder that presents with recurrent episodes of severe weakness lasting hours to days associated with reduced serum potassium (K+). HypoPP is genetically heterogeneous, with missense mutations of a calcium channel (CaV1.1) or a sodium channel (NaV1.4) accounting for 60% and 20% of cases, respectively. The mechanistic link between CaV1.1 mutations and the ictal loss of muscle excitability during an attack of weakness in Hy...
Stiffness in 1D matrix product states with periodic boundary conditions
Rossini, Davide; Giovannetti, Vittorio; Fazio, Rosario
2011-05-01
We discuss in detail a modified variational matrix product state algorithm for periodic boundary conditions, based on a recent work by Pippan et al (2010 Phys. Rev. B 81 081103(R)), which enables one to study large systems on a ring (composed of N ~ 102 sites). In particular, we introduce a couple of improvements allowing us to enhance the algorithm in terms of stability and reliability. We employ such a method to compute the stiffness of one-dimensional strongly correlated quantum lattice systems. The accuracy of our calculations is tested in the exactly solvable spin-1/2 Heisenberg chain.
Multi-period inventory models with price protection
Ahat, Nurdan
2007-01-01
Cataloged from PDF version of article. In an environment with declining sales prices, retailers (or any reseller) often face the risk of buying high and selling low. In order to limit their channel partners’ exposure to such risks and increase the availability of their products in the marketplace, suppliers often offer price protection. With price protection, a retailer is reimbursed with a percentage of the procurement cost declines, for the inventory that the retailer orde...
EXISTENCE OF PERIODIC SOLUTIONS FOR A DISCRETE-TIME MODEL OF TWO-CELL CNNS
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
We investigate a class of discrete-time model of two-cell cellular neural networks with symmetric template. By using the Lyapunov direct method, La-Salle's invariance principle, we discuss the existence and the stability of periodic solutions. The model considered has attractive 2-periodic and unstable 2-periodic solutions.
Forecasting Daily Time Series using Periodic Unobserved Components Time Series Models
Koopman, Siem Jan; Ooms, Marius
2004-01-01
We explore a periodic analysis in the context of unobserved components time series models that decompose time series into components of interest such as trend and seasonal. Periodic time series models allow dynamic characteristics to depend on the period of the year, month, week or day. In the stand
Forecasting Daily Time Series using Periodic Unobserved Components Time Series Models
Koopman, Siem Jan; Ooms, Marius
2004-01-01
We explore a periodic analysis in the context of unobserved components time series models that decompose time series into components of interest such as trend and seasonal. Periodic time series models allow dynamic characteristics to depend on the period of the year, month, week or day. In the
Model of evaluating the projected payback period in energy preservation
Directory of Open Access Journals (Sweden)
Gorshkov Aleksandr Sergeevich
2015-12-01
Full Text Available Providing energy efficiency of newly designed buildings is an important state task which is considered in EPBD directive and the latest regulations on energy saving. Though reducing energy consumption of the existing building is not less important. The majority of the existing buildings had been built before the implementation of modern energy saving programs. That’s why the volume of energy consumption in the existing buildings is greater than in new buildings. In frames of the given investigation the author considers the problem of forecasting the payback period of investment into reduction of energy consumption in a building. The formula is offered for calculating the projected payback period in energy saving with account for capital costs, calculated or actual value of the achieved energy saving effect, rise in tariffs for energy sources, discounting of the future cash flows and the volume and time for return of credit funds. Basing on the offered calculation methods it is possible to compare the efficiency of different energy saving solutions.
Wang, Tzi-Yuan; Tsai, Yi-Hsuan; Yu, I-Zen; Chang, Te-Sheng
2016-03-01
3'-Hydroxygenistein can be obtained from the biotransformation of genistein by the engineered Pichia pastoris X-33 strain, which harbors a fusion gene composed of CYP57B3 from Aspergillus oryzae and a cytochrome P450 oxidoreductase gene (sCPR) from Saccharomyces cerevisiae. P. pastoris X-33 mutants with higher 3'-hydroxygenistein production were selected using a periodic hydrogen peroxide-shocking strategy. One mutant (P2-D14-5) produced 23.0 mg/l of 3'-hydroxygenistein, representing 1.87-fold more than that produced by the recombinant X-33. When using a 5 L fermenter, the P2-D14-5 mutant produced 20.3 mg/l of 3'- hydroxygenistein, indicating a high potential for industrial-scale 3'-hydroxygenistein production.
Shargel, Benjamin Hertz
2009-01-01
Asymptotic fluctuation theorems are statements of a Gallavotti-Cohen symmetry in the rate function of either the time-averaged entropy production or heat dissipation of a process. Such theorems have been proved for various general classes of continuous-time deterministic and stochastic processes, but always under the assumption that the forces driving the system are time independent, and often relying on the existence of a limiting ergodic distribution. In this paper we extend the asymptotic fluctuation theorem for the first time to inhomogeneous continuous-time processes without a stationary distribution, considering specifically a finite state Markov chain driven by periodic transition rates. We find that for both entropy production and heat dissipation, the usual Gallavotti-Cohen symmetry of the rate function is generalized to an analogous relation between the rate functions of the original process and its corresponding backward process, in which the trajectory and the driving protocol have been time-rever...
Simulation model of metallurgical production management
Directory of Open Access Journals (Sweden)
P. Šnapka
2013-07-01
Full Text Available This article is focused to the problems of the metallurgical production process intensification. The aim is the explaining of simulation model which presents metallurgical production management system adequated to new requirements. The knowledge of a dynamic behavior and features of metallurgical production system and its management are needed to this model creation. Characteristics which determine the dynamics of metallurgical production process are characterized. Simulation model is structured as functional blocks and their linkages with regard to organizational and temporal hierarchy of their actions. The creation of presented simulation model is based on theoretical findings of regulation, hierarchical systems and optimization.
The XXZ model with anti-periodic twisted boundary conditions
Niekamp, Sönke; Frahm, Holger
2009-01-01
We derive functional equations for the eigenvalues of the XXZ model subject to anti-diagonal twisted boundary conditions by means of fusion of transfer matrices and by Sklyanin's method of separation of variables. Our findings coincide with those obtained using Baxter's method and are compared to the recent solution of Galleas. As an application we study the finite size scaling of the ground state energy of the model in the critical regime.
The XXZ model with anti-periodic twisted boundary conditions
Energy Technology Data Exchange (ETDEWEB)
Niekamp, Soenke; Wirth, Tobias; Frahm, Holger [Institut fuer Theoretische Physik, Leibniz Universitaet Hannover, Appelstrasse 2, 30167 Hannover (Germany)
2009-05-15
We derive functional equations for the eigenvalues of the XXZ model subject to anti-diagonal twisted boundary conditions by means of fusion of transfer matrices and by Sklyanin's method of separation of variables. Our findings coincide with those obtained using Baxter's method and are compared to the recent solution of Galleas. As an application we study the finite size scaling of the ground-state energy of the model in the critical regime.
Modeling the polymer product maceration
Ahunov, D. N.; Karpova, M. N.
2014-12-01
The article contains a view of mass transmission simulation procedure conformably to control of manufacturing method's automation, and also is shown a simulator of polymer product maceration process, and results of developed for this simulator realization program system
Investigating the productivity model for clinical nurses.
Dehghan Nayeri, Nahid; Hooshmand Bahabadi, Abbas; Kazemnejad, Anoshirvan
2014-01-01
One of the main objectives of quantitative researches is assessment of models developed by qualitative studies. Models validation through their testing implies that the designed model is representative of the existed facts. Hence, this study was conducted to assess the clinical nurses' productivity model presented for Iranian nurses' productivity. The sample of the study consisted of 360 nurses of Tehran University of Medical Sciences. The research tool was a questionnaire for measuring the components of clinical nurses' productivity. After completing all steps of instrument psychometric and getting answers from the participants, the factors introduced in the questionnaire were named and then Lisrel Path Analysis tests were performed to analyze the components of the model. The results of the model test revealed there is an internal relationship among different components of the model. Regression Analysis showed that each increasing unit in components of the model was to be added to central variable of productivity model -human resource. Model components altogether explained 20 % of clinical nurses' productivity variance. This study found that the important component of productivity is human resources that are reciprocally related to other components of the model. Therefore, it can be stated that the managers can promote the productivity by using efficient strategies to correct human resource patterns.
LAMB FEEDING STRATEGIES DURING THE PRE-WEANING PERIOD IN INTENSIVE MEAT PRODUCTION SYSTEMS
Directory of Open Access Journals (Sweden)
Stela Antas Urbano
2017-05-01
Full Text Available The modern consumer of sheep meat requires uninterrupted market supply with qualitatively standardized meat, without excess fat and with high tenderness, which has encouraged producers to slaughter young sheep. A lamb’s diet during the pre-weaning phase was discussed in this review because it is of great importance for achieving success in a meat production system, given the high speed of lambs’ growth during their first weeks of life. Supplying palatable concentrate in creep-feeders from the first days of life promotes pre-stomach development and adapts the animal to a solid diet consumption; important processes for enhancing animal performance, since nutritional requirements, especially for energy, are high during this period and can only be met by milk for a short time. An early weaning technique can be adopted from 35 days old, when adequate nutritional support is provided. Unweaned lamb slaughtering combined with creep feeding and controlled feeding have superior effects to early abrupt weaning, probably by avoiding the adverse effects generated by post-weaning stress. The use of a milk replacer is seldom reported due to the difficulty in finding specific products for sheep and its high cost. Controlled suckling does not affect the performance of lambs. Further studies investigating lamb feeding strategies need to be developed during the pre-weaning period.
Structural changes and productivity in the crisis period in Romania. The industry case
Directory of Open Access Journals (Sweden)
Anca DACHIN
2013-06-01
Full Text Available The present crisis is a new case study for the theories regarding economic fluctuations. The interpretation of this phenomenon varies from the acceptance of its character of rule in the history of capitalism, which brings corrections to excess in human behaviour, to the emphasis on its uniqueness determined by the effects of unprecedented globalization. The Romanian economy went through the crisis by having persistent structural problems which were partially masked by the expansion during the previous period of sustained economic growth. Considering that productivity is a significant parameter for the competitiveness of the national economy and that the healthy economic growth is a chance for diminishing the gap to other European countries, the paper aims at the identification of the economic activities which have contributed to economic growth until 2008 and of the potential sources of economic recovery in the next period. The research uses the empirical analysis in order to see the effects of the crisis, as well as to understand the signals given by the productivity trend regarding structural changes after the crisis started. Since the industry had a fast recovery in 2011 compared to other EU countries, the analysis is extended to the contribution of this activity to economic growth.
Forecasting coconut production in the Philippines with ARIMA model
Lim, Cristina Teresa
2015-02-01
The study aimed to depict the situation of the coconut industry in the Philippines for the future years applying Autoregressive Integrated Moving Average (ARIMA) method. Data on coconut production, one of the major industrial crops of the country, for the period of 1990 to 2012 were analyzed using time-series methods. Autocorrelation (ACF) and partial autocorrelation functions (PACF) were calculated for the data. Appropriate Box-Jenkins autoregressive moving average model was fitted. Validity of the model was tested using standard statistical techniques. The forecasting power of autoregressive moving average (ARMA) model was used to forecast coconut production for the eight leading years.
Dependability breakeven point mathematical model for production - quality strategy support
Vilcu, Adrian; Verzea, Ion; Chaib, Rachid
2016-08-01
This paper connects the field of dependability system with the production-quality strategies through a new mathematical model based on breakeven points. The novelties consist in the identification of the parameters of dependability system which, in safety control, represents the degree to which an item is capable of performing its required function at any randomly chosen time during its specified operating period disregarding non-operation related influences, as well as the analysis of the production-quality strategies, defining a mathematical model based on a new concept - dependability breakeven points, model validation on datasets and shows the practical applicability of this new approach.
Wolfenson, D; Flamenbaum, I; Berman, A
1988-03-01
Effects of cooling high producing dairy cows during the dry period were examined in 84 pluriparous Israeli-Holstein cows. Cooling was by a combination of wetting and forced ventilation from 0600 to 1800 h until parturition and common management afterwards for both groups. Cooling maintained diurnal increase in rectal temperature within .2 degrees C as compared with .5 degrees C in control cows in warmer months, Mean rectal temperatures at 1400 h in control cows were moderate, within 39.2 degrees C. Cooling did not affect prepartum or postpartum body condition score or mean blood progesterone during the dry period. Results suggested a possible increase in blood progesterone in later pregnancy by cooling during hot weather. Cooling increased mean 150-d milk production by 3.6 kg/d (3.1 kg FCM/d). Prepartum cooling negatively affected first lactation month yield in cows calving in early summer. Prepartum cooling might prevent adaptation to heat and impair subsequent postpartum performance. Prepartum progesterone was not related to milk yield. Calves' birth weight increased by cooling, but the effect was mostly in older cows. Birth weight was related to milk yield, independently of cooling effect, mostly in older cows. Cooling during the dry period might increase milk yield as it does during lactation. Results indicate possible benefit of cooling dry cows even under mild heat stress.
101 Modelling and Forecasting Periodic Electric Load for a ...
African Journals Online (AJOL)
User
2012-01-24
Jan 24, 2012 ... In this work, three models are used to analyze the electric load capacity of a ..... Forecasting electricity prices for a day-ahead pool-based electric energy market. ... Control, Operation and Management, Hong Kong pgs.782–7.
Compact attractors for time-periodic age-structured population models
Directory of Open Access Journals (Sweden)
Pierre Magal
2001-10-01
Full Text Available In this paper we investigate the existence of compact attractors for time-periodic age-structured models. So doing we investigate the eventual compactness of a class of abstract non-autonomous semiflow (non necessarily periodic. We apply this result to non-autonomous age-structured models. In the time periodic case, we obtain the existence of a periodic family of compact subsets that is invariant by the semiflow, and attract the solutions of the system.
Modeling Sustainability in Product Development and Commercialization
Carlson, Robert C.; Rafinejad, Dariush
2008-01-01
In this article, the authors present the framework of a model that integrates strategic product development decisions with the product's impact on future conditions of resources and the environment. The impact of a product on stocks of nonrenewable sources and sinks is linked in a feedback loop to the cost of manufacturing and using the product…
A model for the neural control of pineal periodicity
de Oliveira Cruz, Frederico Alan; Soares, Marilia Amavel Gomes; Cortez, Celia Martins
2016-12-01
The aim of this work was verify if a computational model associating the synchronization dynamics of coupling oscillators to a set of synaptic transmission equations would be able to simulate the control of pineal by a complex neural pathway that connects the retina to this gland. Results from the simulations showed that the frequency and temporal firing patterns were in the range of values found in literature.
Order and Disorder in Product Innovation Models
Pina e Cunha, Miguel; Gomes, Jorge F.S.
2003-01-01
This article argues that the conceptual development of product innovation models goes hand in hand with paradigmatic changes in the field of organization science. Remarkable similarities in the change of organizational perspectives and product innovation models are noticeable. To illustrate how chan
Imagery Intelligence (IMINT) Production Model
1980-01-01
1.2.1 Strategic versus Tactical IMINT. A major issue in oevLloping the moodl of IMINT production involveo the decision to use IMINT processing as...resuurce~a, onu/’or lack of support capabil iiS. The I11 facilIity lufla-gc- iient can provide training or exercises to cormplerenit its active isi~on
Increasing flux rate to shorten leaching period and ramp-up production
Ngantung, Billy; Agustin, Riska; Ravi'i
2017-01-01
J Resources Bolaang Mongondow (JBRM) has operated a dynamic heap leach in its Bakan Gold Mine since late 2013. After successfully surpassing its name plate capacity of 2.6 MT/annum in 2014, the clayey and transition ore become the next operational challenge. The presence of transition and clayey ore requires longer leaching period, hence reducing the leach pad capacity which then caused reduced production. Maintaining or even increasing production with such longer leaching ore types can be done by expanding the leach pad area which means an additional capital investment, and/or shortening the leaching cycle which compromise a portion of gold extraction. JBRM has been successfully increasing the leach pad production from 2.6 MT/annum to 3.8 MT/annum, whilst improving the gold extraction from around 70% to around 80%. This was achieved by managing the operation of the leach pad which is shortening the leach cycle by identifying and combining the optimal flux rate application versus the tonne processed in each cell, at no capital investment for expanding the cell capacity.
Marketing Modeling for New Products
C. Hernández-Mireles (Carlos)
2010-01-01
textabstractThis thesis addresses the analysis of new or very recent marketing data and the introduction of new marketing models. We present a collection of models that are useful to analyze (1) the optimal launch time of new and dominant technologies, (2) the triggers, speed and timing of new produ
Modelling Product Families for Product Configuration Systems with Product Variant Master
DEFF Research Database (Denmark)
Mortensen, Niels Henrik; Hvam, Lars; Haug, Anders
2010-01-01
developed in cooperation with several industrial companies. This article refers to experiences from applying the modelling technique in three different companies. Based upon these experiences, the utility of the product variant master and CRC-cards is evaluated. Significance. Product configuration systems...... are increasingly used in industrial companies as a means for efficient design of customer tailored products. The design and implementation of product configuration systems is a new and challenging task for the industrial companies and calls for a scientifically based framework to support the modelling......This article presents an evaluation of applying a suggested method for modelling product families for product configuration based on theory for modelling mechanical products,systems theory and object-oriented modelling. The modelling technique includes a so-called product variant master and CRC...
The World gas model. A multi-period mixed complementarity model for the global natural gas market
Energy Technology Data Exchange (ETDEWEB)
Egging, Ruud [Dept of Civil and Environmental Engineering, University of Maryland, 1143 Glenn L. Martin Hall, College Park, MD 20742 (United States); Holz, Franziska [DIW Berlin, Mohrenstr. 58, 10117 Berlin (Germany); Gabriel, Steven A. [Dept of Civil and Environmental Engineering, University of Maryland, 1143 Glenn L. Martin Hall, College Park, MD 20742 (United States); DIW Berlin, Mohrenstr. 58, 10117 Berlin (Germany)
2010-10-15
We provide the description, mathematical formulation and illustrative results of the World Gas Model, a multi-period complementarity model for the global natural gas market with explicit consideration of market power in the upstream market. Market players include producers, traders, pipeline and storage operators, LNG (liquefied natural gas) liquefiers and regasifiers as well as marketers. The model data set contains more than 80 countries and regions and covers 98% of world wide natural gas production and consumption. We also include a detailed representation of cross-border natural gas pipelines and constraints imposed by long-term contracts in the LNG market. The model is calibrated to match production and consumption projections from the PRIMES [EC. European energy and transport: trends to 2030-update 2007. Brussels: European Commission; 2008] and POLES models [EC. World energy technology outlook - 2050 (WETO-H2). Brussels: European Commission; 2006] up to 2030. The results of our numerical simulations illustrate how the supply shares of pipeline and LNG in various regions in the world develop very differently over time. LNG will continue to play a major role in the Asian market, also for new importers like China and India. Europe will expand its pipeline import capacities benefiting from its relative proximity to major gas suppliers. (author)
Safe production model for small mines
Institute of Scientific and Technical Information of China (English)
Calizaya F.; Suryanto S.
2008-01-01
Presented a "safe production model" that can be adopted by small mine opera-tors to achieve their production targets safely and efficiently. The model consists of eightelements ranging from management commitment and leadership to safety account-abilityand communication. The model is developed considering the mine operators' resourcelimitations and the workers' training needs. The study concludes with a summary of asample survey that is conducted to validate the model and estimate a parameter for eachmine and determine its position in the safe production scale.
Bergeot, Nicolas; Chevalier, Jean-Marie; Bruyninx, Carine
2015-04-01
Several agencies are routinely monitoring the vertical Total Electron Content (vTEC) using GNSS data. Derived maps are available with different latencies, area extents, and grid/time resolutions. However, no high-resolution maps are publically available over Europe in near real-time. In this frame, the Royal Observatory of Belgium (ROB) developed the ROB-IONO software which takes advantage of the dense EUREF Permanent GNSS Network (EPN) to monitor the ionosphere. The main ROB products consist of ionospheric vTEC maps over Europe and their variability estimated in near real-time every 15 min on 0.5° x 0.5° grids using GPS observations. The maps are available online with a latency of ~3 min in the IONEX format at ftp://gnss.oma.be and as interactive web pages at www.gnss.be. During normal ionospheric activity, the ROB-TEC maps show a good agreement with widely used post-processed global products from IGS, CODE and ESA, with mean differences of 1.3 ± 0.9, 0.6 ± 0.7 and 0.4 ± 1.6 TECu respectively for the period 2012 to mid-2013. For a disturbed period, such as the 2003 Halloween ionospheric storm, the mean differences with IGS, CODE and ESA maps are respectively 0.9 ± 2.2, 0.1 ± 2.0 and 0.6 ± 6.8 TECu, with maximum differences (>38 TECu) occurring during the major phase of the storm. These differences are due to the lower resolution of global products in time and space compared to the ROB-TEC maps. A description of two recent events, on March 17, 2013 and February 27, 2014 highlights the capability of the method adopted to detect in near real-time abnormal ionospheric behaviour over Europe. The potential of the variability maps as an indicator of rapid ionospheric variations during the 15 min of observations is also highlighted. More than 30 ionospheric events associated with Space weather were detected during the period 2012-2014. The ionospheric perturbations are associated with Coronal Mass Ejections (CMEs, ~70% of the time), active geomagnetic conditions
Energy Technology Data Exchange (ETDEWEB)
T.F. Eibert; J.L. Volakis; Y.E. Erdemli
2002-03-03
Hybrid finite element (FE)--boundary integral (BI) analysis of infinite periodic arrays is extended to include planar multilayered Green's functions. In this manner, a portion of the volumetric dielectric region can be modeled via the finite element method whereas uniform multilayered regions can be modeled using a multilayered Green's function. As such, thick uniform substrates can be modeled without loss of efficiency and accuracy. The multilayered Green's function is analytically computed in the spectral domain and the resulting BI matrix-vector products are evaluated via the fast spectral domain algorithm (FSDA). As a result, the computational cost of the matrix-vector products is kept at O(N). Furthermore, the number of Floquet modes in the expansion are kept very few by placing the BI surfaces within the computational unit cell. Examples of frequency selective surface (FSS) arrays are analyzed with this method to demonstrate the accuracy and capability of the approach. One example involves complicated multilayered substrates above and below an inhomogeneous filter element and the other is an optical ring-slot array on a substrate several hundred wavelengths in thickness. Comparisons with measurements are included.
Tanabe, Kana; Kitagawa, Eri; Wada, Misaki; Haraguchi, Atsushi; Orihara, Kanami; Tahara, Yu; Nakao, Atsuhito; Shibata, Shigenobu
2015-09-30
The mammalian circadian clock controls many physiological processes that include immune responses and allergic reactions. Several studies have investigated the circadian regulation of intestinal permeability and tight junctions known to be affected by cytokines. However, the contribution of circadian clock to food allergy symptoms remains unclear. Therefore, we investigated the role of the circadian clock in determining the severity of food allergies. We prepared an ovalbumin food allergy mouse model, and orally administered ovalbumin either late in the light or late in the dark period under light-dark cycle. The light period group showed higher allergic diarrhea and weight loss than the dark period group. The production of type 2 cytokines, IL-13 and IL-5, from the mesenteric lymph nodes and ovalbumin absorption was higher in the light period group than in the dark period group. Compared to the dark period group, the mRNA expression levels of the tight junction proteins were lower in the light period group. We have demonstrated that increased production of type 2 cytokines and intestinal permeability in the light period induced severe food allergy symptoms. Our results suggest that the time of food antigen intake might affect the determination of the severity of food allergy symptoms.
Directory of Open Access Journals (Sweden)
Ming-Feng Yang
2015-01-01
Full Text Available In most commercial transactions, the buyer and vendor may usually agree to postpone payment deadline. During such delayed period, the buyer is entitled to keep the products without having to pay the sale price. However, the vendor usually hopes to receive full payment as soon as possible, especially when the transaction involves valuable items; yet, the buyer would offer a higher purchasing price in exchange of a longer postponement. Therefore, we assumed such permissible delayed period is dependent on the purchasing price. As for the manufacturing side, defective products are inevitable from time to time, and not all of those defective products can be repaired. Hence, we would like to add defective production and repair rate to our proposed model and discuss how these factors may affect profits. In addition, holding cost, ordering cost, and transportation cost will also be considered as we develop the integrated inventory model with price-dependent payment period under the possible condition of defective products. We would like to find the maximum of the joint expected total profit for our model and come up with a suitable inventory policy accordingly. In the end, we have also provided a numerical example to clearly illustrate possible solutions.
Models and Modelling Tools for Chemical Product and Process Design
DEFF Research Database (Denmark)
Gani, Rafiqul
2016-01-01
The design, development and reliability of a chemical product and the process to manufacture it, need to be consistent with the end-use characteristics of the desired product. One of the common ways to match the desired product-process characteristics is through trial and error based experiments......-based framework is that in the design, development and/or manufacturing of a chemical product-process, the knowledge of the applied phenomena together with the product-process design details can be provided with diverse degrees of abstractions and details. This would allow the experimental resources......, are the needed models for such a framework available? Or, are modelling tools that can help to develop the needed models available? Can such a model-based framework provide the needed model-based work-flows matching the requirements of the specific chemical product-process design problems? What types of models...
Statistical Model Checking for Product Lines
DEFF Research Database (Denmark)
ter Beek, Maurice H.; Legay, Axel; Lluch Lafuente, Alberto
2016-01-01
average cost of products (in terms of the attributes of the products’ features) and the probability of features to be (un)installed at runtime. The product lines must be modelled in QFLan, which extends the probabilistic feature-oriented language PFLan with novel quantitative constraints among features......We report on the suitability of statistical model checking for the analysis of quantitative properties of product line models by an extended treatment of earlier work by the authors. The type of analysis that can be performed includes the likelihood of specific product behaviour, the expected...... and on behaviour and with advanced feature installation options. QFLan is a rich process-algebraic specification language whose operational behaviour interacts with a store of constraints, neatly separating product configuration from product behaviour. The resulting probabilistic configurations and probabilistic...
Superfluid stiffness in 1D Matrix Product States with periodic boundary conditions
Rossini, Davide; Fazio, Rosario
2011-01-01
We discuss in details a modified variational matrix-product-state algorithm for periodic boundary conditions, based on a recent work by P. Pippan, S.R. White and H.G. Everts, Phys. Rev. B 81, 081103(R) (2010), which enables one to study large systems on a ring (composed of N ~ 10^2 sites). In particular, we introduce a couple of improvements that allow to enhance the algorithm in terms of stability and reliability. We employ such method to characterize the superfluid phase of one-dimensional strongly correlated quantum lattice systems by means of the superfluid density. The accuracy of our calculations is tested in the exactly solvable spin-1/2 Heisenberg chain.
Directory of Open Access Journals (Sweden)
Anondho Wijanarko
2010-10-01
Full Text Available Chlorella vulgaris Buitenzorg cultivation using three bubble column photo bioreactors arranged in series with a volume of 200 mL for 130 hours shows an increase of biomass production of Chlorella vulgaris Buitenzorg up to 1.20 times and a decrease of the ability of CO2 fixation compared to single reactor at a periodic sun illumination cycle. The operation conditions on cultivation are as following: T, 29.0oC; P,1 atm.; UG, 2.40 m/h; CO2, 10%; Benneck medium; and illumination source by Phillip Halogen Lamp 20W /12V/ 50Hz. Other research parameters such as microbial carbon dioxide transferred rate (qco2, CO2 transferred rate (CTR, energy consumption for cellular formation (Ex, and cultural bicarbonate species concentration [HCO3] also give better results on series of reactor.
Disentangling the Age, Period, and Cohort Effects using a Modeling Approach
Portrait, France; Alessie, R.J.M.; Deeg, Dorly
2002-01-01
Disentangling age, period, and cohort effects in explaining health trends is crucial to assess future prevalences of health disorders. The identification problem -- age, period, and cohort effects are perfectly linearly related -- is tackled by modeling cohort and period effects using lifetime
Disentangling the Age, Period, and Cohort Effects using a Modeling Approach
Portrait, France; Alessie, R.J.M.; Deeg, Dorly
2002-01-01
Disentangling age, period, and cohort effects in explaining health trends is crucial to assess future prevalences of health disorders. The identification problem -- age, period, and cohort effects are perfectly linearly related -- is tackled by modeling cohort and period effects using lifetime macro
Probing the (empirical quantum structure embedded in the periodic table with an effective Bohr model
Directory of Open Access Journals (Sweden)
Wellington Nardin Favaro
2013-01-01
Full Text Available The atomic shell structure can be observed by inspecting the experimental periodic properties of the Periodic Table. The (quantum shell structure emerges from these properties and in this way quantum mechanics can be explicitly shown considering the (semi-quantitative periodic properties. These periodic properties can be obtained with a simple effective Bohr model. An effective Bohr model with an effective quantum defect (u was considered as a probe in order to show the quantum structure embedded in the Periodic Table. u(Z shows a quasi-smoothed dependence of Z, i.e., u(Z ≈ Z2/5 - 1.
Grognard, Frédéric; Bernard, Olivier
2012-01-01
We address the question of optimization of the microalgal biomass long term productivity in the framework of production in photobioreactors under the influence of day/night cycles. For that, we propose a simple bioreactor model accounting for light attenuation in the reactor due to biomass density and obtain the control law that optimizes productivity over a single day through the application of Pontryagin's maximum principle, with the dilution rate being the main control. An important constraint on the obtained solution is that the biomass in the reactor should be at the same level at the beginning and at the end of the day so that the same control can be applied everyday and optimizes some form of long term productivity. Several scenarios are possible depending on the microalgae's strain parameters and the maximal admissible value of the dilution rate: bang-bang or bang-singular-bang control or, if the growth rate of the algae is very strong in the presence of light, constant maximal dilution. A bifurcation...
Product Modelling for Model-Based Maintenance
Houten, van F.J.A.M.; Tomiyama, T.; Salomons, O.W.
1998-01-01
The paper describes the fundamental concepts of maintenance and the role that information technology can play in the support of maintenance activities. Function-Behaviour-State modelling is used to describe faults and deterioration of mechanisms in terms of user perception and measurable quantities.
Anticipated detection of favorable periods for wind energy production by means of information theory
Vogel, Eugenio; Saravia, Gonzalo; Kobe, Sigismund; Schumann, Rolf; Schuster, Rolf
Managing the electric power produced by different sources requires mixing the different response times they present. Thus, for instance, coal burning presents large time lags until operational conditions are reached while hydroelectric generation can react in a matter of some seconds or few minutes to reach the desired productivity. Wind energy production (WEP) can be instantaneously fed to the network to save fuels with low thermal inertia (gas burning for instance), but this source presents sudden variations within few hours. We report here for the first time a method based on information theory to handle WEP. This method has been successful in detecting dynamical changes in magnetic transitions and variations of stock markets. An algorithm called wlzip based on information recognition is used to recognize the information content of a time series. We make use of publically available energy data in Germany to simulate real applications. After a calibration process the system can recognize directly on the WEP data the onset of favorable periods of a desired strength. Optimization can lead to a few hours of anticipation which is enough to control the mixture of WEP with other energy sources, thus saving fuels.
Skill assessment of the PELAGOS global ocean biogeochemistry model over the period 1980–2000
Directory of Open Access Journals (Sweden)
M. Vichi
2009-11-01
Full Text Available Global Ocean Biogeochemistry General Circulation Models are useful tools to study biogeochemical processes at global and large scales under current climate and future scenario conditions. The credibility of future estimates is however dependent on the model skill in capturing the observed multi-annual variability of firstly the mean bulk biogeochemical properties, and secondly the rates at which organic matter is processed within the food web. For this double purpose, the results of a multi-annual simulation of the global ocean biogeochemical model PELAGOS have been objectively compared with multi-variate observations from the last 20 years of the 20th century, both considering bulk variables and carbon production/consumption rates. Simulated net primary production (NPP is comparable with satellite-derived estimates at the global scale and when compared with an independent data-set of in situ observations in the equatorial Pacific. The usage of objective skill indicators allowed us to demonstrate the importance of comparing like with like when considering carbon transformation processes. NPP scores improve substantially when in situ data are compared with modeled NPP which takes into account the excretion of freshly-produced dissolved organic carbon (DOC. It is thus recommended that DOC measurements be performed during in situ NPP measurements to quantify the actual production of organic carbon in the surface ocean. The chlorophyll bias in the Southern Ocean that affects this model as well as several others is linked to the inadequate representation of the mixed layer seasonal cycle in the region. A sensitivity experiment confirms that the artificial increase of mixed layer depths towards the observed values substantially reduces the bias. Our assessment results qualify the model for studies of carbon transformation in the surface ocean and metabolic balances. Within the limits of the model assumption and known biases, PELAGOS indicates a net
Xu, Ming; Jiao, Yan; Li, Xiaoming; Cao, Qingfeng; Wang, Xiaoyang
2015-01-01
This paper presents a multi-period optimization model for high margin and zero salvage products in online distribution channels with classifying customers based on number of products required. Taking hotel customers as an example, one is regular customers who reserve rooms for one day, and the other is long term stay (LTS) customers who reserve rooms for a number of days. LTS may guarantee a specific amount of demand and generate opportunity income for a certain number of periods, meanwhile with risk of punishment incurred by overselling. By developing an operational optimization model and exploring the effects of parameters on optimal decisions, we suggest that service providers should make decisions based on the types of customers, number of products required, and duration of multi-period to reduce the loss of reputation and obtain more profit; at the same time, multi-period buying customers should buy products early. Finally, the paper conducts a numerical experiment, and the results are consistent with prevailing situations.
Xu, Ming; Jiao, Yan; Li, Xiaoming; Cao, Qingfeng; Wang, Xiaoyang
2015-01-01
This paper presents a multi-period optimization model for high margin and zero salvage products in online distribution channels with classifying customers based on number of products required. Taking hotel customers as an example, one is regular customers who reserve rooms for one day, and the other is long term stay (LTS) customers who reserve rooms for a number of days. LTS may guarantee a specific amount of demand and generate opportunity income for a certain number of periods, meanwhile with risk of punishment incurred by overselling. By developing an operational optimization model and exploring the effects of parameters on optimal decisions, we suggest that service providers should make decisions based on the types of customers, number of products required, and duration of multi-period to reduce the loss of reputation and obtain more profit; at the same time, multi-period buying customers should buy products early. Finally, the paper conducts a numerical experiment, and the results are consistent with prevailing situations. PMID:26147663
Directory of Open Access Journals (Sweden)
Ming Xu
Full Text Available This paper presents a multi-period optimization model for high margin and zero salvage products in online distribution channels with classifying customers based on number of products required. Taking hotel customers as an example, one is regular customers who reserve rooms for one day, and the other is long term stay (LTS customers who reserve rooms for a number of days. LTS may guarantee a specific amount of demand and generate opportunity income for a certain number of periods, meanwhile with risk of punishment incurred by overselling. By developing an operational optimization model and exploring the effects of parameters on optimal decisions, we suggest that service providers should make decisions based on the types of customers, number of products required, and duration of multi-period to reduce the loss of reputation and obtain more profit; at the same time, multi-period buying customers should buy products early. Finally, the paper conducts a numerical experiment, and the results are consistent with prevailing situations.
Uses and Limitations of Scientific Models: The Periodic Table as an Inductive Tool.
Ben-Zvi, Nava; Genut, Sara
1998-01-01
Demonstrates that scientific laws about nature and their representative models, as taught and described by theory, are often different from the method as practiced. Focuses on the use of the Periodic Table as a scientific model. Contains 26 references. (DDR)
Zhang, Zhao; Sahoo, Sharmistha; Teo, Jeffrey
We mimic the massless surface Majorana's of topological superconductors by coupled wire models in two spatial dimensions, and introduce many-body gapping interactions that preserve time reversal symmetry. Coupling with a Z2 gauge theory, the symmetric gapped surface generically carries a non-trivial GN topological order, where N is the number of Majorana species and GN is some SO(r)1 or SO(3)3 -like topological state. These form a 32-fold periodic class GN ≅GN + 32 , and a Z32 relative tensor product structure GN1⊗bGN2 ≅GN1 +N2 by anyon condensation. We present the anyon structures of these topological states, and understand the topological orders through bulk-boundary correspondence and the Wilson structures on a torus geometry.
A physiological production model for cacao : results of model simulations
Zuidema, P.A.; Leffelaar, P.A.
2002-01-01
CASE2 is a physiological model for cocoa (Theobroma cacao L.) growth and yield. This report introduces the CAcao Simulation Engine for water-limited production in a non-technical way and presents simulation results obtained with the model.
A physiological production model for cacao : results of model simulations
Zuidema, P.A.; Leffelaar, P.A.
2002-01-01
CASE2 is a physiological model for cocoa (Theobroma cacao L.) growth and yield. This report introduces the CAcao Simulation Engine for water-limited production in a non-technical way and presents simulation results obtained with the model.
Holm, J. A.; Chambers, J. Q.; Collins, W.
2013-12-01
Uncertainties surrounding vegetation and carbon responses to increased disturbance rates associated with climate change remains a major global change issue for Amazon forests. To help quantify the impacts of increased disturbances on climate and the earth system, the fidelity of tree mortality and disturbance algorithms in global land surface models (here the Community Land Model, CLM) warrant critical evaluation. In order to address this issue, we parameterized and calibrated ZELIG-TROP, a dynamic vegetation gap model, to simulate a complex Central Amazon forest toward improving disturbance-recovery processes in CLM. To evaluate the long-term consequences of increased disturbance rates in ZELIG-TROP and CLM for a Central Amazon rainforest, we 1) doubled background tree mortality rates (i.e., high disturbance treatment), and 2) applied a periodic disturbance treatment of removing 20% of stems every 50 years (i.e., periodic treatment) and compared model results. For the high disturbance treatment, ZELIG-TROP predicted that AGB and ANPP decreased by an average of 110 Mg ha-1 and 0.48 Mg C ha-1 yr-1 respectively (41.9% and 7.7%). The net carbon loss due to the periodic treatment, with four large-scale disturbances, was not as extreme as the loss from the high disturbance treatment, due to recovery dynamics. AGB only decreased by 15.9% (vs. 41.9%), however ANPP decreased by 19% (vs. 7.7%). For the high disturbance treatment in ZELIG-TROP, there were a higher proportion of smaller stems and a decrease in larger stems. This resulted in a decrease in coarse litter (trunks and large branches >10 cm in diameter) production rates (Mg C ha-1 yr-1) by 11.5%. For the periodic disturbance the average coarse litter production rates increased by 11.2% due to the four large-scale disturbance events. A comparison of the biomass response of ZELIG-TROP and CLM from simulated disturbance and recovery events displayed the same pattern between the two models, and for both disturbance
Existence of almost periodic solution of a model of phytoplankton allelopathy with delay
Abbas, Syed; Mahto, Lakshman
2012-09-01
In this paper we discuss a non-autonomous two species competitive allelopathic phytoplankton model in which both species are producing chemical which stimulate the growth of each other. We have studied the existence and uniqueness of an almost periodic solution for the concerned model system. Sufficient conditions are derived for the existence of a unique almost periodic solution.
Production management using the EFQM Excellence Model
Directory of Open Access Journals (Sweden)
Janja Škedel
2016-09-01
Full Text Available Research Question (RQ: Comparison of production management using the EFQM Excellence Model. Purpose: The aim of the research is based on a comparison of production management using the EFQM Excellence Model, to establish identity and difference. The aim is to improve the management of production and by using the model closer to excellence. Method: An identification method of benchmarking. Results: The results show tolerance, which represent an opportunity to improve production management with excellence. Organization: If we take into account the results of the organization, this would be an asset to the organization. Society: Method comparisons can also be used in the wider environment. Originality: The survey is unique and the first of its kind in the manufacturing organization. Limitations/Future Research: With this research we will gain improvements in production management through design excellence.
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
[Objective] The aim was to study the climate changes and countermeasures for meteorological disasters during production period in vegetable greenhouse in northern Shenyang. [Method] By dint of local climate data in recent 38 years and using the conventional method of mathematical statistics, the climate changes and countermeasures for meteorological disasters during production period in vegetable greenhouse in northern Shenyang were expounded. [Result] In general, the sunshine condition in new area of Sheny...
Hybrid simulation models of production networks
Kouikoglou, Vassilis S
2001-01-01
This book is concerned with a most important area of industrial production, that of analysis and optimization of production lines and networks using discrete-event models and simulation. The book introduces a novel approach that combines analytic models and discrete-event simulation. Unlike conventional piece-by-piece simulation, this method observes a reduced number of events between which the evolution of the system is tracked analytically. Using this hybrid approach, several models are developed for the analysis of production lines and networks. The hybrid approach combines speed and accuracy for exceptional analysis of most practical situations. A number of optimization problems, involving buffer design, workforce planning, and production control, are solved through the use of hybrid models.
Modelling Configuration Knowledge in Heterogeneous Product Families
DEFF Research Database (Denmark)
Queva, Matthieu Stéphane Benoit; Männistö, Tomi; Ricci, Laurent
2011-01-01
Product configuration systems play an important role in the development of Mass Customisation. The configuration of complex product families may nowadays involve multiple design disciplines, e.g. hardware, software and services. In this paper, we present a conceptual approach for modelling the va...
Modeling Fission Product Sorption in Graphite Structures
Energy Technology Data Exchange (ETDEWEB)
Szlufarska, Izabela [University of Wisconsin, Madison, WI (United States); Morgan, Dane [University of Wisconsin, Madison, WI (United States); Allen, Todd [University of Wisconsin, Madison, WI (United States)
2013-04-08
The goal of this project is to determine changes in adsorption and desorption of fission products to/from nuclear-grade graphite in response to a changing chemical environment. First, the project team will employ principle calculations and thermodynamic analysis to predict stability of fission products on graphite in the presence of structural defects commonly observed in very high- temperature reactor (VHTR) graphites. Desorption rates will be determined as a function of partial pressure of oxygen and iodine, relative humidity, and temperature. They will then carry out experimental characterization to determine the statistical distribution of structural features. This structural information will yield distributions of binding sites to be used as an input for a sorption model. Sorption isotherms calculated under this project will contribute to understanding of the physical bases of the source terms that are used in higher-level codes that model fission product transport and retention in graphite. The project will include the following tasks: Perform structural characterization of the VHTR graphite to determine crystallographic phases, defect structures and their distribution, volume fraction of coke, and amount of sp2 versus sp3 bonding. This information will be used as guidance for ab initio modeling and as input for sorptivity models; Perform ab initio calculations of binding energies to determine stability of fission products on the different sorption sites present in nuclear graphite microstructures. The project will use density functional theory (DFT) methods to calculate binding energies in vacuum and in oxidizing environments. The team will also calculate stability of iodine complexes with fission products on graphite sorption sites; Model graphite sorption isotherms to quantify concentration of fission products in graphite. The binding energies will be combined with a Langmuir isotherm statistical model to predict the sorbed concentration of fission
Directory of Open Access Journals (Sweden)
Cláudio Henrique de Almeida Oliveira
2013-12-01
Full Text Available Twenty-five adult crossbred goats, divided in two groups, were fed over a period of 16 months with diets based on Tifton hay and concentrate feed with (DCO or without (WDCO detoxified castor bean meal as a substitute for soybean meal. Throughout 480 days, blood samples were taken to measure lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, urea, albumin and creatinine. The animals were euthanized, and the anatomical components (lungs, heart, spleen, liver, kidneys, tongue, empty stomach, empty intestines, omentum, cardiac and renal adipose tissue, carcass and commercial cuts (shoulder, ham, loin, ribs and neck were weighed. Thereafter, an anatomic dissection of the loin was performed, separating the muscle, adipose and bone tissues. On the muscular part of the loin, longissimus dorsi, the proximate composition, fatty acid profile and the expression of SEW-1, IGF-I and IGF-II were analyzed. A higher incidence of bone tissue was observed in the anatomical dissections of the loin and a lower incidence of fat in the proximate composition of the longissimus dorsi of the DCO group compared to the WDCO group (p<0.05. The expression of the IGF-II and SEW-1 genes was higher (p<0.001 for each in the muscle tissue of the DCO animals. Thus, using detoxified castor bean meal for long periods does not produce significant changes in the anatomical composition of the loin or the proximate composition of the longissimus dorsi. However, the differences in gene expression suggest the need for new investigations and care when using this product for animal feeding.
Model based sustainable production of biomethane
Biernacki, Piotr
2014-01-01
The main intention of this dissertation was to evaluate sustainable production of biomethane with use of mathematical modelling. To achieve this goal, widely acknowledged models like Anaerobic Digestion Model No.1 (ADM1), describing anaerobic digestion, and electrolyte Non-Random Two Liquid Model (eNRTL), for gas purification, were utilized. The experimental results, batch anaerobic digestion of different substrates and carbon dioxide solubility in 2-(Ethylamino)ethanol, were used to determin...
Forecast of Grain Production of China during the Twelfth Five-Year Plan Period
Institute of Scientific and Technical Information of China (English)
2011-01-01
According to the latest revised agricultural economic statistical data in China Statistical Yearbook-2010,by selecting and establishing the square root-treated grey model,the empirical analysis and forecast research on the grain output of China from 2011 to 2015 are conducted.The results show that the grain output of China in 2011 will reach 557.739 million tons,and it will break through 600 million tons at 605.617 million tons in 2015.The persistent and stable grain output will ensure that the national economy develops in normal during the twelfth five-year plan period and remit the world grain crisis efficiently;meanwhile,the problem of exorbitant grain prices should be remitted in some level.
78 FR 29139 - Medicare Program; Bundled Payments for Care Improvement Model 1 Open Period
2013-05-17
... participation in Model 1 of the Bundled Payments for Care Improvement initiative. DATES: Model 1 of the Bundled Payments for Care Improvement Deadline: Interested organizations must submit a Model 1 Open Period... regarding Model 1 of the Bundled Payments for Care Improvement initiative. For additional information...
Dynamical Model of Weak Pion Production Reactions
Sato, T; Lee, T S H
2003-01-01
The dynamical model of pion electroproduction has been extended to investigate the weak pion production reactions. The predicted cross sections of neutrino-induced pion production reactions are in good agreement with the existing data. We show that the renormalized(dressed) axial N-$\\Delta$ form factor contains large dynamical pion cloud effects and this renormalization effects are crucial in getting agreement with the data. We conclude that the N-$\\Delta$ transitions predicted by the constituent quark model are consistent with the existing neutrino induced pion production data in the $\\Delta$ region.
Moeck, Christian; Von Freyberg, Jana; Schrimer, Maria
2016-04-01
An important question in recharge impact studies is how model choice, structure and calibration period affect recharge predictions. It is still unclear if a certain model type or structure is less affected by running the model on time periods with different hydrological conditions compared to the calibration period. This aspect, however, is crucial to ensure reliable predictions of groundwater recharge. In this study, we quantify and compare the effect of groundwater recharge model choice, model parametrization and calibration period in a systematic way. This analysis was possible thanks to a unique data set from a large-scale lysimeter in a pre-alpine catchment where daily long-term recharge rates are available. More specifically, the following issues are addressed: We systematically evaluate how the choice of hydrological models influences predictions of recharge. We assess how different parameterizations of models due to parameter non-identifiability affect predictions of recharge by applying a Monte Carlo approach. We systematically assess how the choice of calibration periods influences predictions of recharge within a differential split sample test focusing on the model performance under extreme climatic and hydrological conditions. Results indicate that all applied models (simple lumped to complex physically based models) were able to simulate the observed recharge rates for five different calibration periods. However, there was a marked impact of the calibration period when the complete 20 years validation period was simulated. Both, seasonal and annual differences between simulated and observed daily recharge rates occurred when the hydrological conditions were different to the calibration period. These differences were, however, less distinct for the physically based models, whereas the simpler models over- or underestimate the observed recharge depending on the considered season. It is, however, possible to reduce the differences for the simple models by
Directory of Open Access Journals (Sweden)
S. M. Seyedhosseini
2014-01-01
Full Text Available In many conventional supply chains, production planning and distribution planning are treated separately. However, it is now demonstrated that they are mutually related problems that must be tackled in an integrated way. Hence, in this paper a new integrated production and distribution planning model for perishable products is formulated. The proposed model considers a supply chain network consisting of a production facility and multiple distribution centers. The facility produces a single perishable product that is storable only for predetermined periods. A homogenous fleet of vehicles is responsible for delivering the product from facility to distribution centers. The decisions to be made are the production quantities, the distribution centers that must be visited, and the quantities to be delivered to them. The objective is to minimize the total cost, where the trip minimization is considered simultaneously. As the proposed formulation is computationally complex, a heuristic method is developed to tackle the problem. In the developed method, the problem is divided into production submodel and distribution submodel. The production submodel is solved using LINGO, and a particle swarm heuristic is developed to tackle distribution submodel. Efficiency of the algorithm is proved through a number of randomly generated test problems.
Product modelling in the seafood industry
DEFF Research Database (Denmark)
Jonsdottir, Stella; Vesterager, Johan
1997-01-01
assessments, speed up the process and ensure a constant renewal of the seafood products. The objective, therefore, is to estimate the suitability of the CE, and especially CE through product modelling, in the seafood industry as a means to obtain an integration of the entire chain, i.e., a business and market...... based integration obtained by the CE approach and tools. It is described how the knowledge and information of a seafood product can be modelled by using object oriented techniques.......The paper addresses the aspects of Concurrent Engineering (CE) as a means to obtain integrated product development in the seafood industry. It is assumed that the future New Product Development (NPD) in seafood industry companies will shift from being retailer driven and reactive to be more company...
Periodical capacity setting methods for make-to-order multi-machine production systems.
Altendorfer, Klaus; Hübl, Alexander; Jodlbauer, Herbert
2014-08-18
The paper presents different periodical capacity setting methods for make-to-order, multi-machine production systems with stochastic customer required lead times and stochastic processing times to improve service level and tardiness. These methods are developed as decision support when capacity flexibility exists, such as, a certain range of possible working hours a week for example. The methods differ in the amount of information used whereby all are based on the cumulated capacity demand at each machine. In a simulation study the methods' impact on service level and tardiness is compared to a constant provided capacity for a single and a multi-machine setting. It is shown that the tested capacity setting methods can lead to an increase in service level and a decrease in average tardiness in comparison to a constant provided capacity. The methods using information on processing time and customer required lead time distribution perform best. The results found in this paper can help practitioners to make efficient use of their flexible capacity.
Directory of Open Access Journals (Sweden)
R.M.R. Sousa
2012-02-01
Full Text Available The performance of Nile tilapia (Oreochromis niloticus raised in cages furnished with an automatic dispenser, supplied at different frequencies (once per hour and once every two hours and periods (daytime, nighttime and both was evaluated. Eighteen 1.0m³ cages were placed into a 2000m² pond, two meters deep with a 5% water exchange. One hundred and seventy tilapias, with initial weight of 16.0±4.9g, were dispersed into each 1m³ cage and the feed ration was adjusted every 21 days with biometry. Data was collected from March to July (autumn and winter. Significant difference to final weight (P<0.05 among treatments was observed. The increase in feeding frequency improves the productive performance of Nile tilapias in cages and permitted better management of the food. The better feed conversion rate for high feeding frequency (24 times day-1 can result in saving up to 360kg of food for each ton of fish produced, increasing the economic sustenance for tilapia culture and suggesting less environmental pollution.
A deterministic aggregate production planning model considering quality of products
Madadi, Najmeh; Yew Wong, Kuan
2013-06-01
Aggregate Production Planning (APP) is a medium-term planning which is concerned with the lowest-cost method of production planning to meet customers' requirements and to satisfy fluctuating demand over a planning time horizon. APP problem has been studied widely since it was introduced and formulated in 1950s. However, in several conducted studies in the APP area, most of the researchers have concentrated on some common objectives such as minimization of cost, fluctuation in the number of workers, and inventory level. Specifically, maintaining quality at the desirable level as an objective while minimizing cost has not been considered in previous studies. In this study, an attempt has been made to develop a multi-objective mixed integer linear programming model that serves those companies aiming to incur the minimum level of operational cost while maintaining quality at an acceptable level. In order to obtain the solution to the multi-objective model, the Fuzzy Goal Programming approach and max-min operator of Bellman-Zadeh were applied to the model. At the final step, IBM ILOG CPLEX Optimization Studio software was used to obtain the experimental results based on the data collected from an automotive parts manufacturing company. The results show that incorporating quality in the model imposes some costs, however a trade-off should be done between the cost resulting from producing products with higher quality and the cost that the firm may incur due to customer dissatisfaction and sale losses.
Directory of Open Access Journals (Sweden)
Mohammad Amirkhan
2015-09-01
Full Text Available The supply chain network design has attracted the attention of many researchers during recent years. This paper presents a new bi-objective mixed-integer linear programming (MILP model to integrate procurement, production and distribution planning under uncertainty. This model is set up for the network of a multi-echelon, multi-product, multi-channel, multi-period supply chain with regard to two conflicting objectives, which minimize the costs and minimize the sum of backorders and surpluses of products in all periods using “activity-based costing and the total cost of ownership” and “JIT” concepts, respectively. To solve the presented model, an interactive fuzzy approach is used. The associated results show the amount of purchasing of each supplier, the quantity of producing, the inventory of raw materials and products, backorder or surplus delivery of goods, the mode of transportation, the amount of goods transported between facilities and suppliers used in each period. In addition, a numerical example is presented to demonstrate the applicability of the presented model and exhibit the efficiency of the proposed interactive fuzzy approach. Finally, the results and conclusion are provided.
Revised Reynolds Stress and Triple Product Models
Olsen, Michael E.; Lillard, Randolph P.
2017-01-01
Revised versions of Lag methodology Reynolds-stress and triple product models are applied to accepted test cases to assess the improvement, or lack thereof, in the prediction capability of the models. The Bachalo-Johnson bump flow is shown as an example for this abstract submission.
Modelling Fungal Fermentations for Enzyme Production
DEFF Research Database (Denmark)
Albæk, Mads Orla; Gernaey, Krist; Hansen, Morten S.
We have developed a process model of fungal fed-batch fermentations for enzyme production. In these processes, oxygen transfer rate is limiting and controls the substrate feeding rate. The model has been shown to describe cultivations of both Aspergillus oryzae and Trichoderma reesei strains in 550...
DEFF Research Database (Denmark)
Riis, Jesper; Hansen, Benjamin Loer; Hvam, Lars
2003-01-01
The article presents a framework for product knowledge and product related knowledge which can be used to support the product modelling process which is needed for developing IT systems. These IT systems are important tools for many companies when they aim at achieving mass customization and pers......The article presents a framework for product knowledge and product related knowledge which can be used to support the product modelling process which is needed for developing IT systems. These IT systems are important tools for many companies when they aim at achieving mass customization...... on experience from product modelling projects in several companies. Among them for example companies manufacturing electronic switchboards, spray dryer systems and air conditioning equipment. The framework is divided into three views: the product knowledge view, the life phase system view and the transformation...... process view (“the meeting”). The persons (rolls) involved in the product modelling process are for example: domain experts, change managers, model managers, project leaders, technical facilitators, process managers and software programmers. They need a framework during the product modelling process...
Behavior and Design Intent Based Product Modeling
Directory of Open Access Journals (Sweden)
László Horváth
2004-11-01
Full Text Available A knowledge based modeling of mechanical products is presented for industrial CAD/CAM systems. An active model is proposed that comprise knowledge from modeling procedures, generic part models and engineers. Present day models of mechanical systems do not contain data about the background of human decisions. This situation motivated the authors at their investigations on exchange design intent information between engineers. Their concept was extending of product models to be capable of description of design intent information. Several human-computer and human-human communication issues were considered. The complex communication problem has been divided into four sub-problems, namely communication of human intent source with the computer system, representation of human intent, exchange of intent data between modeling procedures and communication of the represented intent with humans. Paper discusses the scenario of intelligent modeling based engineering. Then key concepts for the application of computational intelligence in computer model based engineering systems are detailed including knowledge driven models as well as areas of their application. Next, behavior based models with intelligent content involving specifications and knowledge for the design processes are emphasized and an active part modeling is proposed and possibilities for its application are outlined. Finally, design intent supported intelligent modeling is discussed.
Periodicity in cell dynamics in some mathematical models for the treatment of leukemia
Halanay, A.
2012-11-01
A model for the evolution of short-term hematopoietic stem cells and of leukocytes in leucemia under periodic treatment is introduced. It consists of a system of periodic delay differential equations and takes into consideration the asymmetric division. A guiding function is used, together with a theorem of Krasnoselskii, to prove the existence of a strictly positive periodic solution and its stability is investigated.
Quasi-periodic Henon-like attractors in the Lorenz-84 climate model with seasonal forcing
Broer, HW; Vitolo, R; Simo, C; Dumortier, F; Broer, H; Mawhin, J; Vanderbauwhede, A; Lunel, SV
2005-01-01
A class of strange attractors is described, occurring in a low-dimensional model of general atmospheric circulation. The differential equations of the system are subject to periodic forcing, where the period is one year - as suggested by Lorenz in 1984. The dynamics of the system is described in ter
Periodic orbits for seasonal SIRS models with non-linear incidence rates
Directory of Open Access Journals (Sweden)
Laura Rocio Gonzalez-Ramirez
2015-12-01
Full Text Available In this work, we prove the existence of periodic solutions for a seasonally-dependent SIRS model using Leray-Schauder degree theory. We obtain criteria for the uniqueness and asymptotic stability of the periodic solution of the system. We also present suitable examples of a seasonal epidemiological disease.
Periodic Solutions of a Delayed Predator-Prey Model with Stage Structure for Prey
Institute of Scientific and Technical Information of China (English)
Rui Xu; Lan-sun Chen; Fei-long Hao
2004-01-01
A periodic predator-prey model with stage structure for prey and time delays due to negative feedbackand gestation of predator is proposed. By using Gaines and Mawhin's continuation theorem of coincidencedegree theory, su.cient conditions are derived for the existence of positive periodic solutions to the proposedmodel. Numerical simulations are presented to illustrate the feasibility of our main result.
OPTIMAL CONTROL PROBLEM FOR A PERIODIC PREDATOR-PREY MODEL WITH AGE-DEPENDENCE
Institute of Scientific and Technical Information of China (English)
无
2012-01-01
In this paper,we investigate optimal policy for periodic predator-prey system with age-dependence.Namely,we consider the model with periodic vital rates and initial distribution.The existence of optimal control strategy is discussed by Mazur's theorem and optimality condition is derived by means of normal cone.
Global Attractivity of Positive Periodic Solutions for a Survival Model of Red Blood Cells
Institute of Scientific and Technical Information of China (English)
Xin-min Wu; Jing-wen Li
2007-01-01
In this paper, we deal with a model for the survival of red blood cells with periodic coefficients x′(t)=- μ(t)x(t)+P(t)e-γ(t)x(t-(τ))＞0. (*)A new sufficient condition for global attractivity of positive periodic solutions of Eq.(*) is obtained. Our criterion improves corresponding result obtained by Li and Wang in 2005.
Product modelling in the seafood industry
DEFF Research Database (Denmark)
Jonsdottir, Stella; Vesterager, Johan
1997-01-01
driven and proactive to comply with the increasing competition, in such a way that the fish processor issues new products covering both the current and especially latent future consumer demands. This implies a need for new systematic approaches in the NPD as procedures and tools, which integrate...... assessments, speed up the process and ensure a constant renewal of the seafood products. The objective, therefore, is to estimate the suitability of the CE, and especially CE through product modelling, in the seafood industry as a means to obtain an integration of the entire chain, i.e., a business and market...... based integration obtained by the CE approach and tools. It is described how the knowledge and information of a seafood product can be modelled by using object oriented techniques....
Feedback model evaluation of high-mix product manufacturing
King, Dion; Cheng, Mingjen; Lu, Aho; Mao, Zhibiao; Liang, Curtis
2006-03-01
As the patterns are getting smaller, the difficulty to control a margin-tight process expands exponentially. The use of the Automated Process Control (APC), therefore, becomes a widely employed mean in photolithography process to control overlay and CD variations. The accuracy of APC is dependent upon the amount of the previous process data. However, in a foundry with high-mix products it is typical that there are not enough historic data points for accurate calculation of process parameters for a low volume product. The consequence is the high rework rate of pilot runs and test runes due to poor process parameter prediction for overlay. Several studies of the method for predicting the overlay correction have been reported. The key to build a good prediction model is to break the overlay errors down to several parts. Some are equipment or technology related errors, which are shared by all products. Others are the characteristic for certain products, for instance, mask error or special alignment marks. In the production environment the former parts are updated in real time by data feedback from processing all kinds of products. The low volume products or pilot products can share the information. Thus we can achieve a more accurate control or prediction for a new product. In this paper we provide a new model for predicting the process parameter settings of overlay for a pilot run or a product not being run on a tool for a long period of time. This new model is a Simplified Cerebellar Manipulation Arithmetic Controller (SCMAC), which is one kind of Neural Network (NN) model. We assume each part of overlay errors is a cell in SCMAC and build the whole cell table by using this assumption. The final overlay correction value is the sum of a group of cells, which is activated by one lot information. We will also present the details of the building and training of this new SCMAC model. The prediction accuracy of SCMAC in overlay parameters is also evaluated. According to
Product with service, technology with business model
DEFF Research Database (Denmark)
Sakao, Tomohiko; McAloone, Tim C.
2011-01-01
Looking back over the last decade, the importance of an expanded understanding of engineering design has been shared within the engineering design community. Presented concepts and methods to support such expansion include Functional Product Development, Service Engineering, and Product/Service-S...... promising concept beyond PSS design; via an integrated development of technology and business model. This can be of particular interest for further research, especially due to its high freedom for designers....
A chaotic agricultural machines production growth model
Jablanović, Vesna D.
2011-01-01
Chaos theory, as a set of ideas, explains the structure in aperiodic, unpredictable dynamic systems. The basic aim of this paper is to provide a relatively simple agricultural machines production growth model that is capable of generating stable equilibrium, cycles, or chaos. A key hypothesis of this work is based on the idea that the coefficient π = 1 + α plays a crucial role in explaining local stability of the agricultural machines production, where α is an autonomous growth rate of the ag...
Clinical Productivity System - A Decision Support Model
Bennett, Casey C
2012-01-01
Purpose: This goal of this study was to evaluate the effects of a data-driven clinical productivity system that leverages Electronic Health Record (EHR) data to provide productivity decision support functionality in a real-world clinical setting. The system was implemented for a large behavioral health care provider seeing over 75,000 distinct clients a year. Design/methodology/approach: The key metric in this system is a "VPU", which simultaneously optimizes multiple aspects of clinical care. The resulting mathematical value of clinical productivity was hypothesized to tightly link the organization's performance to its expectations and, through transparency and decision support tools at the clinician level, affect significant changes in productivity, quality, and consistency relative to traditional models of clinical productivity. Findings: In only 3 months, every single variable integrated into the VPU system showed significant improvement, including a 30% rise in revenue, 10% rise in clinical percentage, a...
Directory of Open Access Journals (Sweden)
Hugo Sandoval
2017-07-01
Full Text Available Some interpretations frequently argue that three Disability Models (DM (Charity, Medical/Rehabilitation, and Social correspond to historical periods in terms of chronological succession. These views permeate a priori within major official documents on the subject in Mexico. This paper intends to test whether this association is plausible by applying a timeline method. A document search was made with inclusion and exclusion criteria in databases to select representative studies with which to depict milestones in the timelines for each period. The following is demonstrated: 1 models should be considered as categories of analysis and not as historical periods, in that the prevalence of elements of the three models is present to date, and 2 the association between disability models and historical periods results in teleological interpretations of the history of disability in Mexico.
Structure and vibrational spectra of a model of a-Si:H with periodic boundary conditions
Energy Technology Data Exchange (ETDEWEB)
Winer, K.; Wooten, F.
1983-08-01
A ball-and -stick model of a-Si:H with periodic boundary conditions has been constructed. A computer replica of the structure has been relaxed and the density, radial distribution function and vibrational spectra calculated.
Positive Almost Periodic Solutions for a Time-Varying Fishing Model with Delay
Directory of Open Access Journals (Sweden)
Xia Li
2011-01-01
Full Text Available This paper is concerned with a time-varying fishing model with delay. By means of the continuation theorem of coincidence degree theory, we prove that it has at least one positive almost periodic solution.
Periodicity in a "Food-limited" Population Model with Toxicants and Time Delays
Institute of Scientific and Technical Information of China (English)
Meng Fan; Ke Wang
2002-01-01
With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree, we study the global existence of positive periodic solutions of a "food-limited" population model with toxicants and time delays. Some new results are obtained.
Institute of Scientific and Technical Information of China (English)
Zheng-qiu ZHANG; Zhi-cheng WANG
2007-01-01
In this paper, the existence of two positive periodic solutions for a generalized delayed population model with an exploited term is established by using the continuation theorem of the coincidence degree theory.
A model for methane production in sewers.
Chaosakul, Thitirat; Koottatep, Thammarat; Polprasert, Chongrak
2014-09-19
Most sewers in developing countries are combined sewers which receive stormwater and effluent from septic tanks or cesspools of households and buildings. Although the wastewater strength in these sewers is usually lower than those in developed countries, due to improper construction and maintenance, the hydraulic retention time (HRT) could be relatively long and resulting considerable greenhouse gas (GHG) production. This study proposed an empirical model to predict the quantity of methane production in gravity-flow sewers based on relevant parameters such as surface area to volume ratio (A/V) of sewer, hydraulic retention time (HRT) and wastewater temperature. The model was developed from field survey data of gravity-flow sewers located in a peri-urban area, central Thailand and validated with field data of a sewer system of the Gold Coast area, Queensland, Australia. Application of this model to improve construction and maintenance of gravity-flow sewers to minimize GHG production and reduce global warming is presented.
STEP - Product Model Data Sharing and Exchange
DEFF Research Database (Denmark)
Kroszynski, Uri
1998-01-01
- Product Data Representation and Exchange", featuring at present some 30 released parts, and growing continuously. Many of the parts are Application Protocols (AP). This article presents an overview of STEP, based upon years of involvement in three ESPRIT projects, which contributed to the development......During the last fifteen years, a very large effort to standardize the product models employed in product design, manufacturing and other life-cycle phases has been undertaken. This effort has the acronym STEP, and resulted in the International Standard ISO-10303 "Industrial Automation Systems...
Energy Technology Data Exchange (ETDEWEB)
Belmonte-Beitia, Juan [Departamento de Matematicas, E. T. S. de Ingenieros Industriales, Universidad de Castilla-La Mancha 13071, Ciudad Real (Spain); Perez-Garcia, Victor M. [Departamento de Matematicas, E. T. S. de Ingenieros Industriales, Universidad de Castilla-La Mancha 13071, Ciudad Real (Spain); Vekslerchik, Vadym [Departamento de Matematicas, E. T. S. de Ingenieros Industriales, Universidad de Castilla-La Mancha 13071, Ciudad Real (Spain)
2007-05-15
In this paper, we study a system of coupled nonlinear Schroedinger equations modelling a quantum degenerate mixture of bosons and fermions. We analyze the stability of plane waves, give precise conditions for the existence of solitons and write explicit solutions in the form of periodic waves. We also check that the solitons observed previously in numerical simulations of the model correspond exactly to our explicit solutions and see how plane waves destabilize to form periodic waves.
Magnetic design and modelling of a 14 mm-period prototype superconducting undulator.
Mishra, G; Gehlot, Mona; Sharma, Geetanjali; Trillaud, Frederic
2017-03-01
The magnetic design of a ten-period (each period 14 mm) prototype superconducting undulator is reported using RADIA. The results of modelling the magnetic flux density are presented in an analytical formula. The dependence of the field integrals and phase error on the current density and undulator gap has been calculated, and temperature curves are determined for the models and are compared with earlier reported Moser-Rossmanith fits.
A Predictive Model of Multi-Stage Production Planning for Fixed Time Orders
Directory of Open Access Journals (Sweden)
Kozłowski Edward
2014-09-01
Full Text Available The traditional production planning model based upon a deterministic approach is well described in the literature. Due to the uncertain nature of manufacturing processes, such model can however incorrectly represent actual situations on the shop floor. This study develops a mathematical modeling framework for generating production plans in a multistage manufacturing process. The devised model takes into account the stochastic model for predicting the occurrence of faulty products. The aim of the control model is to determine the number of products which should be manufactured in each planning period to minimize both manufacturing costs and potential financial penalties for failing to fulfill the order completely.
Modeling and analysis of biomass production systems
Energy Technology Data Exchange (ETDEWEB)
Mishoe, J.W.; Lorber, M.N.; Peart, R.M.; Fluck, R.C.; Jones, J.W.
1984-01-01
BIOMET is an interactive simulation model that is used to analyze specific biomass and methane production systems. The system model is composed of crop growth models, harvesting, transportation, conversion and economic submodels. By use of menus the users can configure the structure and set selected parameters of the system to analyze the effects of variables within the component models. For example, simulations of a water hyacinth system resulted in yields of 63, 48 and 37 mg/ha/year for different harvest schedules. For napier grass, unit methane costs were $3.04, $2.86 and $2.98 for various yields of biomass. 10 references.
Li, Jingwen; Wang, Lan; Chen, Hongzhang
2016-11-01
The acetone-butanol-ethanol (ABE) fermentation of lignocellulose at high solids content has recently attracted extensive attention. However, the productivity of high solids ABE fermentation of lignocellulose is typically low in traditional processes due to the lack of efficient intensifying methods. In the present study, periodic peristalsis, a novel intensifying method, was applied to improve ABE production by the simultaneous saccharification and fermentation (SSF) of steam-exploded corn straw using Clostridium acetobutylicum ATCC824. The ABE concentration and the ABE productivity of SSF at a solids content of 17.5% (w/w) with periodic peristalsis were 17.1 g/L and 0.20 g/(L h), respectively, which were higher than those obtained under static conditions (15.2 g/L and 0.14 g/(L h)). The initial sugar conversion rate over the first 12 h with periodic peristalsis was 4.67 g/(L h) at 10 FPU/g cellulase dosage and 15% (w/w) solids content, an increase of 49.7% compared with the static conditions. With periodic peristalsis, the period of batch fermentation was shortened from 108 h to 84 h. The optimal operating regime was a low frequency (6 h(-1)) of periodic peristalsis in the acid-production phase (0-48 h) of SSF. Therefore, periodic peristalsis should be an effective intensifying method to increase the productivity of ABE fermentation at high solids content.
Logic Model Checking of Time-Periodic Real-Time Systems
Florian, Mihai; Gamble, Ed; Holzmann, Gerard
2012-01-01
In this paper we report on the work we performed to extend the logic model checker SPIN with built-in support for the verification of periodic, real-time embedded software systems, as commonly used in aircraft, automobiles, and spacecraft. We first extended the SPIN verification algorithms to model priority based scheduling policies. Next, we added a library to support the modeling of periodic tasks. This library was used in a recent application of the SPIN model checker to verify the engine control software of an automobile, to study the feasibility of software triggers for unintended acceleration events.
Coexisting chaotic and multi-periodic dynamics in a model of cardiac alternans
Energy Technology Data Exchange (ETDEWEB)
Skardal, Per Sebastian, E-mail: skardals@gmail.com [Departament d' Enginyeria Informàtica i Matemàtiques, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Restrepo, Juan G., E-mail: juanga@colorado.edu [Department of Applied Mathematics, University of Colorado, Boulder, Colorado 80309 (United States)
2014-12-15
The spatiotemporal dynamics of cardiac tissue is an active area of research for biologists, physicists, and mathematicians. Of particular interest is the study of period-doubling bifurcations and chaos due to their link with cardiac arrhythmogenesis. In this paper, we study the spatiotemporal dynamics of a recently developed model for calcium-driven alternans in a one dimensional cable of tissue. In particular, we observe in the cable coexistence of regions with chaotic and multi-periodic dynamics over wide ranges of parameters. We study these dynamics using global and local Lyapunov exponents and spatial trajectory correlations. Interestingly, near nodes—or phase reversals—low-periodic dynamics prevail, while away from the nodes, the dynamics tend to be higher-periodic and eventually chaotic. Finally, we show that similar coexisting multi-periodic and chaotic dynamics can also be observed in a detailed ionic model.
Translation-invariant and periodic Gibbs measures for the Potts model on a Cayley tree
Khakimov, R. M.; Khaydarov, F. Kh.
2016-11-01
We study translation-invariant Gibbs measures on a Cayley tree of order k = 3 for the ferromagnetic three-state Potts model. We obtain explicit formulas for translation-invariant Gibbs measures. We also consider periodic Gibbs measures on a Cayley tree of order k for the antiferromagnetic q-state Potts model. Moreover, we improve previously obtained results: we find the exact number of periodic Gibbs measures with the period two on a Cayley tree of order k ≥ 3 that are defined on some invariant sets.
Age-period-cohort modelling of breast cancer incidence in the Nordic countries
DEFF Research Database (Denmark)
Rostgaard, K; Vaeth, M; Holst, H
2001-01-01
into account. Assuming the age dependency of the incidence pattern in old age to be common for the Nordic countries, an internal comparison could be made among the four countries of the cohort effects and the period effects. The study indicated that the period effects have been of importance for the increase......The Nordic countries have experienced a steady increase in breast cancer incidence throughout the past 35 years. We analysed the incidence in Denmark, Finland, Norway and Sweden during the period 1958 to 1992 using age-period-cohort models and taking the systematic mammography screening...... in breast cancer incidence seen in the Nordic countries. The widespread practice of neglecting the period effects in age-period-cohort analysis of time trends in breast cancer incidence therefore probably needs reconsideration. A key finding was that Danish women born in the 20th century seem to have been...
Directory of Open Access Journals (Sweden)
Jian Song
2006-01-01
conditions for the global attractivity of N*(t. Our results imply that under the appropriate periodic impulsive perturbations, the impulsive delay equation preserves the original periodic property of the nonimpulsive delay equation. In particular, our work extends and improves some known results.
The log-periodic-AR(1)-GARCH(1,1) model for financial crashes
Gazola, L; Pizzinga, A; Riera, R
2008-01-01
This paper intends to meet recent claims for the attainment of more rigorous statistical methodology within the econophysics literature. To this end, we consider an econometric approach to investigate the outcomes of the log-periodic model of price movements, which has been largely used to forecast financial crashes. In order to accomplish reliable statistical inference for unknown parameters, we incorporate an autoregressive dynamic and a conditional heteroskedasticity structure in the error term of the original model, yielding the log-periodic-AR(1)-GARCH(1,1) model. Both the original and the extended models are fitted to financial indices of U. S. market, namely S&P500 and NASDAQ. Our analysis reveal two main points: (i) the log-periodic-AR(1)-GARCH(1,1) model has residuals with better statistical properties and (ii) the estimation of the parameter concerning the time of the financial crash has been improved.
Statistical modelling of fine red wine production
María Rosa Castro; Marcelo Eduardo Echegaray; Rosa Ana Rodríguez; Stella Maris Udaquiola
2010-01-01
Producing wine is a very important economic activity in the province of San Juan in Argentina; it is therefore most important to predict production regarding the quantity of raw material needed. This work was aimed at obtaining a model relating kilograms of crushed grape to the litres of wine so produced. Such model will be used for predicting precise future values and confidence intervals for determined quantities of crushed grapes. Data from a vineyard in the province of San Juan was ...
Institute of Scientific and Technical Information of China (English)
Shixiong; ZHU
2015-01-01
In recent years,Guangxi realized consecutive bumper harvests in fresh agricultural products,leading increase of logistics demand;logistics infrastructure begins to take shape,and logistics of fresh agricultural products takes on diversified development form with wholesale market as main form. However,traditional fresh agricultural products are not selling well and it lacks construction of supply chain; the construction of logistics information system for fresh agricultural products lags behind; organizational level of production and operation of fresh agricultural products is low. Through analyzing current situations and existing problems of logistics of Guangxi fresh agricultural products in the new period( 21 st century),this paper came up with recommendations for developing logistics of fresh agricultural products of Guangxi. Government should increase policy and financial support,build and manage supply chain of fresh agricultural products,accelerate construction of logistics information system for agricultural products,and improve organizational level of logistics of fresh agricultural products,to ensure healthy development of logistics of fresh agricultural products in Guangxi.
Energy Technology Data Exchange (ETDEWEB)
Skolski, J. Z. P., E-mail: j.z.p.skolski@utwente.nl; Vincenc Obona, J. [Materials innovation institute M2i, Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Römer, G. R. B. E.; Huis in ' t Veld, A. J. [Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)
2014-03-14
A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by “ablation after each laser pulse,” according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to “grow” either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelength of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.
Skolski, J. Z. P.; Römer, G. R. B. E.; Vincenc Obona, J.; Huis in't Veld, A. J.
2014-03-01
A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by "ablation after each laser pulse," according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to "grow" either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelength of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.
A modified Lee-Carter model for analysing short-base-period data.
Zhao, Bojuan Barbara
2012-03-01
This paper introduces a new modified Lee-Carter model for analysing short-base-period mortality data, for which the original Lee-Carter model produces severely fluctuating predicted age-specific mortality. Approximating the unknown parameters in the modified model by linearized cubic splines and other additive functions, the model can be simplified into a logistic regression when fitted to binomial data. The expected death rate estimated from the modified model is smooth, not only over ages but also over years. The analysis of mortality data in China (2000-08) demonstrates the advantages of the new model over existing models.
Modeling UK Natural Gas Prices when Gas Prices Periodically Decouple from the Oil Price
2015-01-01
When natural gas prices are subject to periodic decoupling from oil prices, for instance due to peak-load pricing, conventional linear models of price dynamics such as the Vector Error Correction Model (VECM) can lead to erroneous inferences about cointegration relationships, price adjustments and relative values. We propose the use of regime-switching models to address these issues. Our regime switching model uses price data to infer whether pricing is oil-driven (integrated) or gas-specific...
Design, product structuring and modelling of mechatronic products and systems
DEFF Research Database (Denmark)
Conrad, Finn; Sørensen, Torben
2003-01-01
Information Technology offers software and hardware for improvement of the engineering design, structuring and control systems, and industrial applications. The latest progress in IT makes integration of an overall design and manufacturing IT- concept feasible and commercially attractive. An IT......-tool concept for modelling, simulation and design of mechatronic products and systems is proposed in this paper. It built on results from a Danish mechatronic research program on intelligent motion control as well as from the Esprit project SWING on IT-tools for rapid prototyping of fluid power components...
Design, product structuring and modelling of mechatronic products and systems
DEFF Research Database (Denmark)
Conrad, Finn; Sørensen, Torben
2003-01-01
Information Technology offers software and hardware for improvement of the engineering design, structuring and control systems, and industrial applications. The latest progress in IT makes integration of an overall design and manufacturing IT- concept feasible and commercially attractive. An IT......-tool concept for modelling, simulation and design of mechatronic products and systems is proposed in this paper. It built on results from a Danish mechatronic research program on intelligent motion control as well as from the Esprit project SWING on IT-tools for rapid prototyping of fluid power components...
Lopez, Jose R; Kolster, Juan; Zhang, Rui; Adams, Jose
2017-07-01
Duchenne Muscular Dystrophy (DMD) cardiomyopathy is a progressive lethal disease caused by the lack of the dystrophin protein in the heart. The most widely used animal model of DMD is the dystrophin-deficient mdx mouse; however, these mice exhibit a mild dystrophic phenotype with heart failure only late in life. In contrast, mice deficient for both dystrophin and utrophin (mdx/utrn(-/-), or dKO) can be used to model severe DMD cardiomyopathy where pathophysiological indicators of heart failure are detectable by 8-10weeks of age. Nitric oxide (NO) is an important signaling molecule involved in vital functions of regulating rhythm, contractility, and microcirculation of the heart, and constitutive NO production affects the function of proteins involved in excitation-contraction coupling. In this study, we explored the efficacy of enhancing NO production as a therapeutic strategy for treating DMD cardiomyopathy using the dKO mouse model of DMD. Specifically, NO production was induced via whole body periodic acceleration (pGz), a novel non-pharmacologic intervention which enhances NO synthase (NOS) activity through sinusoidal motion of the body in a headward-footward direction, introducing pulsatile shear stress to the vascular endothelium and cardiomyocyte plasma membrane. Male dKO mice were randomized at 8weeks of age to receive daily pGz (480cpm, Gz±3.0m/s(2), 1h/d) for 4weeks or no treatment, and a separate age-matched group of WT animals (pGz-treated and untreated) served as non-diseased controls. At the conclusion of the protocol, cardiomyocytes from untreated dKO animals had, respectively, 4.3-fold and 3.5-fold higher diastolic resting concentration of Ca(2+) ([Ca(2+)]d) and Na(+) ([Na(+)]d) compared to WT, while pGz treatment significantly reduced these levels. For dKO cardiomyocytes, pGz treatment also improved the depressed contractile function, decreased oxidative stress, blunted the elevation in calpain activity, and mitigated the abnormal increase in [Ca
Product modelling: '20 years of stalemate'?
DEFF Research Database (Denmark)
Galle, Per
1998-01-01
In a recent special issue of Design Studies Michael Ramscar, John Lee, and Helen Pain level a severe criticism against a field of research known as product modeling; a criticism that would be rather damaging if it were based on cogent arguments. I shall argue in this paper that it is not....
Applications products of aviation forecast models
Garthner, John P.
1988-01-01
A service called the Optimum Path Aircraft Routing System (OPARS) supplies products based on output data from the Naval Oceanographic Global Atmospheric Prediction System (NOGAPS), a model run on a Cyber-205 computer. Temperatures and winds are extracted from the surface to 100 mb, approximately 55,000 ft. Forecast winds are available in six-hour time steps.
Pebble Bed Reactor Dust Production Model
Energy Technology Data Exchange (ETDEWEB)
Abderrafi M. Ougouag; Joshua J. Cogliati
2008-09-01
The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.
Directory of Open Access Journals (Sweden)
Falagas Matthew E
2006-03-01
Full Text Available Abstract Background The objective of this study was to estimate the research productivity of different world regions in the field of Parasitology. Methods Using the PubMed database we retrieved articles from journals included in the "Parasitology" category of the "Journal Citation Reports" database of the Institute for Scientific Information for the period 1995–2003. Research productivity was evaluated based on a methodology we developed and used in other bibliometric studies by analysing: (1 the total number of publications, (2 the mean impact factor of all papers, and (3 the product of the above two parameters, (4 the research productivity in relation to gross domestic product of each region, and (5 the research productivity in relation to gross national income per capita and population of each region. Results Data on the country of origin of the research was available for 18,110 out of 18,377 articles (98.6% of all articles from the included journals. Western Europe exceeds all world regions in research production for the period studied (34.8% of total articles, with USA ranking second (19.9%, and Latin America & the Caribbean ranking third (17.2%. The mean impact factor in articles published in Parasitology journals was highest for the USA (1.88. Oceania ranked first in research productivity when adjustments for both the gross national income per capita (GNIPC and population were made. Eastern Europe almost tripled the production of articles from only 1.9% of total production in 1995 to 4.3% in 2003. Similarly, Latin America and the Caribbean and Asia doubled their production. However, the absolute and relative production by some developing areas, including Africa, is still very low, despite the fact that parasitic diseases are major public health problems in these areas. Conclusion Our data suggest that more help should be provided by the developed nations to developing areas for improvement of the infrastructure of research.
Directory of Open Access Journals (Sweden)
Nishiura Hiroshi
2007-05-01
Full Text Available Abstract The incubation period of infectious diseases, the time from infection with a microorganism to onset of disease, is directly relevant to prevention and control. Since explicit models of the incubation period enhance our understanding of the spread of disease, previous classic studies were revisited, focusing on the modeling methods employed and paying particular attention to relatively unknown historical efforts. The earliest study on the incubation period of pandemic influenza was published in 1919, providing estimates of the incubation period of Spanish flu using the daily incidence on ships departing from several ports in Australia. Although the study explicitly dealt with an unknown time of exposure, the assumed periods of exposure, which had an equal probability of infection, were too long, and thus, likely resulted in slight underestimates of the incubation period. After the suggestion that the incubation period follows lognormal distribution, Japanese epidemiologists extended this assumption to estimates of the time of exposure during a point source outbreak. Although the reason why the incubation period of acute infectious diseases tends to reveal a right-skewed distribution has been explored several times, the validity of the lognormal assumption is yet to be fully clarified. At present, various different distributions are assumed, and the lack of validity in assuming lognormal distribution is particularly apparent in the case of slowly progressing diseases. The present paper indicates that (1 analysis using well-defined short periods of exposure with appropriate statistical methods is critical when the exact time of exposure is unknown, and (2 when assuming a specific distribution for the incubation period, comparisons using different distributions are needed in addition to estimations using different datasets, analyses of the determinants of incubation period, and an understanding of the underlying disease mechanisms.
Energy Technology Data Exchange (ETDEWEB)
Egging, R.G.
2010-11-15
This dissertation develops deterministic and stochastic multi-period mixed complementarity problems (MCP) for the global natural gas market, as well as solution approaches for large-scale stochastic MCP. The deterministic model is unique in the combination of the level of detail of the actors in the natural gas markets and the transport options, the detailed regional and global coverage, the multi-period approach with endogenous capacity expansions for transportation and storage infrastructure, the seasonal variation in demand and the representation of market power according to Nash-Cournot theory. The model is applied to several scenarios for the natural gas market that cover the formation of a cartel by the members of the Gas Exporting Countries Forum, a low availability of unconventional gas in the United States, and cost reductions in long-distance gas transportation. The results provide insights in how different regions are affected by various developments, in terms of production, consumption, traded volumes, prices and profits of market participants. The stochastic MCP is developed and applied to a global natural gas market problem with four scenarios for a time horizon until 2050 with nineteen regions and containing 78,768 variables. The scenarios vary in the possibility of a gas market cartel formation and varying depletion rates of gas reserves in the major gas importing regions. Outcomes for hedging decisions of market participants show some significant shifts in the timing and location of infrastructure investments, thereby affecting local market situations. A first application of Benders decomposition (BD) is presented to solve a large-scale stochastic MCP for the global gas market with many hundreds of first-stage capacity expansion variables and market players exerting various levels of market power. The largest problem solved successfully using BD contained 47,373 variables of which 763 first-stage variables, however using BD did not result in
Multi-period natural gas market modeling Applications, stochastic extensions and solution approaches
Egging, Rudolf Gerardus
This dissertation develops deterministic and stochastic multi-period mixed complementarity problems (MCP) for the global natural gas market, as well as solution approaches for large-scale stochastic MCP. The deterministic model is unique in the combination of the level of detail of the actors in the natural gas markets and the transport options, the detailed regional and global coverage, the multi-period approach with endogenous capacity expansions for transportation and storage infrastructure, the seasonal variation in demand and the representation of market power according to Nash-Cournot theory. The model is applied to several scenarios for the natural gas market that cover the formation of a cartel by the members of the Gas Exporting Countries Forum, a low availability of unconventional gas in the United States, and cost reductions in long-distance gas transportation. 1 The results provide insights in how different regions are affected by various developments, in terms of production, consumption, traded volumes, prices and profits of market participants. The stochastic MCP is developed and applied to a global natural gas market problem with four scenarios for a time horizon until 2050 with nineteen regions and containing 78,768 variables. The scenarios vary in the possibility of a gas market cartel formation and varying depletion rates of gas reserves in the major gas importing regions. Outcomes for hedging decisions of market participants show some significant shifts in the timing and location of infrastructure investments, thereby affecting local market situations. A first application of Benders decomposition (BD) is presented to solve a large-scale stochastic MCP for the global gas market with many hundreds of first-stage capacity expansion variables and market players exerting various levels of market power. The largest problem solved successfully using BD contained 47,373 variables of which 763 first-stage variables, however using BD did not result in
Ulrich, Rolf; Miller, Jeff
2008-01-01
Response grouping is a ubiquitous phenomenon in psychological refractory period (PRP) tasks, yet it hampers the analysis of dual-task performance. To account for response grouping, we developed several extended versions of the standard bottleneck model, each of which incorporates a possible grouping mechanism into this model. Computer simulations…
Rich dynamics in a predator–prey model with both noise and periodic force
Sun, G.Q.; Jin, Z.; Liu, Q.X.; Li, B.L.
2010-01-01
A spatial version of the predator–prey model with Holling III functional response, which includes some important factors such as external periodic forces, noise, and diffusion processes is investigated. For the model only with diffusion, it exhibits spiral waves in the two-dimensional space. However
Directory of Open Access Journals (Sweden)
S. S. Mishra
2008-01-01
Full Text Available A probabilistic inventory model for conditional credit period with exponential demand, non-zero lead time and multiple storage facility has been developed. The behaviour of total expected cost (TEC has been examined and the use and application of the model is demonstrated with the help of a numerical example.
Spreading Speed for a Periodic Reaction-diffusion Model with Nonmonotone Birth Function
Institute of Scientific and Technical Information of China (English)
HUANG Ye-hui; WENG Pei-xuan
2012-01-01
A reaction-diffusion model for a single spccies with age structure and nonlocal reaction for periodic time t is derived.Some results about the model with monotone birth function are firstly introduced,and then by constructing two auxiliary equations and squeezing method,the spreading speed for the system with nonmonotone birth function is obtained.
A Time-Delayed Mathematical Model for Tumor Growth with the Effect of a Periodic Therapy
Directory of Open Access Journals (Sweden)
Shihe Xu
2016-01-01
Full Text Available A time-delayed mathematical model for tumor growth with the effect of periodic therapy is studied. The establishment of the model is based on the reaction-diffusion dynamics and mass conservation law and is considered with a time delay in cell proliferation process. Sufficient conditions for the global stability of tumor free equilibrium are given. We also prove that if external concentration of nutrients is large the tumor will not disappear and the conditions under which there exist periodic solutions to the model are also determined. Results are illustrated by computer simulations.
On periodic solutions of Goodwin's business cycle model with only floor in induced investment
Antonova, A. O.; Reznik, S. N.; Todorov, M. D.
2013-10-01
We present here an analytical solution of Goodwin's business cycle model in the form of delay differential equation with fixed delay θ and piecewise linear accelerator with only the floor (or the ceiling). We conclude that in this model the time behavior of the solution similar to Goodwin's limit cycle is not possible. These solution looks similar to the oscillation with a period θ, the amplitude of the oscillation growing exponentially to infinity as t →∞. The conditions for existence of the periodic solution in Goodwin's model with fixed delay for the nonlinear accelerator are also discussed.
Self-similarities of periodic structures for a discrete model of a two-gene system
Energy Technology Data Exchange (ETDEWEB)
Souza, S.L.T. de, E-mail: thomaz@ufsj.edu.br [Departamento de Física e Matemática, Universidade Federal de São João del-Rei, Ouro Branco, MG (Brazil); Lima, A.A. [Escola de Farmácia, Universidade Federal de Ouro Preto, Ouro Preto, MG (Brazil); Caldas, I.L. [Instituto de Física, Universidade de São Paulo, São Paulo, SP (Brazil); Medrano-T, R.O. [Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo, Diadema, SP (Brazil); Guimarães-Filho, Z.O. [Aix-Marseille Univ., CNRS PIIM UMR6633, International Institute for Fusion Science, Marseille (France)
2012-03-12
We report self-similar properties of periodic structures remarkably organized in the two-parameter space for a two-gene system, described by two-dimensional symmetric map. The map consists of difference equations derived from the chemical reactions for gene expression and regulation. We characterize the system by using Lyapunov exponents and isoperiodic diagrams identifying periodic windows, denominated Arnold tongues and shrimp-shaped structures. Period-adding sequences are observed for both periodic windows. We also identify Fibonacci-type series and Golden ratio for Arnold tongues, and period multiple-of-three windows for shrimps. -- Highlights: ► The existence of noticeable periodic windows has been reported recently for several nonlinear systems. ► The periodic window distributions appear highly organized in two-parameter space. ► We characterize self-similar properties of Arnold tongues and shrimps for a two-gene model. ► We determine the period of the Arnold tongues recognizing a Fibonacci-type sequence. ► We explore self-similar features of the shrimps identifying multiple period-three structures.
Dynamics and Complexity in a Time Delay Model of RNA Silencing with Periodic Forcing
Directory of Open Access Journals (Sweden)
Svetoslav Nikolov
2008-10-01
Full Text Available Simple periodic behavior and occurrence of complex oscillatory phenomena underlie of a large number of biochemical system models. In many cases the transition from stable to simple/complex oscillatory behavior can be connected with the appearance of abnormal process likes as cancer. In this paper we propose a time delay model of RNA silencing (also known as RNA interference with periodic forcing. In organisms with RNA silencing, each cell has a miniature "immune system" able to generate and amplify specific responses to a variety of gene transcripts. The consequences of a time delay on the dynamics of this model are analysed using Hopf's theorem. Our analytical calculations predict that time delay acts as a key bifurcation parameter. From the accomplished numerical results, it becomes clear that model has complexity oscillatory behavior when the amplitude of periodic force (i.e. the confusion in the target mRNA synthesis is large.
Awati, A.; Urso, D' S.; Williams, B.A.; Bosch, M.; Verstegen, M.W.A.
2007-01-01
Pre-weaning development of microbial activity has an effect on post-weaning establishment of the gastro-intestinal tract (GIT) microbiota. An in vivo study was conducted, to evaluate the effect of age on fermentation end-product profiles during the post-colostrum suckling period, as the variation in
Ergot alkaloids in endophyte-infected grasses inhibit prolactin (PRL) secretion and may reduce milk production of cows consuming endophyte-infected grasses. We investigated the effects of consuming endophyte-infected fescue during late lactation and the dry period on mammary growth, differentiation ...
National Research Council Canada - National Science Library
Avendaño-Reyes, L; Alvarez-Valenzuela, F. D; Correa-Calderón, A; Fadel, J. G; Robinson, P. H
2008-01-01
Avendaño-Reyes, L., Alvarez-Valenzuela, F.D., Correa-Calderón, A., Fadel, J.G. and Robinson, P.H. 2008. Is soaking cows during dry period an effective management tool to reduce heat stress and improve pospartum productivity...
Decision models in designing flexible production systems
Directory of Open Access Journals (Sweden)
Florescu Adriana
2017-01-01
Full Text Available Flexible production system is a complex whole that raise some issues in terms of its design and in relation to the conditions for implementing it. To implement a flexible production system configuration must be found that satisfies both economic and system performance requirements. The configuration which best meet the objectives of introducing a flexible production system must be sought in the set of alternatives defined and evaluated. In this paper we present a methodology of realising the configuration and complex evaluation of the analyzed system. It will be developed models which generate new alternative configurations, optimization and evaluation models of the performance of the flexible production system. This will create a framework for interactive decision support, user-oriented that can be used by management to solve this selection problem. The applicative character of the study consist in tracking of the technological process in real time using the developed software package on the designed system, based on mathematical models for configuration and optimization of the system.
Directory of Open Access Journals (Sweden)
K. Skouri
2009-01-01
Full Text Available An order level inventory model for seasonable/fashionable products subject to a period of increasing demand followed by a period of level demand and then by a period of decreasing demand rate (three branches ramp type demand rate is considered. The unsatisfied demand is partially backlogged with a time dependent backlogging rate. In addition, the product deteriorates with a time dependent, namely, Weibull, deterioration rate. The model is studied under the following different replenishment policies: (a starting with no shortages and (b starting with shortages. The optimal replenishment policy for the model is derived for both the above mentioned policies.
Determination of the periodicity and synchronization of anticipative agent based supply-demand model
Škraba, A.; Bren, M.; Kofjač, D.
2017-02-01
The paper presents the transformation of cobweb model by including the anticipation about the supply and demand. Developed transformation leads to oscillatory behaviour. The periodic conditions of the model have been analytically determined by the application of z-transform. Periodic solutions of the system are presented in the form of an inverse Farey tree, where the Golden Ratio path could be observed. The table of periodic conditions is given up to period 8. The agent-based system was developed in order to show the possibility of controlling the system by varying the key parameter, which determines the frequency response of agents and their interaction. A note on application in the stock market has been provided.
Modelling the ATP production in mitochondria
Saa, Alberto
2012-01-01
We revisit here the mathematical model for ATP production in mitochondria introduced recently by Bertram, Pedersen, Luciani, and Sherman (BPLS) as a simplification of the more complete but intricate Magnus and Keizer's model. We correct some inaccuracies in the BPLS original approximations and then analyze some of the dynamical properties of the model. We infer from exhaustive numerical explorations that the enhanced BPLS equations have a unique attractor fixed point for physiologically acceptable ranges of mitochondrial variables and respiration inputs. We determine, in the stationary regime, the dependence of the mitochondrial variables on the respiration inputs, namely the cytosolic concentration of calcium ${\\rm Ca}_{\\rm c}$ and the substrate fructose 1,6-bisphosphate FBP. The same effect of calcium saturation reported for the original BPLS model is observed here. We find out, however, an interesting non-stationary effect: the inertia of the model tends to increase considerably for high concentrations of ...
Surovyatkina, Elena; Egorchenkov, Roman; Ivanov, Guennady
2007-06-01
The coexistence of different dynamical regimes of cardiac cell-model at a fixed set of stimulation parameters, i.e. multistability, revealed by noise is presented in this paper. Numerical simulations are performed using Luo-Rudy (LR1) action potential model. Numerical experiments with LR1 model conducted via noisy periodical stimulation showed the coexistence of several periodic rhythms. Weak noise in period of stimulation causes a hopping process between all the (meta-) stable rhythms of cell-model. This process is reflected in several parallel branches of the bifurcation diagram: noise unveils new, invisible before, stable rhythms which could appear in this model at different initial conditions. The phenomenon of multistability is directly evidenced by other numerical experiments: we have established the multistability property of a cell consisting in the fact that different initial conditions of stimulation (different extrasystole application times) lead to different stable periodic rhythms. We have obtained the shaping of attraction basins on the action potential curves. Such basins of attraction contain a set of initial conditions which determinate a stable periodic rhythm. We have found a close association between the attraction basins of the complex rhythms on the curves of action potential and the cardiac vulnerable windows on ECG record, during which extra stimuli can induce life threatening arrhythmias. Obtained results allow us to make a conclusion that multistability is very important for the electrical conduction system of the heart from the cell level to the integrated function of the heart.
EVALUATION OF MANUFACTURING AND AGRICULTURAL PRODUCTION BY THE END OF THE FINANCIAL PERIOD
Directory of Open Access Journals (Sweden)
Mincho Minev
2016-06-01
Full Text Available This article is dedicated on the matter of evaluation of manufacturing and agricultural production after the initial appraisal. Accounting standards and regulations, concerning the reappraisal of production, are discussed with emphasis on the key and most disputable requirements. The most commonly met difficulties in the process of reappraisal of production are pointed out. A research is done over the leading manufacturing and agricultural entities in Bulgaria. The point of the research is to study the degree on witch entities met the requirements and regulations of accounting standards when they reevaluate their production by the end of the year. The results of the research are shown and analyzed. Conclusions are made along with some recommendations in order to improve the quality of reappraisal of manufacturing and agricultural production.
Streamlining environmental product declarations: a stage model
Lefebvre, Elisabeth; Lefebvre, Louis A.; Talbot, Stephane; Le Hen, Gael
2001-02-01
General public environmental awareness and education is increasing, therefore stimulating the demand for reliable, objective and comparable information about products' environmental performances. The recently published standard series ISO 14040 and ISO 14025 are normalizing the preparation of Environmental Product Declarations (EPDs) containing comprehensive information relevant to a product's environmental impact during its life cycle. So far, only a few environmentally leading manufacturing organizations have experimented the preparation of EPDs (mostly from Europe), demonstrating its great potential as a marketing weapon. However the preparation of EPDs is a complex process, requiring collection and analysis of massive amounts of information coming from disparate sources (suppliers, sub-contractors, etc.). In a foreseeable future, the streamlining of the EPD preparation process will require product manufacturers to adapt their information systems (ERP, MES, SCADA) in order to make them capable of gathering, and transmitting the appropriate environmental information. It also requires strong functional integration all along the product supply chain in order to ensure that all the information is made available in a standardized and timely manner. The goal of the present paper is two fold: first to propose a transitional model towards green supply chain management and EPD preparation; second to identify key technologies and methodologies allowing to streamline the EPD process and subsequently the transition toward sustainable product development
Bent, Henry A.; Weinhold, Frank
2007-01-01
The study presents and explains the various periodicity symbols, tables and models for the higher-order valency and donor-acceptor kinships used in chemistry. The described alternative tables are expected to improve the pedagogical consistency of the chemical periodicity patterns with better electronic behavior.
Bent, Henry A.; Weinhold, Frank
2007-01-01
The study presents and explains the various periodicity symbols, tables and models for the higher-order valency and donor-acceptor kinships used in chemistry. The described alternative tables are expected to improve the pedagogical consistency of the chemical periodicity patterns with better electronic behavior.
Institute of Scientific and Technical Information of China (English)
HU Zifeng; TAN Yehui; SONG Xingyu; ZHOU Linbin; LIAN Xiping; HUANG Liangmin; HE Yinghui
2014-01-01
Mesoscale eddies have been suggested to have an impact on biological carbon fixation in the South China Sea (SCS). However, their overall contribution to primary production during the spring inter-monsoon pe-riod is still unknown. Based on large-scale biological and environmental in situ observations and synchro-nous remote sensing data, the distribution patterns of phytoplankton biomass and the primary production, and the role of mesoscale eddies in regulating primary production in different eddy-controlled waters were investigated. The results suggested that the surface chlorophyll a concentrations and water column inte-grated primary production (IPP) are significantly higher in cyclonic eddies and lower in the anticyclonic eddies as compared to that in non-eddy waters. Although eddies could affect various environmental factors, such as nutrients, temperature and light availability, nutrient supply is suggested to be the most important one through which mesoscale eddies regulated the distribution patterns of phytoplankton biomass and pri-mary production. The estimated IPP in cyclonic and anticyclonic eddies are about 29.5%higher and 16.6%lower than the total average in the whole study area, respectively, indicating that the promotion effect of mesoscale cold eddies on the primary production was much stronger than the inhibition effect of the warm eddies per unit area. Overall, mesoscale eddies are crucial physical processes that affect the biological car-bon fixation and the distribution pattern of primary production in the SCS open sea, especially during the spring inter-monsoon period.
Directory of Open Access Journals (Sweden)
CC Pizzolante
2006-09-01
Full Text Available Three experiments were carried out to analyze the performance and egg quality of Japanese quails throughout the day when submitted to different lighting programs. In each experiment, birds were submitted to a period of 28 days for adaptation to the lighting program. During the following three days, each day - from 7 am to 7 pm or 9 pm - was divided into six or seven periods of two hours each, and the remaining hours corresponded to another single period. All birds were submitted to the same management practices, and received water and feed ad libitum. The experimental diet was formulated according to NRC (1994 standards. It was observed lower feed intake in the period of 9 pm to 7 am, and a higher incidence of lay from 3 pm to 7 pm, as opposite to hens, which peak of egg laying occurs during the morning. Some controversial results were found among experiments as to eggshell quality during the different periods of the day. Variation on the lighting program had little influence on the other performance and egg quality parameters.
Model atmospheres with periodic shocks. [pulsations and mass loss in variable stars
Bowen, G. H.
1989-01-01
The pulsation of a long-period variable star generates shock waves which dramatically affect the structure of the star's atmosphere and produce conditions that lead to rapid mass loss. Numerical modeling of atmospheres with periodic shocks is being pursued to study the processes involved and the evolutionary consequences for the stars. It is characteristic of these complex dynamical systems that most effects result from the interaction of various time-dependent processes.
Positive Almost Periodic Solution on a Nonlinear Logistic Biological Model with Grazing Rates
Institute of Scientific and Technical Information of China (English)
NI Hua; TIAN Li-xin
2013-01-01
In this paper,we study the following nonlinear biological model dx(t)/dt =x(t)[a(t)-b(t)xα(t)] + f(t,xt),by using fixed pointed theorem,the sufficient conditions of the existence of unique positive almost periodic solution for the above system are obtained,by using the theories of stability,the sufficient conditions which guarantee the stability of the positive almost periodic solution are derived.
ARTICLES: Thermohydrodynamic models of the interaction of pulse-periodic radiation with matter
Arutyunyan, R. V.; Baranov, V. Yu; Bol'shov, Leonid A.; Malyuta, D. D.; Mezhevov, V. S.; Pis'mennyĭ, V. D.
1987-02-01
Experimental and theoretical investigations were made of the processes of drilling and deep melting of metals by pulsed and pulse-periodic laser radiation. Direct photography of the surface revealed molten metal splashing due to interaction with single CO2 laser pulses. A proposed thermohydrodynamic model was used to account for the experimental results and to calculate the optimal parameters of pulse-periodic radiation needed for deep melting. The melt splashing processes were simulated numerically.
Model atmospheres with periodic shocks. [pulsations and mass loss in variable stars
Bowen, G. H.
1989-01-01
The pulsation of a long-period variable star generates shock waves which dramatically affect the structure of the star's atmosphere and produce conditions that lead to rapid mass loss. Numerical modeling of atmospheres with periodic shocks is being pursued to study the processes involved and the evolutionary consequences for the stars. It is characteristic of these complex dynamical systems that most effects result from the interaction of various time-dependent processes.
Impact of the calibration period on the conceptual rainfall-runoff model parameter estimates
Todorovic, Andrijana; Plavsic, Jasna
2015-04-01
A conceptual rainfall-runoff model is defined by its structure and parameters, which are commonly inferred through model calibration. Parameter estimates depend on objective function(s), optimisation method, and calibration period. Model calibration over different periods may result in dissimilar parameter estimates, while model efficiency decreases outside calibration period. Problem of model (parameter) transferability, which conditions reliability of hydrologic simulations, has been investigated for decades. In this paper, dependence of the parameter estimates and model performance on calibration period is analysed. The main question that is addressed is: are there any changes in optimised parameters and model efficiency that can be linked to the changes in hydrologic or meteorological variables (flow, precipitation and temperature)? Conceptual, semi-distributed HBV-light model is calibrated over five-year periods shifted by a year (sliding time windows). Length of the calibration periods is selected to enable identification of all parameters. One water year of model warm-up precedes every simulation, which starts with the beginning of a water year. The model is calibrated using the built-in GAP optimisation algorithm. The objective function used for calibration is composed of Nash-Sutcliffe coefficient for flows and logarithms of flows, and volumetric error, all of which participate in the composite objective function with approximately equal weights. Same prior parameter ranges are used in all simulations. The model is calibrated against flows observed at the Slovac stream gauge on the Kolubara River in Serbia (records from 1954 to 2013). There are no trends in precipitation nor in flows, however, there is a statistically significant increasing trend in temperatures at this catchment. Parameter variability across the calibration periods is quantified in terms of standard deviations of normalised parameters, enabling detection of the most variable parameters
Modeling of continuous strip production by rheocasting
Matsumiya, T.; Flemings, M. C.
1981-03-01
A process was experimentally and mathematically modeled for continuous and direct production of metal strip from its molten state by the use of Rheocasting. The process comprises 1) continuous production of a Rheocast semisolid alloy, and 2) direct shaping of the semisolid into strip. Sn-15 pct Pb was used as the modeling alloy. Crack formation and surface quality of the strip produced depend on fraction solid and deformation force. Continuous, sound strip could be obtained with good surface quality when fraction solid was between 0.50 and 0.70 and deformation force did not exceed a given maximum. Sheet thickness depends on deformation force, fraction solid, rotor rate of Rheocaster and production line speed. At constant deformation force, sheet thickness increases as fraction solid increases, rotor rate decreases and line speed is reduced. Sheet thickness is larger in the center than in the edge, but the difference is reduced by applying edgers. Some segregation of lead toward the edges is observed, and the segregation increases as amount of deformation is increased. A mathematical model for heat flow, solidification and deformation was constructed. The model predicts the point of completion of solidification in the strip and sheet thickness as a function of deformation force and line speed. Calculations are in good agreement with experimental results.
Modeling of continuous strip production by rheocasting
Energy Technology Data Exchange (ETDEWEB)
Matsumiya, T.; Flemings, M.C.
1981-03-01
A process was experimentally and mathematically modeled for continuous and direct production of metal strip from its molten state by the use of Rheocasting. The process comprises 1) continuous production of a Rheocast semisolid alloy, and 2) direct shaping of the semisolid into strip. Sn-15 pct Pb was used as the modeling alloy. Crack formation and surface quality of the strip produced depend on fraction solid and deformation force. Continuous, sound strip could be obtained with good surface quality when fraction solid was between 0.50 and 0.70 and deformation force did not exceed a given maximum. Sheet thickness depends on deformation force, fraction solid, rotor rate of Rheocaster and production line speed. At constant deformation force, sheet thickness increases as fraction solid increases, rotor rate decreases and line speed is reduced. Sheet thickness is larger in the center than in the edge, but the difference is reduced by applying edgers. Some segregation of lead toward the edges is observed, ad the segregation increases as amount of deformation is increased. A mathematical model for heat flow, solidification and deformation was constructed. The model predicts the point of completion of solidification in the strip and sheet thickness as a function of deformation force and line speed. Calculations are in good agreement with experimental results.
Up-to-date and precise estimates of cancer patient survival: model-based period analysis.
Brenner, Hermann; Hakulinen, Timo
2006-10-01
Monitoring of progress in cancer patient survival by cancer registries should be as up-to-date as possible. Period analysis has been shown to provide more up-to-date survival estimates than do traditional methods of survival analysis. However, there is a trade-off between up-to-dateness and the precision of period estimates, in that increasing the up-to-dateness of survival estimates by restricting the analysis to a relatively short, recent time period, such as the most recent calendar year for which cancer registry data are available, goes along with a loss of precision. The authors propose a model-based approach to maximize the up-to-dateness of period estimates at minimal loss of precision. The approach is illustrated for monitoring of 5-year relative survival of patients diagnosed with one of 20 common forms of cancer in Finland between 1953 and 2002 by use of data from the nationwide Finnish Cancer Registry. It is shown that the model-based approach provides survival estimates that are as up-to-date as the most up-to-date conventional period estimates and at the same time much more precise than the latter. The modeling approach may further enhance the use of period analysis for deriving up-to-date cancer survival rates.
Periodic Properties of 1D FE Discrete Models in High Frequency Dynamics
Directory of Open Access Journals (Sweden)
A. Żak
2016-01-01
Full Text Available Finite element discrete models of various engineering 1D structures may be considered as structures of certain periodic characteristics. The source of this periodicity comes from the discontinuity of stress/strain field between the elements. This behaviour remains unnoticeable, when low frequency dynamics of these structures is investigated. At high frequency regimes, however, its influence may be strong enough to dominate calculated structural responses distorting or even falsifying them completely. In this paper, certain computational aspects of structural periodicity of 1D FE discrete models are discussed by the authors. In this discussion, the authors focus their attention on an exemplary problem of 1D rod modelled according to the elementary theory.
Model of the Product Development Lifecycle.
Energy Technology Data Exchange (ETDEWEB)
He, Sunny L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Roe, Natalie H. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wood, Evan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nachtigal, Noel M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Helms, Jovana [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-10-01
While the increased use of Commercial Off-The-Shelf information technology equipment has presented opportunities for improved cost effectiveness and flexibility, the corresponding loss of control over the product's development creates unique vulnerabilities and security concerns. Of particular interest is the possibility of a supply chain attack. A comprehensive model for the lifecycle of hardware and software products is proposed based on a survey of existing literature from academic, government, and industry sources. Seven major lifecycle stages are identified and defined: (1) Requirements, (2) Design, (3) Manufacturing for hardware and Development for software, (4) Testing, (5) Distribution, (6) Use and Maintenance, and (7) Disposal. The model is then applied to examine the risk of attacks at various stages of the lifecycle.
Xu, Jian Z; Zhang, Jun L; Hu, Kai H; Zhang, Wei G
2013-05-01
Mushrooms are able to secrete lignin peroxidase (LiP) and manganese peroxidase (MnP), and able to use the cellulose as sources of carbon. This article focuses on the relation between peroxidase-secreting capacity and cultivation period of mushrooms with non-laccase activity. Methylene blue and methyl catechol qualitative assay and spectrophotometry quantitative assay show LiP secreting unvaryingly accompanies the MnP secreting in mushroom strains. The growth rates of hyphae are detected by detecting the dry hyphal mass. We link the peroxidase activities to growth rate of mushrooms and then probe into the relationship between them. The results show that there are close relationships between LiP- and/or MnP-secretory capacities and the cultivation periods of mushrooms. The strains with high LiP and MnP activities have short cultivation periods. However, those strains have long cultivation periods because of the low levels of secreted LiP and/or MnP, even no detectable LiP and/or MnP activity. This study provides the first evidence on the imitate relation between the level of secreted LiP and MnP activities and cultivation periods of mushrooms with non-laccase activity. Our study has significantly increased the understanding of the role of LiP and MnP in the growth and development of mushrooms with non-laccase activity. © 2012 The Authors. Microbial Biotechnology © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.
On the discretization and control of an SEIR epidemic model with a periodic impulsive vaccination
Alonso-Quesada, S.; De la Sen, M.; Ibeas, A.
2017-01-01
This paper deals with the discretization and control of an SEIR epidemic model. Such a model describes the transmission of an infectious disease among a time-varying host population. The model assumes mortality from causes related to the disease. Our study proposes a discretization method including a free-design parameter to be adjusted for guaranteeing the positivity of the resulting discrete-time model. Such a method provides a discrete-time model close to the continuous-time one without the need for the sampling period to be as small as other commonly used discretization methods require. This fact makes possible the design of impulsive vaccination control strategies with less burden of measurements and related computations if one uses the proposed instead of other discretization methods. The proposed discretization method and the impulsive vaccination strategy designed on the resulting discretized model are the main novelties of the paper. The paper includes (i) the analysis of the positivity of the obtained discrete-time SEIR model, (ii) the study of stability of the disease-free equilibrium point of a normalized version of such a discrete-time model and (iii) the existence and the attractivity of a globally asymptotically stable disease-free periodic solution under a periodic impulsive vaccination. Concretely, the exposed and infectious subpopulations asymptotically converge to zero as time tends to infinity while the normalized subpopulations of susceptible and recovered by immunization individuals oscillate in the context of such a solution. Finally, a numerical example illustrates the theoretic results.
Reduction of the complexity of product modelling by modularisation
DEFF Research Database (Denmark)
Andreasen, Mogens Myrup
1998-01-01
The complexity in handling product aspects in design and production may be reduced by using approaches, which are applied in the field of modular engineering. This unit-oriented "spelling" of products, leading to product models with encapsulation, is introduced.......The complexity in handling product aspects in design and production may be reduced by using approaches, which are applied in the field of modular engineering. This unit-oriented "spelling" of products, leading to product models with encapsulation, is introduced....
Reduction of the complexity of product modelling by modularisation
DEFF Research Database (Denmark)
Andreasen, Mogens Myrup
1998-01-01
The complexity in handling product aspects in design and production may be reduced by using approaches, which are applied in the field of modular engineering. This unit-oriented "spelling" of products, leading to product models with encapsulation, is introduced.......The complexity in handling product aspects in design and production may be reduced by using approaches, which are applied in the field of modular engineering. This unit-oriented "spelling" of products, leading to product models with encapsulation, is introduced....
Institute of Scientific and Technical Information of China (English)
2011-01-01
On the basis of grey correlation analysis,8 factors impacting grain production prominently as follows are selected to establish indices system:yield per unit(X1),grain planting area(X2),agricultural labor forces(X3),the total power of agricultural machinery(X4),using amount of fertilizer(X5),the damaged area of crops(X6),effective irrigation area(X7),and agricultural fixed assets investment(X8).According to the relevant data of Inner Mongolia Statistical Yearbook from 1988 to 2008,we use the method of grey correlation analysis to analyze the factors impacting grain production in Inner Mongolia,quantify the correlation degree of the total grain output and all factors,and finally conclude the impacting capacity of all factors on grain production in the light of correlation degree value.The results show that yield per unit still is the principal factor impacting the total output of grain in Inner Mongolia;the area of grain planting and the area of affected crops are the two most important factors responsible for the decrease of grain output;effective irrigation area the total power of agricultural machinery are the two primary factors impacting the increase of grain output;the using amount of fertilizer shows dwindling impact on grain production;agricultural fixed assets investment still hovers at the minuscule impact degree on grain production.
Research on Digital Product Modeling Key Technologies of Digital Manufacturing
Institute of Scientific and Technical Information of China (English)
DING Guoping; ZHOU Zude; HU Yefa; ZHAO Liang
2006-01-01
With the globalization and diversification of the market and the rapid development of Information Technology (IT) and Artificial Intelligence (AI), the digital revolution of manufacturing is coming. One of the key technologies in digital manufacturing is product digital modeling. This paper firstly analyzes the information and features of the product digital model during each stage in the product whole lifecycle, then researches on the three critical technologies of digital modeling in digital manufacturing-product modeling, standard for the exchange of product model data and digital product data management. And the potential signification of the product digital model during the process of digital manufacturing is concluded-product digital model integrates primary features of each stage during the product whole lifecycle based on graphic features, applies STEP as data exchange mechanism, and establishes PDM system to manage the large amount, complicated and dynamic product data to implement the product digital model data exchange, sharing and integration.
THE ECONOMICS OF PEANUT PRODUCTION IN BULGARIA DURING THE TRANSITION PERIOD
Directory of Open Access Journals (Sweden)
Nelly BENCHEVA
2007-12-01
Full Text Available We examined peanut production systems and selected factors affecting the development of commercial peanut enterprises in Bulgaria. A survey of 220 individual farms and farm cooperatives engaged in the cultivation of peanuts was conducted during 2000 and 2002. Poor farm structure, low level of technology, and nonconformity to farm decision making impede the financial and economic development of Bulgarian peanut production and farm growth, thus limiting farm enterprises emergence into competitive economic units financially operative in a freemarket economy. The underlying cost structure, couple with small farms, averaging 0.8 ha in size, prevent farmers from capturing economies of scale, limit farm profitability and hence farm modernization. The lack of owned farm machinery, equipment and storage facilities renders the restructuring and specialization extremely difficult. However, peanut production is still a viable farm enterprise for Bulgarian farmers.
Aalbers, Scott A.
2008-01-01
Spawning periodicities of white seabass (Atractoscion nobilis) were evaluated by observing spawning behavior, by collecting eggs, and monitoring recognizable sounds produced during the release of gametes. A total of 297 spawning events were documented from 15 male and 47 female white seabass contained within the seminatural confines of a 526-m3 net pen located in Catalina Harbor, Santa Catalina Island, California. Consistent spawning occurred from March through July 2001−03, and peaked ...
Coexisting chaotic and multi-periodic dynamics in a model of cardiac alternans
Skardal, Per Sebastian
2014-01-01
The spatiotemporal dynamics of cardiac tissue is an active area of research for biologists, physicists, and mathematicians. Of particular interest is the study of period-doubling bifurcations and chaos due to their link with cardiac arrhythmogenesis. In this paper we study the spatiotemporal dynamics of a recently developed model for calcium-driven alternans in a one dimensional cable of tissue. In particular, we observe in the cable coexistence in of regions with chaotic and multi-periodic dynamics over wide ranges of parameters. We study these dynamics using global and local Lyapunov exponents and spatial trajectory correlations. Interestingly, near nodes -- or phase reversals -- low-periodic dynamics prevail, while away from the nodes the dynamics tend to be higher-periodic and eventually chaotic.
Directory of Open Access Journals (Sweden)
Edileuza Vital Galeano
2013-12-01
Full Text Available The objective of this paper is to present an empirical study of the behavior of labor industrial productivity in the regions of Brazil during the period 1996 to 2010 by groups of technology intensity. It was used the shift-share method. The results indicated that in the groups of sectors that showed positive growth rates were the competitive advantages inherent to each region that explained, in most cases, the growth of labor productivity. There was predominance of technology absorbing sectors in prejudice of sectors that generate technological spillovers. The growth of labor productivity in the extractive industry showed a upward trend, while the manufacturing industry showed downward trend, evidencing a stagnation of labor productivity at the national level. There are evidences of a reprimarization process of industrial activities through the specialization in commodities.
Cooperative behavior in periodically driven noisy integrate-fire models of neuronal dynamics
Energy Technology Data Exchange (ETDEWEB)
Bulsara, A.R. [Naval Command Control and Ocean Surveillance Center, Research, Development, Test, and Evaluation Division, Code 364, San Diego, California 92152-5000 (United States); Elston, T.C. [Center for Nonlinear Studies and Theoretical Division, MS-B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Doering, C.R. [Center for Nonlinear Studies and Theoretical Division, MS-B258, Los Alamos National Labortory, Los Alamos, New Mexico 87545 (United States); Lowen, S.B. [Electrical Engineering Department, Columbia University, New York, New York 10027 (United States); Lindenberg, K. [Department of Chemistry and Biochemistry B034, University of California at San Diego, La Jolla, California 92093-0340 (United States)
1996-04-01
The dynamics of the standard integrate-fire model and a simpler model (that reproduces the important features of the integrate-fire model under certain conditions) of neural dynamics are studied in the presence of a deterministic external driving force, taken to be time-periodic, and white background noise. Both models possess resonant phenomena in the first passage probability distribution and mean first passage time, arising from the interplay of characteristic time scales in the system. {copyright} {ital 1996 The American Physical Society.}
Patterns of lung cancer mortality in 23 countries: Application of the Age-Period-Cohort model
Directory of Open Access Journals (Sweden)
Huang Yi-Chia
2005-03-01
Full Text Available Abstract Background Smoking habits do not seem to be the main explanation of the epidemiological characteristics of female lung cancer mortality in Asian countries. However, Asian countries are often excluded from studies of geographical differences in trends for lung cancer mortality. We thus examined lung cancer trends from 1971 to 1995 among men and women for 23 countries, including four in Asia. Methods International and national data were used to analyze lung cancer mortality from 1971 to 1995 in both sexes. Age-standardized mortality rates (ASMR were analyzed in five consecutive five-year periods and for each five-year age group in the age range 30 to 79. The age-period-cohort (APC model was used to estimate the period effect (adjusted for age and cohort effects for mortality from lung cancer. Results The sex ratio of the ASMR for lung cancer was lower in Asian countries, while the sex ratio of smoking prevalence was higher in Asian countries. The mean values of the sex ratio of the ASMR from lung cancer in Taiwan, Hong Kong, Singapore, and Japan for the five 5-year period were 2.10, 2.39, 3.07, and 3.55, respectively. These values not only remained quite constant over each five-year period, but were also lower than seen in the western countries. The period effect, for lung cancer mortality as derived for the 23 countries from the APC model, could be classified into seven patterns. Conclusion Period effects for both men and women in 23 countries, as derived using the APC model, could be classified into seven patterns. Four Asian countries have a relatively low sex ratio in lung cancer mortality and a relatively high sex ratio in smoking prevalence. Factors other than smoking might be important, especially for women in Asian countries.
Periodic orbits for a discontinuous vector field arising from a conceptual model of glacial cycles
Walsh, James; Widiasih, Esther; Hahn, Jonathan; McGehee, Richard
2016-06-01
Conceptual climate models provide an approach to understanding climate processes through a mathematical analysis of an approximation to reality. Recently, these models have also provided interesting examples of nonsmooth dynamical systems. Here we develop a new conceptual model of glacial cycles consisting of a system of three ordinary differential equations defining a discontinuous vector field. Our model provides a dynamical systems framework for a mechanism previously shown to play a crucial role in glacial cycle patterns, namely, an increased ice sheet ablation rate during deglaciations. We use ad hoc singular perturbation techniques to prove the existence of a large periodic orbit crossing the discontinuity boundary, provided the ice sheet edge moves sufficiently slowly relative to changes in the snow line and temperature. Numerical explorations reveal the periodic orbit exists when the time constant for the ice sheet edge has more moderate values.
A business model framework for product life extension
Den Hollander, M.C.; Bakker, C.A.
2012-01-01
Product life extension is an increase in the utilization period of products. Design research on product life extension strategies has so far mainly focused on technical aspects of products, like ‘prevention engineering’ or ‘design for repair, maintenance and upgradability’, and on individual consume
2013-09-11
... HUMAN SERVICES Food and Drug Administration 21 CFR Part 1140 Menthol in Cigarettes, Tobacco Products... regulatory actions that FDA might take with respect to menthol in cigarettes. The Agency is taking this... other information that may inform regulatory actions FDA might take with respect to menthol...
New antitumour natural products from marine red algae: covering the period from 2003 to 2012.
Pejin, Boris; Jovanovic, Katarina K; Savic, Aleksandar G
2015-01-01
This review covers the 2003-2012 literature data published for natural products originating from marine red algae. The focus is on new antitumour substances, together with details related to the organism sourced. It emphasises 14 promising compounds (isolated from 13 species) whose chemical structures are briefly discussed.
Periodic clustering in the spectrum of quasiperiodic Kronig-Penney models
Baake, M.; Joseph, D.; Kramer, P.
1992-08-01
The continuous Schrödinger equation is discussed for the Fibonacci chain and its generalizations and compared to the tight-binding approximation. For Kronig-Penney like models, the resulting pseudo spectrum of the well-known trace map has Cantor like structures, but a subclass of models additionally shows periodic clustering with respect to the wave number k. The clusters appear at the zeros of the invariant of the trace map as a function of k. From a matrix generalization of the trace map we compute the forward scattering of the chain and find the same periodic clustering. We briefly discuss how these results extend to more general non-periodic examples.
Global Behaviors of a Chemostat Model with Delayed Nutrient Recycling and Periodically Pulsed Input
Directory of Open Access Journals (Sweden)
Kai Wang
2010-01-01
Full Text Available The dynamic behaviors in a chemostat model with delayed nutrient recycling and periodically pulsed input are studied. By introducing new analysis technique, the sufficient and necessary conditions on the permanence and extinction of the microorganisms are obtained. Furthermore, by using the Liapunov function method, the sufficient condition on the global attractivity of the model is established. Finally, an example is given to demonstrate the effectiveness of the results in this paper.
Satellite-based terrestrial production efficiency modeling
Directory of Open Access Journals (Sweden)
Obersteiner Michael
2009-09-01
Full Text Available Abstract Production efficiency models (PEMs are based on the theory of light use efficiency (LUE which states that a relatively constant relationship exists between photosynthetic carbon uptake and radiation receipt at the canopy level. Challenges remain however in the application of the PEM methodology to global net primary productivity (NPP monitoring. The objectives of this review are as follows: 1 to describe the general functioning of six PEMs (CASA; GLO-PEM; TURC; C-Fix; MOD17; and BEAMS identified in the literature; 2 to review each model to determine potential improvements to the general PEM methodology; 3 to review the related literature on satellite-based gross primary productivity (GPP and NPP modeling for additional possibilities for improvement; and 4 based on this review, propose items for coordinated research. This review noted a number of possibilities for improvement to the general PEM architecture - ranging from LUE to meteorological and satellite-based inputs. Current PEMs tend to treat the globe similarly in terms of physiological and meteorological factors, often ignoring unique regional aspects. Each of the existing PEMs has developed unique methods to estimate NPP and the combination of the most successful of these could lead to improvements. It may be beneficial to develop regional PEMs that can be combined under a global framework. The results of this review suggest the creation of a hybrid PEM could bring about a significant enhancement to the PEM methodology and thus terrestrial carbon flux modeling. Key items topping the PEM research agenda identified in this review include the following: LUE should not be assumed constant, but should vary by plant functional type (PFT or photosynthetic pathway; evidence is mounting that PEMs should consider incorporating diffuse radiation; continue to pursue relationships between satellite-derived variables and LUE, GPP and autotrophic respiration (Ra; there is an urgent need for
Bostan, C.G.; Ridder, de R.M.; Dorssen, van I.; Wolferen, van H.A.G.M.; Kuipers, L.; Hulst, van N.F.
2002-01-01
Laser interference lithography (LIL) is a technique that can be successfully used for realization of 2D periodic structures, with excellent uniformity over large areas. However, detailed modeling is needed in order to extract the optimum design parameters. In this paper, we refer to a design procedu
Model of tunnelling through periodic array of quantum dots in a magnetic field
Institute of Scientific and Technical Information of China (English)
I.Yu.Popov; S.A.Osipov
2012-01-01
A two-dimensional periodic array of quantum dots with two laterally coupled leads in a magnetic field is considered.The model of electron transport through the system based on the theory of self-adjoint extensions of symmetric operators is suggested.We obtain the formula for the transmission coefficient and investigate its dependence on the magnetic field.
Travelling waves in models of neural tissue: from localised structures to periodic waves
Meijer, Hil Gaétan Ellart; Coombes, Stephen
2014-01-01
We consider travelling waves (fronts, pulses and periodics) in spatially extended one dimensional neural field models. We demonstrate for an excitatory field with linear adaptation that, in addition to an expected stable pulse solution, a stable anti-pulse can exist. Varying the adaptation strength
Periodic solutions of delayed predator-prey model with the Beddington-DeAngelis functional response
Energy Technology Data Exchange (ETDEWEB)
Huo Haifeng [Institute of Applied Mathematics, Lanzhou University of Technology, Lanzhou, Gansu 730050 (China)]. E-mail: hfhuo@lut.cn; Li Wantong [Department of Mathematics, Lanzhou University Lanzhou, Gansu 730000 (China)]. E-mail: wtli@lzu.edu.cn; Nieto, Juan J. [Departamento de Analisis Matematico, Facultad de Matematicas, Universidad de Santiago de Compostela 15782 (Spain)]. E-mail: amnieto@usc.es
2007-07-15
By using the continuation theorem based on Gaines and Mawhin's coincidence degree, sufficient and realistic conditions are obtained for the global existence of positive periodic solutions for a delayed predator-prey model with the Beddington-DeAngelis functional response. Our results are applicable to state dependent and distributed delays.
Modeling and analysis of periodic orbits around a contact binary asteroid
Feng, J.; Noomen, R.; Visser, P.N.A.M.; Yuan, J.
2015-01-01
The existence and characteristics of periodic orbits (POs) in the vicinity of a contact binary asteroid are investigated with an averaged spherical harmonics model. A contact binary asteroid consists of two components connected to each other, resulting in a highly bifurcated shape. Here, it is repre
Mathematical Model of Equipment Unit Reliability for Determination of Optimum Overhaul Periods
Directory of Open Access Journals (Sweden)
M. A. Pasiouk
2009-01-01
Full Text Available The paper proposes a mathematical model of the equipment unit reliability with due account of operational mode effect and main influencing factors.Its application contributes to reduction of operating costs, optimization of overhaul periods, prolongation of life-service and rational usage of fleet resource.
Modeling and analysis of periodic orbits around a contact binary asteroid
Feng, J.; Noomen, R.; Visser, P.N.A.M.; Yuan, J.
2015-01-01
The existence and characteristics of periodic orbits (POs) in the vicinity of a contact binary asteroid are investigated with an averaged spherical harmonics model. A contact binary asteroid consists of two components connected to each other, resulting in a highly bifurcated shape. Here, it is
A mathematical modeling proposal for a Multiple Tasks Periodic Capacitated Arc Routing Problem
Directory of Open Access Journals (Sweden)
Cleverson Gonçalves dos Santos
2015-12-01
Full Text Available The countless accidents and incidents occurred at dams at the last years, propelled the development of politics related with dams safety. One of the strategies is related to the plan for instrumentation and monitoring of dams. The monitoring demands from the technical team the reading of the auscultation data, in order to periodically monitor the dam. The monitoring plan of the dam can be modeled as a problem of mathematical program of the periodical capacitated arcs routing program (PCARP. The PCARP is considered as a generalization of the classic problem of routing in capacitated arcs (CARP due to two characteristics: 1 Planning period larger than a time unity, as that vehicle make several travels and; 2 frequency of associated visits to the arcs to be serviced over the planning horizon. For the dam's monitoring problem studied in this work, the frequent visits, along the time horizon, it is not associated to the arc, but to the instrument with which is intended to collect the data. Shows a new problem of Multiple tasks Periodic Capacitated Arc Routing Problem and its elaboration as an exact mathematical model. The new main characteristics presented are: multiple tasks to be performed on each edge or edges; different frequencies to accomplish each of the tasks; heterogeneous fleet; and flexibility for more than one vehicle passing through the same edge at the same day. The mathematical model was implemented and examples were generated randomly for the proposed model's validation.
Hanzer, Florian; Marke, Thomas; Strasser, Ulrich
2016-04-01
In this presentation, a module for simulating technical snow production in ski areas coupled to the spatially distributed physically based hydroclimatological model AMUNDSEN is presented. The module explicitly considers individual snow guns and distributes the produced snow along the slopes. The amount of snow produced by each device is a function of its type, of wet-bulb temperature at the location, of ski area infrastructure (in terms of water supply and pumping capacity), and of snow demand. An empirical rule in the modeling for snow production, derived from common snowmaking practices, splits the winter season into a period of maximum snowmaking and a successive period of selective on-demand snowmaking. The model is exemplarily set up for a ski area in the Schladming region (Austrian Alps) using actual snowmaking infrastructure data. Integration of these data as model variables, as well as stakeholder-defined indicators and thresholds, have been implemented as defined interfaces in a coupled component model architecture. Comparison of the model results with recordings of snowmaking operation and satellite-derived snow cover maps indicate that the model is capable of accurately simulating the real-world snowmaking practice, and the combined natural and technical snow conditions on the slopes. The explicit consideration of individual snow guns and ski area infrastructure makes the model a valuable tool for scenario applications, e.g. to assess the effects of different ski area management strategies and changes in snowmaking infrastructure for climate change impact studies.
Towards a model for protein production rates
Dong, J J; Zia, R K P
2007-01-01
In the process of translation, ribosomes read the genetic code on an mRNA and assemble the corresponding polypeptide chain. The ribosomes perform discrete directed motion which is well modeled by a totally asymmetric simple exclusion process (TASEP) with open boundaries. Using Monte Carlo simulations and a simple mean-field theory, we discuss the effect of one or two ``bottlenecks'' (i.e., slow codons) on the production rate of the final protein. Confirming and extending previous work by Chou and Lakatos, we find that the location and spacing of the slow codons can affect the production rate quite dramatically. In particular, we observe a novel ``edge'' effect, i.e., an interaction of a single slow codon with the system boundary. We focus in detail on ribosome density profiles and provide a simple explanation for the length scale which controls the range of these interactions.
Towards a Model for Protein Production Rates
Dong, J. J.; Schmittmann, B.; Zia, R. K. P.
2007-07-01
In the process of translation, ribosomes read the genetic code on an mRNA and assemble the corresponding polypeptide chain. The ribosomes perform discrete directed motion which is well modeled by a totally asymmetric simple exclusion process (TASEP) with open boundaries. Using Monte Carlo simulations and a simple mean-field theory, we discuss the effect of one or two "bottlenecks" (i.e., slow codons) on the production rate of the final protein. Confirming and extending previous work by Chou and Lakatos, we find that the location and spacing of the slow codons can affect the production rate quite dramatically. In particular, we observe a novel "edge" effect, i.e., an interaction of a single slow codon with the system boundary. We focus in detail on ribosome density profiles and provide a simple explanation for the length scale which controls the range of these interactions.
Improving geomagnetic field models for the period 1980-1999 using Ørsted data
Ultré-Guérard, P.; Jault, D.; Alexandrescu, M.; Achache, J.
1998-08-01
The Danish satellite Ørsted is due to be launched in 1998, and should provide, for the first time since the Magsat mission (1979-1980), a dense and global coverage of the Earth's surface with vector measurements of the magnetic field. In this paper, we compare the expected error in the main field models computed for the 1970-1999 time interval using observatory data, with or without the a priori information given by the knowledge of the field at both Magsat and Ørsted epochs. This work is based on the reasonable hypothesis that the main field models derived from Ørsted data will be as accurate as the Magsat models. The a priori information given by the Magsat and Ørsted models is based on a linear behaviour of the rate-of-change of the field throughout this period, plus a noise level which can be estimated as a function of time and degree from past field changes. The expected error in the models computed for the 1980-1999 period with a priori information appears to be significantly smaller than the expected error in the models computed without this information. This result is related to the heterogeneous distribution of the observatories over the Earth surface. Consequently, when the Ørsted data is available, improved models can be computed for the 1980-1999 period particularly in regions without observatory data. This method with a priori information may allow the use of the same set of observatories throughout the entire period. Indeed, our method alleviates the requirement of a very dense data distribution.
Directory of Open Access Journals (Sweden)
Roniram Pereira da Silva
2014-04-01
Full Text Available The planting of diversified crops during the sugarcane fallow period can improve the chemical and physical properties and increase the production potential of the soil for the next sugarcane cycle. The primary purpose of this study was to assess the influence of various soil uses during the sugarcane fallow period on soil chemical and physical properties and productivity after the first sugarcane harvest. The experiment was conducted in two areas located in Jaboticabal, São Paulo State, Brazil (21º 14' 05'' S, 48º 17' 09'' W with two different soil types, namely: an eutroferric Red Latosol (RLe with high-clay texture (clay content = 680 g kg-1 and an acric Red Latosol (RLa with clayey texture (clay content = 440 g kg-1. A randomized block design with five replications and four treatments (crop sequences was used. The crop sequences during the sugarcane fallow period were soybean/millet/soybean, soybean/sunn hemp/soybean, soybean/fallow/soybean, and soybean. Soil use was found not to affect chemical properties and sugarcane productivity of RLe or RLa. The soybean/millet/soybean sequence improved aggregation in the acric Latosol.
Allah Taleizadeh, Ata; Niaki, Seyed Taghi Akhavan; Aryanezhad, Mir-Bahador
2010-10-01
While the usual assumptions in multi-periodic inventory control problems are that the orders are placed at the beginning of each period (periodic review) or depending on the inventory level they can happen at any time (continuous review), in this article, we relax these assumptions and assume that the periods between two replenishments of the products are independent and identically distributed random variables. Furthermore, assuming that the purchasing price are triangular fuzzy variables, the quantities of the orders are of integer-type and that there are space and service level constraints, total discount are considered to purchase products and a combination of back-order and lost-sales are taken into account for the shortages. We show that the model of this problem is a fuzzy mixed-integer nonlinear programming type and in order to solve it, a hybrid meta-heuristic intelligent algorithm is proposed. At the end, a numerical example is given to demonstrate the applicability of the proposed methodology and to compare its performance with one of the existing algorithms in real world inventory control problems.
Using genetic algorithm to solve a new multi-period stochastic optimization model
Zhang, Xin-Li; Zhang, Ke-Cun
2009-09-01
This paper presents a new asset allocation model based on the CVaR risk measure and transaction costs. Institutional investors manage their strategic asset mix over time to achieve favorable returns subject to various uncertainties, policy and legal constraints, and other requirements. One may use a multi-period portfolio optimization model in order to determine an optimal asset mix. Recently, an alternative stochastic programming model with simulated paths was proposed by Hibiki [N. Hibiki, A hybrid simulation/tree multi-period stochastic programming model for optimal asset allocation, in: H. Takahashi, (Ed.) The Japanese Association of Financial Econometrics and Engineering, JAFFE Journal (2001) 89-119 (in Japanese); N. Hibiki A hybrid simulation/tree stochastic optimization model for dynamic asset allocation, in: B. Scherer (Ed.), Asset and Liability Management Tools: A Handbook for Best Practice, Risk Books, 2003, pp. 269-294], which was called a hybrid model. However, the transaction costs weren't considered in that paper. In this paper, we improve Hibiki's model in the following aspects: (1) The risk measure CVaR is introduced to control the wealth loss risk while maximizing the expected utility; (2) Typical market imperfections such as short sale constraints, proportional transaction costs are considered simultaneously. (3) Applying a genetic algorithm to solve the resulting model is discussed in detail. Numerical results show the suitability and feasibility of our methodology.
Xu, Kesheng; Maidana, Jean P.; Caviedes, Mauricio; Quero, Daniel; Aguirre, Pablo; Orio, Patricio
2017-01-01
In this article, we describe and analyze the chaotic behavior of a conductance-based neuronal bursting model. This is a model with a reduced number of variables, yet it retains biophysical plausibility. Inspired by the activity of cold thermoreceptors, the model contains a persistent Sodium current, a Calcium-activated Potassium current and a hyperpolarization-activated current (Ih) that drive a slow subthreshold oscillation. Driven by this oscillation, a fast subsystem (fast Sodium and Potassium currents) fires action potentials in a periodic fashion. Depending on the parameters, this model can generate a variety of firing patterns that includes bursting, regular tonic and polymodal firing. Here we show that the transitions between different firing patterns are often accompanied by a range of chaotic firing, as suggested by an irregular, non-periodic firing pattern. To confirm this, we measure the maximum Lyapunov exponent of the voltage trajectories, and the Lyapunov exponent and Lempel-Ziv's complexity of the ISI time series. The four-variable slow system (without spiking) also generates chaotic behavior, and bifurcation analysis shows that this is often originated by period doubling cascades. Either with or without spikes, chaos is no longer generated when the Ih is removed from the system. As the model is biologically plausible with biophysically meaningful parameters, we propose it as a useful tool to understand chaotic dynamics in neurons. PMID:28344550
Groundwater flow modelling of periods with periglacial and glacial climate conditions - Laxemar
Energy Technology Data Exchange (ETDEWEB)
Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden)); Zugec, Nada (Bergab, Goeteborg (Sweden))
2010-12-15
As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report is concerned with the modelling of a repository at the Laxemar-Simpevarp site during periglacial and glacial climate conditions as a comparison to corresponding modelling carried out for Forsmark /Vidstrand et al. 2010/. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle at Laxemar. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 13,000 years. The simulation results comprise pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance and the bedrock hydraulic and transport properties
Dilepton production with the SMASH model
Weil, Janus; Petersen, Hannah
2016-01-01
In this work the SMASH model is presented ("Simulating Many Accelerated Strongly-Interacting Hadrons"), a next-generation hadronic transport approach, which is designed to describe the non-equilibrium evolution of hadronic matter in heavy-ion collisions. We discuss first dilepton spectra obtained with SMASH in the few-GeV energy range of GSI/FAIR, where the dynamics of hadronic matter is dominated by the production and decay of various resonance states. In particular we show how electromagnetic transition form factors can emerge in a transport picture under the hypothesis of vector-meson dominance.
Mutoh, Atsuko; Tokuhara, Shinya; Kanoh, Masayoshi; Oboshi, Tamon; Kato, Shohei; Itoh, Hidenori
It is generally thought that living things have trends in their preferences. The mechanism of occurrence of another trends in successive periods is concerned in their conformity. According to social impact theory, the minority is always exists in the group. There is a possibility that the minority make the transition to the majority by conforming agents. Because of agent's promotion of their conform actions, the majority can make the transition. We proposed an evolutionary model with both genes and memes, and elucidated the interaction between genes and memes on sexual selection. In this paper, we propose an agent model for sexual selection imported the concept of conformity. Using this model we try an environment where male agents and female agents are existed, we find that periodic phenomena of fashion are expressed. And we report the influence of conformity and differentiation on the transition of their preferences.
A Hand-Foot-and-Mouth Disease Model with Periodic Transmission Rate in Wenzhou, China
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Yeting Zhu
2014-01-01
Full Text Available We establish an SEIQRS epidemic model with periodic transmission rate to investigate the spread of seasonal HFMD in Wenzhou. The value of this study lies in two aspects. Mathematically, we show that the global dynamics of the HFMD model can be governed by its reproduction number R0; if R01, the model has at least one positive periodic solution and is uniformly persistent, which indicates that HFMD becomes an endemic disease. Epidemiologically, based on the statistical data of HFMD in Wenzhou, we find that the HFMD becomes an endemic disease and will break out in Wenzhou. One of the most interesting findings is that, for controlling the HFMD spread, we must increase the quarantined rate or decrease the treatment cycle.
Stage-dependent model for Hantavirus infection: The effect of the initial infection-free period
Reinoso, José A.; de la Rubia, F. Javier
2013-04-01
We propose a stage-dependent model with constant delay to study the effect of the initial infection-free period on the spread of Hantavirus infection in rodents. We analyze the model under various extreme weather conditions, in the context of the El Niño-La Niña Southern Oscillation phenomenon, and show how these variations determine the evolution of the system significantly. When the scenario corresponds to El Niño, the system presents a demographic explosion and a delayed outbreak of Hantavirus infection, whereas if the scenario is the opposite there is a rapid decline of the population, but with a possible persistence period that may imply a considerable risk for public health, a fact that is in agreement with available field data. We use the model to simulate a historical evolution that resembles the processes that occurred in the 1990s.
THE EXISTENCE OF POSITIVE PERIODIC SOLUTIONS IN A LOGISTIC DIFFERENCE MODEL WITH A FEEDBACK CONTROL
Institute of Scientific and Technical Information of China (English)
刘智钢; 陈安平
2004-01-01
Consider the following nonautonomous delayed periodic logistic difference model with feedback control term N(k+1)=N(k)exp[r(k)-a1(k)N(k)-a2(k)N(k-τ(k))-c(k)u(k)],Δu(k)=-a(k)u(k)+b(k)N(k-τ(k)), which describes the evolution of a single species. The existence of a positive periodic solution is established by using the method of Mawhin's coincidence degree. This work has important significance in both theory and applications.
Qualitative analysis of an integro-differential equation model of periodic chemotherapy
Jain, Harsh Vardhan
2012-12-01
An existing model of tumor growth that accounts for cell cycle arrest and cell death induced by chemotherapy is extended to simulate the response to treatment of a tumor growing in vivo. The tumor is assumed to undergo logistic growth in the absence of therapy, and treatment is administered periodically rather than continuously. Necessary and sufficient conditions for the global stability of the cancer-free equilibrium are derived and conditions under which the system evolves to periodic solutions are determined. © 2012 Elsevier Ltd. All rights reserved.
A reaction-diffusion SIS epidemic model in an almost periodic environment
Wang, Bin-Guo; Li, Wan-Tong; Wang, Zhi-Cheng
2015-12-01
A susceptible-infected-susceptible almost periodic reaction-diffusion epidemic model is studied by means of establishing the theories and properties of the basic reproduction ratio {R0}. Particularly, the asymptotic behaviors of {R0} with respect to the diffusion rate {DI} of the infected individuals are obtained. Furthermore, the uniform persistence, extinction and global attractivity are presented in terms of {R0}. Our results indicate that the interaction of spatial heterogeneity and temporal almost periodicity tends to enhance the persistence of the disease.
Periodic Packing Mode for Trickle-Bed Reactors：Experiments and Modeling
Institute of Scientific and Technical Information of China (English)
刘国柱; 米镇涛
2004-01-01
A periodic packing mode of trickle-bed reactor (TBR) for the gas limited reaction was proposed. Hydrogenation of 2-ethylanthraquinone over Pd/A12Oa in a laboratory-scale TBR was taken as a test reaction for determining whether the periodic packing mode is advantageous. The effects of operating conditions and packing type on TBR performance were experimentally examined to demonstrate the cause-effect relationships. A mathematic model of TBR considering axial dispersion and fractional wetting was developed to quantitatively illuminate the reason of performance enhancement.
Periodic model of LTA framework containing various non-tetrahedral cations
Koleżyński, A.; Mikuła, A.; Król, M.
2016-03-01
A simplified periodic model of Linde Type A zeolite (LTA) structure with various selected mono- and di-valent extra-framework cations was formulated. Ab initio calculations (geometry optimization and vibrational spectra calculations) using the proposed model were carried out by means of Crystal09 program. The resulting structures and simulated spectra were analyzed in detail and compared with the experimental ones. The presented results show that in most cases the proposed model agrees well with experimental results. Individual bands were assigned to respective normal modes of vibration and the changes resulting from the selective substitution of extra framework cations were described and explained.
Periodic model of LTA framework containing various non-tetrahedral cations.
Koleżyński, A; Mikuła, A; Król, M
2016-03-15
A simplified periodic model of Linde Type A zeolite (LTA) structure with various selected mono- and di-valent extra-framework cations was formulated. Ab initio calculations (geometry optimization and vibrational spectra calculations) using the proposed model were carried out by means of Crystal09 program. The resulting structures and simulated spectra were analyzed in detail and compared with the experimental ones. The presented results show that in most cases the proposed model agrees well with experimental results. Individual bands were assigned to respective normal modes of vibration and the changes resulting from the selective substitution of extra framework cations were described and explained.
Yang, Shiju; Li, Chuandong; Huang, Tingwen
2016-03-01
The problem of exponential stabilization and synchronization for fuzzy model of memristive neural networks (MNNs) is investigated by using periodically intermittent control in this paper. Based on the knowledge of memristor and recurrent neural network, the model of MNNs is formulated. Some novel and useful stabilization criteria and synchronization conditions are then derived by using the Lyapunov functional and differential inequality techniques. It is worth noting that the methods used in this paper are also applied to fuzzy model for complex networks and general neural networks. Numerical simulations are also provided to verify the effectiveness of theoretical results.
Periodic Orbits for a Discontinuous Vector Field Arising from a Conceptual Model of Glacial Cycles
Walsh, James; Hahn, Jonathan; McGehee, Richard
2015-01-01
Conceptual climate models provide an approach to understanding climate processes through a mathematical analysis of an approximation to reality. Recently, these models have also provided interesting examples of nonsmooth dynamical systems. Here we discuss a conceptual model of glacial cycles consisting of a system of three ordinary differential equations defining a discontinuous vector field. We show that this system has a large periodic orbit crossing the discontinuity boundary. This orbit can be interpreted as an intrinsic cycling of the Earth's climate giving rise to alternating glaciations and deglaciations.
The Goodwin model revisited: Hopf bifurcation, limit-cycle, and periodic entrainment
Woller, Aurore; Gonze, Didier; Erneux, Thomas
2014-08-01
The three-variable Goodwin oscillator is a minimal model demonstrating the emergence of oscillations in simple biochemical feedback systems. As a prototypical oscillator, this model was extensively studied from a theoretical point of view and applied to various biological systems, including circadian clocks. Here, we reexamine this model, derive analytically the amplitude equation near the Hopf bifurcation and investigate the effect of a periodic modulation of the oscillator. In particular, we compare the entrainment performance when the free oscillator displays either self-sustained or damped oscillations. We discuss the results in the context of circadian oscillators.
Institute of Scientific and Technical Information of China (English)
Hu Xianwen; Gao Lihua; Li Zuohu; Xiao Chengzu; Xu Zhaoping
2006-01-01
An rCHO cell line expressing recombinant human prourokinase (pro-UK at the level of 5μg/106cells/d was cultivated on Cytopore cellulose porous microcarriers in a 7.5L Biostat CT stirred tank reactor. A periodic pressure oscillation of 0.04 MPa and 0.04 Hz was adopted to introduce a physical stimulus on the rCHO cells and to improve mass transfer characteristic between cells and medium in the process of porous microcarrier CHO cell culture. Compared to constant pressure culture, the oscillation culture didn't influence specific cell growth rate significantly, but could enhance the pro-UK specific production by 10%～40%, and reduce production of lactate by 10%～30%. In the perfusion culture of recombinant CHO cell with serum-free medium for 67 days, cell density could reach 2.64×107/ml, the maximal prourokinase concentration in harvested supernatant was about 118mg/L, a total of 21.1 grams of prourokinase was produced in 313 liters of supernatant. In conclusion, the perfusion cell culture with periodic pressure oscillation can enhance the production of recombinant protein and increase the reactor specific productivity.
Moeeni, Hamid; Bonakdari, Hossein; Fatemi, Seyed Ehsan
2017-04-01
Because time series stationarization has a key role in stochastic modeling results, three methods are analyzed in this study. The methods are seasonal differencing, seasonal standardization and spectral analysis to eliminate the periodic effect on time series stationarity. First, six time series including 4 streamflow series and 2 water temperature series are stationarized. The stochastic term for these series obtained with ARIMA is subsequently modeled. For the analysis, 9228 models are introduced. It is observed that seasonal standardization and spectral analysis eliminate the periodic term completely, while seasonal differencing maintains seasonal correlation structures. The obtained results indicate that all three methods present acceptable performance overall. However, model accuracy in monthly streamflow prediction is higher with seasonal differencing than with the other two methods. Another advantage of seasonal differencing over the other methods is that the monthly streamflow is never estimated as negative. Standardization is the best method for predicting monthly water temperature although it is quite similar to seasonal differencing, while spectral analysis performed the weakest in all cases. It is concluded that for each monthly seasonal series, seasonal differencing is the best stationarization method in terms of periodic effect elimination. Moreover, the monthly water temperature is predicted with more accuracy than monthly streamflow. The criteria of the average stochastic term divided by the amplitude of the periodic term obtained for monthly streamflow and monthly water temperature were 0.19 and 0.30, 0.21 and 0.13, and 0.07 and 0.04 respectively. As a result, the periodic term is more dominant than the stochastic term for water temperature in the monthly water temperature series compared to streamflow series.
The mathematical model that describes the periodic spouting of a geyser induced by boiling
Kagami, Hiroyuki
2017-04-01
We have derived and modified the dynamical model of a geyser induced by gas inflow and regular or irregular spouting dynamics of geysers induced by gas inflow has been reproduced by the model. On the other hand, though we have derived the dynamical model of a geyser induced by boiling, periodic change between the spouting state and the pause state has not been adequately modeled by the model. In this connection, concerning a geyser induced by gas inflow we have proposed the model as described below. Because pressure in the spouting tube decreases obeying to the Bernoulli's theorem when the spouting state begins and water in the spouting tube begins to flow, inflow of groundwater into the spouting tube occurs. When the amount of this inflow reaches a certain amount, the spouting state transforms to the pause state. In this study, by applying this idea to the dynamical model of a geyser induced by boiling, the periodic change between the spouting state and the pause state could be reappeared. As a result, the whole picture of the spouting mechanism of a geyser induced by boiling became clear. This research results would give hints on engineering repair in order to prevent the weakening or the depletion of the geyser. And this study would be also useful for protection of geysers as tourism and environmental resources.
Fluctuations around Periodic BPS-Density Waves in the Calogero Model
Bardek, V; Meljanac, S
2010-01-01
The collective field formulation of the Calogero model supports periodic density waves. An important set of such density waves is a two-parameter family of BPS solutions of the equations of motion of the collective field theory. One of these parameters is essentially the average particle density, which determines the period, while the other parameter determines the amplitude. These BPS solutions are sometimes referred to as "small amplitude waves" since they undulate around their mean density, but never vanish. We present complete analysis of quadratic fluctuations around these BPS solutions. The corresponding fluctuation hamiltonian (i.e., the stability operator) is diagonalized in terms of bosonic creation and annihilation operators which correspond to the complete orthogonal set of Bloch-Floquet eigenstates of a related periodic Schr\\"odinger hamiltonian, which we derive explicitly. Remarkably, the fluctuation spectrum is independent of the parameter which determines the density wave's amplitude. As a cons...
The productivity of various pure breed and cross breed of imported pigs during lactation period
Directory of Open Access Journals (Sweden)
Djamuara Aritonang
2001-03-01
Full Text Available A study has been conducted to evaluate the productivity of pure breeds and cross breeds of imported pigs. Sixteen strains of pigs with five best sows were selected based on litter size and birth weight on the second parity. The results of the study showed that the pure breed performance was better than the cross breeds, as shown by the litter size, birth and weaned weight, less mortality, better mothering ability and better feed efficiency. Between pure breed, the Landrace and Yorkshire were better than other sows and between the cross breed, the LH and YL performed better than other crossbreeds. It is recommended that the pure breed especially Landrace and Yorkshire and LH and YL of cross breed are better than others
A nonlocal and periodic reaction-diffusion-advection model of a single phytoplankton species.
Peng, Rui; Zhao, Xiao-Qiang
2016-02-01
In this article, we are concerned with a nonlocal reaction-diffusion-advection model which describes the evolution of a single phytoplankton species in a eutrophic vertical water column where the species relies solely on light for its metabolism. The new feature of our modeling equation lies in that the incident light intensity and the death rate are assumed to be time periodic with a common period. We first establish a threshold type result on the global dynamics of this model in terms of the basic reproduction number R0. Then we derive various characterizations of R0 with respect to the vertical turbulent diffusion rate, the sinking or buoyant rate and the water column depth, respectively, which in turn give rather precise conditions to determine whether the phytoplankton persist or become extinct. Our theoretical results not only extend the existing ones for the time-independent case, but also reveal new interesting effects of the modeling parameters and the time-periodic heterogeneous environment on persistence and extinction of the phytoplankton species, and thereby suggest important implications for phytoplankton growth control.
Long-period modelling of MEDNET waveforms for the December 13, 1990 Eastern Sicily earthquake
Directory of Open Access Journals (Sweden)
N. A. Pino
1995-06-01
Full Text Available The availability of broad-band digital data allow "the analysis" of the seismic signal in the low-noise frequency band for structural and seismic source studies, We model complete seismograms -surface and body waves - for the December 13, 1 990, Eastern Sicily earthquake, recorded at regional distances on the MEDNET stations AQU, BNI and KEG, The inversion for the moment tensor is carried out following two approaches: a a model-independent stralegy to fit complete seismograms in the 100-130 s period range; b the calibration of phase velocity curves along each path to fit surface waves in the 40-100 s range, Both methodologies yield stable and consistent results: the 1990 Eastern Sicily earthquake had a seismic moment of M/o = 37 x 1024 dyne.cm, corresponding lo magnitude values of mb = 5,5, Ms = 5,7, Mw = ML = 5.8. In a second stage, synthetic seismograms arc generated by full reflectivity in the 5-50 s period range, with a new code based on the "minors" integration. By modelling surface waves in the 30-50 s range and body waves to 5 s periods, we derive average velocity models for the Central and Eastern Mediterranean, and constrain the hypocenter of the 1990 Eastern Sicily earthquake to be in the 13-17 km depth range.
Modeling the time-periodicity of in-degree distributions in scientific citation networks
Liu, Qi; Xie, Zonglin; Dong, Enming; Li, Jianping
2016-01-01
In a range of citation networks, the in-degree distributions boast time-periodicity---the distributions of citations per article published each year present similar scale-free tails. This phenomenon can be regarded as a consequence of the emergence of hot topics and the existence of the "burst" phenomenon. With this inference considered, a geometric model based on our previous study is established, in which the sizes of the influence zones of nodes follow the same power-law distribution and decrease with their ages. The model successfully reproduces the time-periodicity of the in-degree distributions of the empirical data, and accounts for the presence of citation burst as well. Moreover, a reasonable explanation for the emergence of the scale-free tails by regarding the citation behavior between articles as a "yes/no" experiment is presented. The model can also predict the time-periodicity of the local clustering coefficients, which indicates that the model is a good tool in researches on the evolutionary me...
Enhancement of nisin production by Lactococcus lactis in periodically re-alkalized cultures.
Guerra, Nelson Pérez; Castro, Lorenzo Pastrana
2003-10-01
Synthesis of nisin as well as biomass production by Lactococcus lactis subsp. lactis CECT (Colección Española de Cultivos Tipo) 539 on both hydrolysed mussel-processing waste and whey medium were followed in three fixed volume fed-batch fermentations, with re-alkalization cycles. The two cultures on mussel-processing waste (MPW) were fed with a 240 g/l concentrated glucose and with a concentrated MPW (about 100 g of glucose/l). The culture on whey was fed with a mixture of concentrated whey (48 g of total sugars/l) and a 400 g/l concentrated lactose. The three cultures were mainly characterized with higher nisin titres [49.7, 109.6 and 124.7 bacteriocin activity units (AU)/ml respectively] compared with the batch process on de Man, Rogosa and Sharpe [(1960) J. Appl. Bacteriol. 23, 130-135] medium (49.6 AU/ml), MPW (9.5 AU/ml) and whey (22.5 AU/ml) [1 AU/ml is the amount of antibacterial compound needed to obtain 50% growth inhibition (LD50) compared with control tubes]. In the three fed-batch cultures a shift from homolactic to mixed-acid fermentation was observed, and other products (acetic acid, butane-2,3-diol or ethanol) in addition to lactic acid were detectable in the medium. However, their contributions to the total antibacterial activity of the post-incubates (the cell-free culture supernatant obtained at the end of the fermentation process) of L. lactis CECT 539 against Carnobacterium piscicola CECT 4020 were very low.
Statistical modelling of fine red wine production
Directory of Open Access Journals (Sweden)
María Rosa Castro
2010-05-01
Full Text Available Producing wine is a very important economic activity in the province of San Juan in Argentina; it is therefore most important to predict production regarding the quantity of raw material needed. This work was aimed at obtaining a model relating kilograms of crushed grape to the litres of wine so produced. Such model will be used for predicting precise future values and confidence intervals for determined quantities of crushed grapes. Data from a vineyard in the province of San Juan was thus used in this work. The sampling coefficient of correlation was calculated and a dispersion diagram was then constructed; this indicated a li- neal relationship between the litres of wine obtained and the kilograms of crushed grape. Two lineal models were then adopted and variance analysis was carried out because the data came from normal populations having the same variance. The most appropriate model was obtained from this analysis; it was validated with experimental values, a good approach being obtained.
Institute of Scientific and Technical Information of China (English)
Li Zhu; Zhong Cheng Yang; Ao Li; De Chang Cheng
2000-01-01
AIM To investigate the changes of gastric acid production and its mechanism in shock period of severe burn in rats.METHODS A rat model with 30% TBSA fullthickness burn injury was employed and the gastric acid production, together with gastric mucosal blood flow (GMBF) and energy charge ( EC ) were measured serially within 48h postburn.RESULTS The gastric acid production in the acute shock period was markedly inhibited after severe burn injury. At the 3rd h postburn, the gastric juice volume, total acidity and acid output were already significantly decreased (P＜0.01), and reached the lowest point,0.63mL/L ± 0.20mL/L, 10.81mmol/L ±2.58mmol/L and 2.23 mmol/h ± 0.73mmol/h respectively, at the 12th h postburn. Although restored to some degree 24 h after thermal injury, the variables above were still statistically lower, compared with those of control animals at the 48th h postburn. The GMBF and EC were also significantly reduced after severe burns, consistent with the trend of gastric acid production changes.CONCLUSION Gastric acid production, as well as GMBF and EC was predominantly decreased in the early postburn stage, suggesting that gastric mucosal ischemia and hypoxia with resultant disturbance in energy metabolism, but not gastric acid proper, might be the decisive factor in the pathogenesis of AGML after thermal injury, and that the preventive use of anti-acid drugs during burn shock period was unreasonable in some respects. Therefore,taking effective measures to improve gastric mucosal blood perfusion as early as possible postburn might be more preferable for the AGML prevention and treatment.
Striped periodic minimizers of a two-dimensional model for martensitic phase transitions
Giuliani, Alessandro
2010-01-01
In this paper we consider a simplified two-dimensional scalar model for the formation of mesoscopic domain patterns in martensitic shape-memory alloys at the interface between a region occupied by the parent (austenite) phase and a region occupied by the product (martensite) phase, which can occur in two variants (twins). The model, first proposed by Kohn and Mueller, is defined by the following functional:
THE PERIODIC CAPACITATED ARC ROUTING PROBLEM LINEAR PROGRAMMING MODEL,METAHEURISTIC AND LOWER BOUNDS
Institute of Scientific and Technical Information of China (English)
Feng CHU; Nacima LABADI; Christian PRINS
2004-01-01
The Periodic Capacitated Arc Routing Problem (PCARP) generalizes the well known NP-hard Capacitated Arc Routing Problem (CARP) by extending the single period to multi-period horizon.The Capacitated Arc Routing Problem (CARP) is defined on an undirected network in which a fleet of identical vehicles is based at a depot node. A subset of edges, called tasks, must be serviced by a vehicle. The CARP consists of determining a set of feasible vehicle trips that minimizes the total cost of traversed edges. The PCARP involves the assignment of tasks to periods and the determination of vehicles trips in each period, to minimize the total cost on the whole horizon. This new problem arises in various real life applications such as waste collection, mail delivery, etc. In this paper, a new linear programming model and preliminary lower bounds based on graph transformation are proposed. A meta-heuristic approach - Scatter Search (SS) is developed for the PCARP and evaluated on a large variety of instances.
Regional Oil Extraction and Consumption: A simple production model for the next 35 years Part I
Dittmar, Michael
2016-01-01
The growing conflicts in and about oil exporting regions and speculations about volatile oil prices during the last decade have renewed the public interest in predictions for the near future oil production and consumption. Unfortunately, studies from only 10 years ago, which tried to forecast the oil production during the next 20-30 years, failed to make accurate predictions for today's global oil production and consumption. Forecasts using economic growth scenarios, overestimated the actual oil production, while models which tried to estimate the maximum future oil production/year, using the official country oil reserve data, predicted a too low production. In this paper, a new approach to model the maximal future regional and thus global oil production (part I) and consumption (part II) during the next decades is proposed. Our analysis of the regional oil production data during past decades shows that, in contrast to periods when production was growing and growth rates varied greatly from one country to ano...
Model, Proxy and Isotopic Perspectives on the East African Humid Period
Tierney, Jessica E.; Lewis, Sophie C.; Cook, Benjamin I.; LeGrande, Allegra N.; Schmidt, Gavin A.
2011-01-01
Both North and East Africa experienced more humid conditions during the early and mid-Holocene epoch (11,000-5000yr BP; 11-5 ka) relative to today. The North African Humid Period has been a major focus of paleoclimatic study, and represents a response of the hydrological cycle to the increase in boreal summer insolation and associated ocean, atmosphere and land surface feedbacks. Meanwhile, the mechanisms that caused the coeval East African Humid Period are poorly understood. Here, we use results from isotopeenabled coupled climate modeling experiments to investigate the cause of the East African Humid Period. The modeling results are interpreted alongside proxy records of both water balance and the isotopic composition of rainfall. Our simulations show that the orbitally-induced increase in dry season precipitation and the subsequent reduction in precipitation seasonality can explain the East African Humid Period, and this scenario agrees well with regional lake level and pollen paleoclimate data. Changes in zonal moisture flux from both the Atlantic and Indian Ocean account for the simulated increase in precipitation from June through November. Isotopic paleoclimate data and simulated changes in moisture source demonstrate that the western East African Rift Valley in particular experienced more humid conditions due to the influx of Atlantic moisture and enhanced convergence along the Congo Air Boundary. Our study demonstrates that zonal changes in moisture advection are an important determinant of climate variability in the East African region.
Sustainable Irrigation Allocation Model for Dry and Wet Periods using Reservoir Storage and Inflow
Surianarayanan, S.; Suribabu, C. R.; Ramakrishnan, K.
2017-07-01
The dry period agriculture is inevitable both for the farmers for their earning, and for the soil for its fertility by crop-rotation. In tropical countries like INDIA, dry period agriculture becomes difficult because of less (or) no rain fall. Hence a simple water balancing model for irrigation scheduling, using the measure “Volumetric Reliability” is prepared in this paper, with the storage and inflow of a reservoir both for the dry and wet periods. The case-study is done for a reservoir in INDIA with thirty one years of hydrological data(from 1982 to 2012). The objective of this paper is to prepare a simple water balance model taking 10 days periods of demand and supply for ID crop(Irrigated Dry crop, ground nut) with usage of volumetric reliability concept for the periods of deficiency and adoption of less water requirement crops to reduce the water-stress during critical periods of crop growth, and finally arrive at a feasible allocation schedule for the success of agriculture and the yield throughout the year both for wet and dry crops with the available storage on the start of irrigation for a particular year. The reservoir is divided for storages such as full, deficient and critical storages. The starting storage for the dry period from January is used after adequate allocation for wet crops, the quantity for riparian rights and for drinking water, for the sustainability. By the water-balancing, the time-series for thirty one years, it is found that for twenty two years the demand for the ID crops is satisfied with the storage in the reservoir, and in the remaining years of deficient inflows, for three years (1986,1996,2004)the demand is managed by using the safe reliability factor for demand which can nullify the deficit in demand for the whole supply period. But it is genuine to assure that the reduction in the amount of water for each 10 days periods should not exceed the survival limit of the crop. Necessary soil-moisture must be ensured in the crop
DEFICIENT INFORMATION MODELING OF MECHANICAL PRODUCTS FOR CONCEPTUAL SHAPE DESIGN
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
In allusion to the deficient feature of product information in conceptual design, a framework of deficient information modeling for conceptual shape design is put forward, which includes qualitative shape modeling (a qualitative solid model), uncertain shape modeling (an uncertain relation model) and imprecise shape modeling (an imprecise region model). In the framework, the qualitative solid model is the core, which represents qualitatively (using symbols) the conceptual shapes of mechanical products. The uncertain relation model regarding domain relations as objects and the imprecise region model regarding domains as objects are used to deal with the uncertain and imprecise issues respectively, which arise from qualitative shape modeling or exist in product information itself.
Proposal for product development model focused on ce certification methodology
Directory of Open Access Journals (Sweden)
Nathalia Marcia Goulart Pinheiro
2015-09-01
Full Text Available This paper presents a critical analysis comparing 21 product development models in order to identify whether these structures meet the demands Product Certification of the European Community (CE. Furthermore, it presents a product development model, comprising the steps in the models analyzed, including improvements in activities for referred product certification. The proposed improvements are justified by the growing quest for the internationalization of products and processes within companies.
On Accuracy Order of Fourier Coefficients Computation for Periodic Signal Processing Models
Korytov, I. V.; Golosov, S. E.
2016-08-01
The article is devoted to construction piecewise constant functions for modelling periodic signal. The aim of the paper is to suggest a way to avoid discontinuity at points where waveform values are obtained. One solution is to introduce shifted step function whose middle points within its partial intervals coincide with points of observation. This means that large oscillations of Fourier partial sums move to new jump discontinuities where waveform values are not obtained. Furthermore, any step function chosen to model periodic continuous waveform determines a way to calculate Fourier coefficients. In this case, the technique is certainly a weighted rectangular quadrature rule. Here, the weight is either unit or trigonometric. Another effect of the solution consists in following. The shifted function leads to application midpoint quadrature rules for computing Fourier coefficients. As a result the formula for zero coefficient transforms into trapezoid rule. In the same time, the formulas for other coefficients remain of rectangular type.
Multi-Period Model of Portfolio Investment and Adjustment Based on Hybrid Genetic Algorithm
Institute of Scientific and Technical Information of China (English)
RONG Ximin; LU Meiping; DENG Lin
2009-01-01
This paper proposes a multi-period portfolio investment model with class constraints, transaction cost, and indivisible securities. When an investor joins the securities market for the first time, he should decide on portfolio investment based on the practical conditions of securities market. In addition, investors should adjust the portfolio according to market changes, changing or not changing the category of risky securities. Markowitz mean-variance approach is applied to the multi-period portfolio selection problems. Because the sub-models are optimal mixed integer program, whose objective function is not unimodal and feasible set is with a particular structure, traditional optimization method usually fails to find a globally optimal solution. So this paper employs the hybrid genetic algorithm to solve the problem. Investment policies that accord with finance market and are easy to operate for investors are put forward with an illustration of application.
Busy period analysis, rare events and transient behavior in fluid flow models
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Søren Asmussen
1994-01-01
Full Text Available We consider a process {(Jt,Vt}t≥0 on E×[0,∞, such that {Jt} is a Markov process with finite state space E, and {Vt} has a linear drift ri on intervals where Jt=i and reflection at 0. Such a process arises as a fluid flow model of current interest in telecommunications engineering for the purpose of modeling ATM technology. We compute the mean of the busy period and related first passage times, show that the probability of buffer overflow within a busy cycle is approximately exponential, and give conditioned limit theorems for the busy cycle with implications for quick simulation. Further, various inequalities and approximations for transient behavior are given. Also explicit expressions for the Laplace transform of the busy period are found. Mathematically, the key tool is first passage probabilities and exponential change of measure for Markov additive processes.
Formulation of a Combined Transportation and Inventory Optimization Model with Multiple Time Periods
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G.Krishnakumari,
2016-03-01
Full Text Available Most distribution network design models existing in the literature have focused on minimizing the costs of inventory and transportation. During the analysis of supply chain of currency management problem it is observed that the transportation of currency from various sources to various destinations and the required inventory to be maintained to meet the emerging demands requires formulation of a combined problem. This framework aims to support the coordination of inventory and transportation activities to properly manage the inventory profiles and currency flows between source locations and distribution centers. This paper considers a multi-period inventory and transportation model for a single commodity. The key contribution of this paper is, a mathematical programming formulation of transportation cum inventory problem is proposed and an algorithm for this new formulation as a multi period decision process is intended. A numerical example of currency transportation cum inventory is presented to illustrate the proposed algorithm
Microphysics of Neutron Star Outer Envelopes in the Periodized, Magnetic Thomas-Fermi Model
Engstrom, Tyler A; Owen, Benjamin J; Brannick, James; Hu, Xiaozhe
2014-01-01
Observations of several types of neutron stars indicate surface temperature inhomogeneities. In recent years magneto-thermal simulations have supported the idea that the magnetic field and anisotropic heat conduction play important roles in generating these inhomogeneities. Simulations rely on crustal microphysics input heretofore calculated at the level of a plasma model -- neglecting lattice structure and electron polarizability. We focus on the low density outer envelope, treating both of these elements by a proper periodization of the magnetic Thomas-Fermi model. Our solution method involves a novel domain decomposition and we describe a scalable implementation using \\textit{Hypre}. The method may be seen as a prototype for the general class of problems involving nonlinear charge screening of periodic, quasi-low-dimensionality structures, e.g. liquid crystals. Findings include low density $c'<0$ elastic instabilities for both bcc and fcc lattices, reminiscent of the situation in some light actinides, a...
Unified Modeling of Familial Mediterranean Fever and Cryopyrin Associated Periodic Syndromes
Yasemin Bozkurt; Alper Demir; Burak Erman; Ahmet Gül
2015-01-01
Research Article Unified Modeling of Familial Mediterranean Fever and Cryopyrin Associated Periodic Syndromes Yasemin Bozkurt,1 Alper Demir,1 Burak Erman,1 and Ahmet Gül2 1Computational and Quantitative Biology Lab, Koc University, 34450 Istanbul, Turkey 2Division of Rheumatology,Department of InternalMedicine, Istanbul Faculty ofMedicine, IstanbulUniversity, 34093 Istanbul, Turkey Correspondence should be addressed to Yasemin Bozkurt; Received 18 Sept...
Capella, H M; Lemos, T
2002-01-01
This study addresses the question of epileptogenesis by investigating the effects of carbamazepine (CBZ) on the silent period of the pilocarpine model of epilepsy. Adult Wistar rats were subjected to status epilepticus (SE) induced by pilocarpine and treated with CBZ or saline, i.p, during 56 days. Latency for the first spontaneous seizure, incidence, frequency, and duration of seizures were monitored for seizures and the hippocampal damage. CBZ did not abort the epileptogenesis but minimized the expression of seizures and hippocampal damage.
Information Sharing In Shipbuilding based on the Product State Model
DEFF Research Database (Denmark)
Larsen, Michael Holm
1999-01-01
The paper provides a review of product modelling technologies and the overall architecture for the Product State Model (PSM) environment as a basis for how dynamically updated product data can improve control of production activities. Especially, the paper focuses on the circumstances prevailing...
Integration of satellite fire products into MPI Earth System Model
Khlystova, Iryna G.; Kloster, Silvia
2013-04-01
Fires are the ubiquitous phenomenon affecting all natural biomes. Since the beginning of the satellite Era, fires are being continuously observed from satellites. The most interesting satellite parameter retrieved from satellite measurements is the burned area. Combined with information on biomass available for burning the burned area can be translated into climate relevant carbon emissions from fires into the atmosphere. In this study we integrate observed burned area into a global vegetation model to derive global fire emissions. Global continuous burned area dataset is provided by the Global Fire Emissions Dataset (GFED). GFED products were obtained from MODIS (and pre-MODIS) satellites and are available for the time period of 14 years (1997-2011). This dataset is widely used, well documented and supported by periodical updates containing new features. We integrate the global burned area product into the land model JSBACH, a part of the Earth-System model developed at the Max Plank Institute for Meteorology. The land model JSBACH simulates land biomass in terms of carbon content. Fire is an important disturbance process in the Earth's carbon cycle and affects mainly the carbon stored in vegetation. In the standard JSBACH version fire is represented by process based algorithms. Using the satellite data as an alternative we are targeting better comparability of modeled carbon emissions with independent satellite measurements of atmospheric composition. The structure of burned vegetation inside of a biome can be described as the balance between woody and herbaceous vegetation. GFED provides in addition to the burned area satellite derived information of the tree cover distribution within the burned area. Using this dataset, we can attribute the burned area to the respective simulated herbaceous or woody biomass within the vegetation model. By testing several extreme cases we evaluate the quantitative impact of vegetation balance between woody and herbaceous
Carbon Flux Estimation By Using AGCM-Based Chemistry Transport Model for the Period 1990-2011
Saeki, T.; Patra, P. K.
2014-12-01
Carbon fluxes were estimated for 84 regions (54 lands + 30 oceans) over the globe during the period of 1990-2011. We used (1) the CCSR/NIES/FRCGC AGCM-based Chemistry Transport Model (ACTM), (2) atmospheric CO2 concentrations at 74 sites from GLOBALVIEW-CO2 (2013) data product, (3) Seasonally varying a presubtracted fluxes for atmosphere-ocean exchange (Takahashi et al., 2009), (4) interannually varying a priori fossil fuel fluxes (incl. cement production) from CDIAC global totals and EDGAR4.2 spatial distributions, and (5) 3-hourly terrestrial biosphere fluxes are constructed from the annually balanced CASA and JRA-25 reanalysis meteorology (Y. Niwa, Pers. Comm., 2013). As a result of time-dependent inversions, mean total flux (excluding fossil fuel) for the period 1990-2011 is estimated to be -3.33 GtC/yr, where land (incl. biomass burning and land use change) and ocean absorb an average rate of -1.98 and -1.35 GtC/yr, respectively. The land uptake is mainly due to northern land (-1.57 GtC/yr), while the tropical and southern lands contribute -0.03 and -0.38 GtC/yr, respectively. It is also found that Boreal North America and Boreal Eurasia show negative trends in the estimated fluxes during the analysis period. The global ocean sink has no clear long-term trend in the period. Results with different inversion settings and for other regions will be discussed. Our analysis suggests that no known transport bias in ACTM forward simulation allow us to estimate CO2 fluxes at good accuracy at hemispheric and regional scale. Acknowledgements. This study is supported by the JSPS KANEHI Kiban-A and Global Environment Research Fund (2-1401) of the Ministry of the Environment, Japan.
Batterbee, D C; Sims, N D; Becker, W; Worden, K; Rowson, J
2011-11-01
Non-accidental head injury in infants, or shaken baby syndrome, is a highly controversial and disputed topic. Biomechanical studies often suggest that shaking alone cannot cause the classical symptoms, yet many medical experts believe the contrary. Researchers have turned to finite element modelling for a more detailed understanding of the interactions between the brain, skull, cerebrospinal fluid (CSF), and surrounding tissues. However, the uncertainties in such models are significant; these can arise from theoretical approximations, lack of information, and inherent variability. Consequently, this study presents an uncertainty analysis of a finite element model of a human head subject to shaking. Although the model geometry was greatly simplified, fluid-structure-interaction techniques were used to model the brain, skull, and CSF using a Eulerian mesh formulation with penalty-based coupling. Uncertainty and sensitivity measurements were obtained using Bayesian sensitivity analysis, which is a technique that is relatively new to the engineering community. Uncertainty in nine different model parameters was investigated for two different shaking excitations: sinusoidal translation only, and sinusoidal translation plus rotation about the base of the head. The level and type of sensitivity in the results was found to be highly dependent on the excitation type.
Directory of Open Access Journals (Sweden)
Liliane Moreira Silva
2014-08-01
Full Text Available The objective of the present study was to evaluate the effects of supplementation with detoxified castor meal (DCM in the diet of ewes during pregnancy, partum, and post-partum on the weight development of their offspring and at slaughter. The study included 56 ewes with synchronized estrus that were naturally mated. At the beginning of pregnancy and in post-partum, hepatic and renal function-related parameters and progesterone levels were measured. At slaughter, the proximate composition and fatty acid profile were determined in the loin of ewes. There was no effect of diet on reproductive response after estrus synchronization. At the beginning of pregnancy, albumin and creatinine levels were lower in the DCM group. Supplementation with DCM did not alter the weight or body condition of ewes at partum. However, at weaning, the DCM group showed a higher loin-eye area (LEA in relation to the group fed diets without detoxified castor meal (WDCM. At partum, as well as at weaning, the offspring of the ewes supplemented with DCM had a larger LEA than the WDCM group. In post-partum, levels of glucose, urea, protein, and cholesterol were lower in the DCM group. The return to cyclicity was similar in both groups, with an average of 47 days after partum. At slaughter, neither anatomical and carcass components nor the results of the proximate analysis were affected by the type of diet, except for an increase in heptadecanoic acid in the DCM group. Supplementation with detoxified castor meal in the diet of ewes does not affect lambing, pregnancy, prolificacy, return to cyclicity, milk production, blood biochemical parameters, or carcass characteristics.
Micromechanical modeling of damage in periodic composites using strain gradient plasticity
DEFF Research Database (Denmark)
Azizi, Reza
2012-01-01
Damage evolution at the fiber matrix interface in Metal Matrix Composites (MMCs) is studied using strain gradient theory of plasticity. The study includes the rate independent formulation of energetic strain gradient plasticity for the matrix, purely elastic model for the fiber and cohesive zone...... model under simple shear and transverse uniaxial tension using plane strain and periodic boundary conditions. The result of the overall response curve, effective plastic strain, effective stress and higher order stress distributions are shown. The effect of the material length scale, maximum stress...
Jansen, Peter A; Fiacconi, Chris M; Gibson, Laura C
2010-11-23
The present study develops an explicit and predictive computational model of neonate saccades based on the interaction of several simple mechanisms, including the tendency to fixate towards areas of high contrast, and the decay and recovery of a world-centered contrast representation simulating a low-level inhibition of return mechanism. Emergent properties similar to early visual behaviors develop, including the externality effect (or tendency to focus on external then internal features). The age-associated progression of this effect is modulated by the decay period of the model's contrast representation, where the high-level behavior of either scanning broadly or locally is modulated by a single decay parameter.
Directory of Open Access Journals (Sweden)
Yudhistira Ardana
2016-10-01
Full Text Available This study aimed to analyze the effect of macroeconomic variables on Indonesian Islamic stock index. Macroeconomic variables used is the interest rate of Bank Indonesia (BI-rate, inflation, exchange rate, Bank Indonesia Certificates Sharia (SBIS and world oil prices. The data used in this research is secondary data during the period May 2011 until September 2015 using a model error correction model (ECM where the end result is going to measure the effect of macroeconomic variables on Indonesian Sharia Stock Index in the short term and long term.
The diffusive logistic model with a free boundary in a heterogeneous time-periodic environment
Ding, Weiwei; Peng, Rui; Wei, Lei
2017-09-01
This paper is concerned with a diffusive logistic model with advection and a free boundary in a spatially heterogeneous and time periodic environment. Such a model may be used to describe the spreading of a new or invasive species with the free boundary representing the expanding front. Under more general assumptions on the initial data and the function standing for the intrinsic growth rate of the species, sharp criteria for spreading and vanishing are established, and estimates for spreading speed when spreading occurs are also derived. The obtained results considerably improve and complement the existing ones, especially those of [11,25].
Energy Technology Data Exchange (ETDEWEB)
Venkata Mohan, S.; Mohanakrishna, G.; Ramanaiah, S.V.; Sarma, P.N. [Bioengineering and Environmental Centre, Indian Institute of Chemical Technology, Hyderabad 500007 (India)
2008-01-15
Biohydrogen (H{sub 2}) production with simultaneous wastewater treatment was studied in anaerobic sequencing batch biofilm reactor (AnSBBR) using distillery wastewater as substrate at two operating pH values. Selectively enriched anaerobic mixed consortia sequentially pretreated with repeated heat-shock (100{sup o}C; 2 h) and acid (pH -3.0; 24 h) methods, was used as parent inoculum to startup the bioreactor. The reactor was operated at ambient temperature (28{+-}2 {sup circle} C) with detention time of 24 h in periodic discontinuous batch mode. Experimental data showed the feasibility of hydrogen production along with substrate degradation with distillery wastewater as substrate. The performance of the reactor was found to be dependent on the operating pH. Adopted acidophilic microenvironment (pH 6.0) favored H{sub 2} production (H{sub 2} production rate - 26 mmol H{sub 2}/day; specific H{sub 2} production - 6.98 mol H{sub 2}/kg COD{sub R}-day) over neutral microenvironment (H{sub 2} production rate - 7 mmol H{sub 2}/day; specific H{sub 2} production - 1.63 mol H{sub 2}/kg COD{sub R}-day). However, COD removal efficiency was found to be effective in operated neutral microenvironment (pH 7 - 69.68%; pH 6.0 - 56.25%). The described process documented the dual benefit of renewable energy generation in the form of H{sub 2} with simultaneous wastewater treatment utilizing it as substrate. (author)
A prediction model of vaginal birth after cesarean in the preterm period.
Mardy, Anne H; Ananth, Cande V; Grobman, William A; Gyamfi-Bannerman, Cynthia
2016-10-01
A validated model exists that predicts the probability of vaginal birth after cesarean delivery in patients at term who are undergoing a trial of labor after cesarean delivery. However, a model that predicts the success of a vaginal birth after cesarean delivery in the preterm period has not been developed. We sought to develop and validate a predictive model for vaginal birth after cesarean delivery for women undergoing a trial of labor after cesarean delivery during the preterm period. We performed a secondary analysis of a prospective cohort study designed to evaluate perinatal outcomes in women with a prior cesarean scar. We included women with 1 prior low transverse cesarean delivery undergoing a trial of labor after cesarean delivery with a vertex singleton pregnancy in the preterm period (26-36 weeks). Using multivariable logistic regression modeling, we constructed a predictive model for vaginal birth after cesarean delivery with information known at admission for preterm delivery. Using a 70% to 30% random split of the data, the model was developed in the training data and subsequently confirmed in the validation data. Predictions and area under the curve were based on a 10-fold cross-validated jackknife estimation and based on 1000 bootstrap resampling methods. The adequacy of all models was evaluated based on the Hosmer-Lemeshow goodness-of-fit test. One thousand two hundred ninety-five women met our criteria for analysis. The significant predictors of vaginal birth after cesarean delivery success were chronic hypertension, hypertensive disease of pregnancy (gestational hypertension or preeclampsia), prior vaginal delivery, dilation on cervical examination at admission, prior vaginal birth after cesarean delivery, a recurring indication in a prior cesarean delivery, and induction of labor as well as a 2-way interactions between dilation and hypertensive disease of pregnancy, dilation and diabetes mellitus (pregestational or gestational), and induction
Zied Hajej; Nidhal Rezg; Ali Gharbi
2015-01-01
Due to the expensive production equipment, many manufacturers usually lease production equipment with a warranty period during a finite leasing horizon, rather than purchasing them. The lease contract contains the possibility of obtaining an extended warranty for a given additional cost. In this paper, based on the forecasting production/maintenance optimization problem, we develop a mathematical model to study the lease contract with basic and extended warranty based on win-win relationship ...
Xie, Chunyan; Wang, Qinhua; Wang, Jing; Tan, Bie; Fan, Zhiyong; Deng, Ze-yuan; Wu, Xin; Yin, Yulong
2016-02-19
The liver glucose metabolism, supplying sufficient energy for glucose-dependent tissues, is important in suckling or weaned animals, although there are few studies with piglet model. To better understand the development of glucose metabolism in the piglets during suckling period and early weaning period, we determined the hepatic glycogen content, and investigated the relative protein expression of key enzymes of glucogenesis (GNG) and mRNA levels of some glucose metabolism-related genes. During suckling period, the protein level of G6Pase in the liver of suckling piglets progressively declined with day of age compared with that of newborn piglets (at 1 day of age), whereas the PEPCK level stabilized until day 21 of age, indicating that hepatic GNG capacity gradually weakened in suckling piglets. The synthesis of hepatic glycogen, which was consistent with the fluctuation of glycolytic key genes PFKL and PKLR that gradually decreased after birth and was more or less steady during latter suckling period, although both the mRNA levels of GCK and key glucose transporter GLUT2 presented uptrend in suckling piglets. However, early weaning significantly suppressed the hepatic GNG in the weaned piglets, especially at d 3-5 of weaning period, then gradually recovered at d 7 of weaning period. Meanwhile, PFKL, PKLR and GLUT2 showed the similar trend during weaning period. On the contrast, the hepatic glycogen reached the maximum value when the G6Pase and PEPCK protein expression were at the lowest level, although the GCK level maintained increasing through 7 days of weaning period. Altogether, our study provides evidence that hepatic GNG and glycolysis in newborn piglets were more active than other days during suckling period, and early weaning could significantly suppressed glucose metabolism in liver, but this inhibition would progressively recover at day 7 after weaning.
Pion production model - connection between dynamics and quark models
Energy Technology Data Exchange (ETDEWEB)
Lee, T.-S. H.; Sato, T.
2000-05-17
The authors discuss the difficulties in testing the hadron models by using the N{sup *} parameters extracted from the empirical amplitude analyses of the {pi}N and {gamma}N reaction data. As an alternative or perhaps a more advantageous approach, they present a Hamiltonian formulation that can relate the pion production dynamics and the constituent quark models of N{sup *} structure. The application of the approach in investigating the {Delta} and N{sup *}(S{sub 11}) excitations is reviewed. It is found that while the {Delta} excitation can be described satisfactory, the {pi}N scattering in S{sub 11} channel can not be described by the constituent quark models based on either the one-gluon-exchange or one-meson-exchange mechanisms. A phenomenological quark-quark potential has been constructed to reproduce the S{sub 11} amplitude.
Directory of Open Access Journals (Sweden)
Evgeniya V. SINCHINA
2016-01-01
Full Text Available The relevance of this article due to the importance of studying the history of the agrarian sector of Russia's regions, which today plays a significant role in the economy. Before the revolution the Russian empire was an agrarian-industrial state, a huge part of the population was engaged in agriculture, and the leading role in the trade, both domestic and international, took the grain. However, it began to gain momentum in the market and agricultural crops, nongrain. The presented article is devoted to the production of non-grain agricultural Stavropol, which has increased significantly in the post-reform period (1861‒1917. The author considers the main nongrain production industry Stavropol province, characterized by varying degrees of marketability, but showing the strengthening of agricultural specialization, which in this period was typical for many regions of the Russian Empire. Information on the development of tobacco, wine, flax growing, horticulture, and gardening illustrate the increase in specialization of agriculture Stavropol province. Presents statistical data, many of which are based on previously attracted by archival documents that characterize degree of development of non-grain agricultural production of this region. The importance of non-grain specialization for agricultural technology, but it is as certain cultures impacted the crop rotation, which in the period of study required innovations in the power of soil depletion due to neglect them human. The author also touched upon aspect of the formation of a local processing industry (for example, wine, distilling, vegetable oil, etc.. In addition, for the Stavropol region was characterized by a special agricultural and fishery ‒ sericulture, are profitable and promising business.
A Partial Backlogging Inventory Model with Time-Varying Demand During Shortage Period
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Chen Mang
2010-11-01
Full Text Available Harris’s classic square root economic order quantity (EOQ model forms the basis for many other models that relax one or more of its assumptions. A key assumption of the basic EOQ model is that stockouts are not permitted. Due to the excess demands, stock-out situations may arise occasionally. Sometimes, shortages are permitted and they are backordered and satisfied in the very next replenishment. Therefore the objective of this paper is to develop a partial backlogging inventory model, and proposes a new algorithm to minimize the total cost, at the same time also propose the prediction method and algorithm of ordering period. Finally, a practical example of the numerical analysis is given.
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Alireza Rashidi Komijan
2017-07-01
Full Text Available The well-known Vehicle Routing Problem (VRP is to find proper sequence of routes in order to minimize transportation costs. In this paper, a mixed-integer programming model is presented for a food distributer company and the model outputs are to determine the optimal routes and amount of pickup and delivery. In the objective function, the costs of transportation, holding, tardiness and earliness are considered simultaneously. The proposed model with respect to real conditions is multi-period and has two different time periods: one for dispatching vehicles to customers and suppliers and the other for receiving customers’ orders. Time window and split pickup and delivery are considered for perishable products. The proposed model is nonlinear and will be linearized using exact techniques. At the end, model is solved using GAMS and the sensitivity analysis is performed. The results indicate that the trend of changes in holding and transportation costs in compared to tardiness and earliness costs are closed together and are not so sensitive to demand changes.
A Knowledge Model System for Wheat Production Management
Institute of Scientific and Technical Information of China (English)
ZHU Yan; CAO Wei-Xing; DAI Ting-Bo; TIAN Yong-Chao; YAO Xia
2007-01-01
A knowledge model with temporal and spatial characteristics for the quantitative design of a cultural pattern in wheat production,using systems analysis and dynamic modeling techniques,was developed for wheat management,as a decision-making tool in digital farming.The fundamental relationships and algorithms of wheat growth indices and management criteria to cultivars,ecological environments,and production levels were derived from the existing literature and research data to establish a knowledge model system for quantitative wheat management using Visual C++.The system designed a cultural management plan for general management guidelines and crop regulation indices for timecourse control criteria during the wheat-growing period.The cultural management plan module included submodels to determine target grain yield and quality,cultivar choice,sowing date,population density,sowing rate,fertilization strategy,and Water management,whereas the crop regulation indices module included submodels for suitable development stages,dynamic growth indices,source-sink indices,and nutrient indices.Evaluation of the knowledge model by design studies on the basis of data sets of different eco-sites,cultivars,and soil types indicated a favorable performance of the model system in recommending growth indices and management criteria under diverse conditions.Practical application of the knowledge model system in comparative field experiments produced yield gains of 2.4%to 16.5%.Thus,the presented knowledge model system overcame some of the difficulties of the traditional wheat management patterns and expert systems,and laid a foundation for facilitating the digitization of wheat management.
Modelling preparation and consumption of pork products
DEFF Research Database (Denmark)
Swart, Arno; Nauta, Maarten; Evers, Eric
This poster describes the retail and consumer phase of the EFSA Salmonella in Pork QMRA (Quantitative Microbiological Risk Assessment, funded under an Article 36 grant to support the scientific opinion required by EFS). The food chain is modelled from retail to ingestion by the consumer. Three...... types of pork are considered: minced meat, pork cuts and dry cured sausages. This particular choice was made because each product represents a clear distinct hazard. Pork cuts are usually cooked well, but there is a chance of cross contamination during cutting and handling of the meat. Minced meat...... is thoroughly mixed, and Salmonellae may be present in the interior of hamburger patties, undercooking may occur, and Salmonellae may survive. Dry cured sausages, including all variations therein like chorizo, salami, etc., are eaten uncooked. Food preparation habits are highly variable and accurate data...
Impedance Matching for Discrete, Periodic Media and Application to Two-Scale Wave Propagation Models
Thirunavukkarasu, Senganal
This dissertation introduces the idea of an equivalent continuous medium (ECM) that has the same impedance as that of an unbounded discrete periodic medium. Contrary to existing knowledge, we constructively show that it is indeed possible to achieve perfect matching for periodic and discrete media. We present analytical results relating the propagation characteristics of periodic media and the corresponding ECM, leading to the development of numerical methods for wave propagation in these media. In this dissertation, we present the main idea of ECM and apply it, with mixed results, to seemingly different problems requiring effective numerical methods for modeling wave propagation in unbounded media. An immediate application of ECM is in developing absorbing boundary conditions (ABCs) for wave propagation in unbounded discrete media. Using the idea of ECM, and building on class of continuous ABCs called perfectly matched discrete layers (PMDL), we propose a new class of discrete ABCs called discrete PMDL and develop frequency domain formulations that are shown to be superior to continuous ABCs. Another application that is explored in this dissertation is the design of interface conditions for concurrent coupling of two-scale wave propagation models, e.g. Atomistic-to-Continuum (AtC) coupling. We propose a domain-decomposition (DD) approach and develop accurate interface conditions that are critical for the concurrent coupling of the two-scale models. It turns out that time-domain discrete ABCs are key to the the accuracy of these interface conditions. Since discrete PMDL is well-posed and accurate for the model problem, we build on it to propose an efficient and accurate interface condition for two-scale wave propagation models. Although many open problems remain with respect to implementation, we believe that the proposed DD based approach is a good first step towards achieving efficient coupling of two-scale wave propagation models. Time-domain discrete PMDL can
Periodicity in a Conceptual Model of Glacial Cycles in the Absence of Milankovitch Forcing
Hahn, J.; Walsh, J.; Widiasih, E.; McGehee, R.
2015-12-01
Previously, McGehee and Widiasih coupled Budyko's Energy Balance Model with dynamics of a latitudinal ice-line incorporating the albedo feedback effect. They reduced this model to a two-dimensional equation of global mean temperature and a latitudinal ice-line. With this conceptual model, we now include dynamics of the ablation and accumulation of ice, to form a three-dimensional system that partitions the regions of the Earth latitudinally into an accumulation zone, ablation zone, and ice-free zone. Motivated by the findings of Abe-Ouchi et al that the fast retreat of ice-sheets is due to an increased rate of ablation via the effects of delayed isostatic rebound, we incorporate a simple switching mechanism to the model which increases the rate of ablation during periods of glacial retreat. This forms a discontinuous system of the Earth's temperature and ice-volume in which we find a stable periodic orbit. This can be interpreted as a intrinsic cycling of the Earth's climate in the absence of Milankovitch forcing.
A New Model of Roche Lobe Overflow for Short-period Gaseous Planets and Binary Stars
Jackson, Brian; Arras, Phil; Penev, Kaloyan; Peacock, Sarah; Marchant, Pablo
2017-02-01
Some close-in gaseous exoplanets are nearly in Roche lobe contact, and previous studies show that tidal decay can drive hot Jupiters into contact during the main sequence of their host stars. Improving on a previous model, we present a revised model for mass transfer in a semidetached binary system that incorporates an extended atmosphere around the donor and allows for an arbitrary mass ratio. We apply this new formalism to hypothetical, confirmed, and candidate planetary systems to estimate mass-loss rates and compare with models of evaporative mass loss. Overflow may be significant for hot Neptunes out to periods of ∼2 days, while for hot Jupiters, it may only be important inward of 0.5 days. We find that CoRoT-24 b may be losing mass at a rate of more than an Earth mass in a gigayear. The hot Jupiter WASP-12 b may lose an Earth mass in a megayear, while the putative planet PTFO8-8695 orbiting a T Tauri star might shed its atmosphere in a few megayears. We point out that the orbital expansion that can accompany mass transfer may be less effective than previously considered because the gas accreted by the host star removes some of the angular momentum from the orbit, but simple scaling arguments suggest that the Roche lobe overflow might remain stable. Consequently, the recently discovered small planets in ultrashort periods (model presented here has been incorporated into Modules for Experiments in Stellar Astrophysics (MESA).
A periodic charge-dipole electrostatic model: parametrization for silver slabs.
Bodrenko, I V; Sierka, M; Fabiano, E; Della Sala, F
2012-10-07
We present an extension of the charge-dipole model for the description of periodic systems. This periodic charge-dipole electrostatic model (PCDEM) allows one to describe the linear response of periodic structures in terms of charge- and dipole-type gaussian basis functions. The long-range electrostatic interaction is efficiently described by means of the continuous fast multipole method. As a first application, the PCDEM method is applied to describe the polarizability of silver slabs. We find that for a correct description of the polarizability of the slabs both charges and dipoles are required. However a continuum set of parametrizations, i.e., different values of the width of charge- and dipole-type gaussians, leads to an equivalent and accurate description of the slabs polarizability but a completely unphysical description of induced charge-density inside the slab. We introduced the integral squared density measure which allows one to obtain a unique parametrization which accurately describes both the polarizability and the induced density profile inside the slab. Finally the limits of the electrostatic approximations are also pointed out.
Bakst, M R
1988-07-01
The onset of egg production (mean 18.3 days after the onset of photostimulation) and the rate of egg production (flock averaged 4.9 eggs per bird per week for the first 8 weeks of egg production) were not affected by 5 days of twice daily oviduct eversion ('venting') in the pre-laying period when compared to unvented controls. After the onset of photostimulation, pre-laying hens were inseminated twice daily on Days 12 to 16 with 3 microliter semen containing 15 x 10(6) spermatozoa, and compared with groups of hens inseminated once daily on Days 15 and 16 with 15 microliters semen containing 75 x 10(6) spermatozoa or 41 microliter semen containing 200 x 10(6) spermatozoa. Fertility remained high for the first 5 weeks of egg production. However, by Week 6 the fertility of the hens receiving frequent low doses of semen dropped significantly below that of the others, which suggests that multiple inseminations with a low semen volume containing relatively low numbers of spermatozoa does not lead to an increase in the efficacy of sperm transport and storage in the oviduct.
Production TTR modeling and dynamic buckling analysis
Institute of Scientific and Technical Information of China (English)
Hugh Liu; John Wei; Edward Huang
2013-01-01
In a typical tension leg platform (TLP) design,the top tension factor (TTF),measuring the top tension of a top tensioned riser (TTR) relative to its submerged weight in water,is one of the most important design parameters that has to be specified properly.While a very small TTF may lead to excessive vortex induced vibration (ⅤⅣ),clashing issues and possible compression close to seafloor,an unnecessarily high TTF may translate into excessive riser cost and vessel payload,and even has impacts on the TLP sizing and design in general.In the process of a production TTR design,it is found that its outer casing can be subjected to compression in a worst-case scenario with some extreme metocean and hardware conditions.The present paper shows how finite element analysis (FEA) models using beam elements and two different software packages (Flexcom and ABAQUS) are constructed to simulate the TTR properly,and especially the pipe-in-pipe effects.An ABAQUS model with hybrid elements (beam elements globally + shell elements locally) can be used to investigate how the outer casing behaves under compression.It is shown for the specified TTR design,even with its outer casing being under some local compression in the worst-case scenario,dynamic buckling would not occur; therefore the TTR design is adequate.
Directory of Open Access Journals (Sweden)
Morgana Pizzolato
2005-08-01
Full Text Available Este artigo documenta os resultados da aplicação de um método para otimização de aspectos da qualidade e vida útil para posterior definição do prazo de garantia de produtos que não falham, mas degradam até uma condição considerada aceitável. O método de otimização é composto pelas seguintes etapas: i caracterização do problema; ii planejamento e execução dos experimentos; iii modelagem das variáveis de resposta; iv otimização; e v modelagem da vida útil e definição do prazo de garantia. As etapas metodológicas contemplam o uso de QFD (Desdobramento da Função Qualidade, de Projeto de Experimentos, modelos de regressão de ensaios acelerados e modelos de degradação. Para a otimização e determinação do prazo de garantia, é apresentado um procedimento que utiliza uma seqüência de passos em que ferramentas estatísticas, como análise de regressão e modelagem de dados de degradação, são empregadas. Somado a isso, são utilizados procedimentos de avaliação sensorial para avaliar os níveis de degradação das amostras do produto. O método é aplicado em um produto utilizado na criação de animais.This paper discusses the results of the application of a method to optimize the quality characteristics and service life of products that degrade rather than fail in order to determine the warranty period of such products. The optimization method consists of the following steps: i characterization of the problem; ii planning and execution of experiments; iii modeling of response variables; iv optimization; and v modeling of the product's service life and definition of its warranty period. The method involves the joint use of QFD (Quality Function Deployment, Experimental Design, and modeling of accelerated degradation tests through regression analysis. A new procedure is presented to determine and optimize the warranty period of products subject to degradation, based on the sensorial analysis of sample products
Model of inventory replenishment in periodic review accounting for the occurrence of shortages
Directory of Open Access Journals (Sweden)
Stanisław Krzyżaniak
2014-03-01
Full Text Available Background: Despite the development of alternative concepts of goods flow management, the inventory management under conditions of random variations of demand is still an important issue, both from the point of view of inventory keeping and replenishment costs and the service level measured as the level of inventory availability. There is a number of inventory replenishment systems used in these conditions, but they are mostly developments of two basic systems: reorder point-based and periodic review-based. The paper deals with the latter system. Numerous researches indicate the need to improve the classical models describing that system, the reason being mainly the necessity to adapt the model better to the actual conditions. This allows a correct selection of parameters that control the used inventory replenishment system and - as a result - to obtain expected economic effects. Methods: This research aimed at building a model of the periodic review system to reflect the relations (observed during simulation tests between the volume of inventory shortages and the degree of accounting for so-called deferred demand, and the service level expressed as the probability of satisfying the demand in the review and the inventory replenishment cycle. The following model building and testing method has been applied: numerical simulation of inventory replenishment - detailed analysis of simulation results - construction of the model taking into account the regularities observed during the simulations - determination of principles of solving the system of relations creating the model - verification of the results obtained from the model using the results from simulation. Results: Presented are selected results of calculations based on classical formulas and using the developed model, which describe the relations between the service level and the parameters controlling the discussed inventory replenishment system. The results are compared to the simulation
Groundwater flow modelling of periods with periglacial and glacial climate conditions - Forsmark
Energy Technology Data Exchange (ETDEWEB)
Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Follin, Sven (SF GeoLogic AB, Taeby (Sweden)); Zugec, Nada (Bergab, Stockholm (Sweden))
2010-12-15
As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. Hydraulic-mechanical (H-M) issues are also handled but no coupled flow modelling is done. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle for subsequent use in safety assessment applications within SKB's project SR-Site. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 19,000 years. The simulation results comprise residual fluid pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance, the speed of the ice sheet margin, the bedrock hydraulic and transport properties, the temperature at the ice-subsurface interface close to the ice sheet margin, and the initial hydrochemical conditions.
Developing engineering processes through integrated modelling of product and process
DEFF Research Database (Denmark)
Nielsen, Jeppe Bjerrum; Hvam, Lars
2012-01-01
This article aims at developing an operational tool for integrated modelling of product assortments and engineering processes in companies making customer specific products. Integrating a product model in the design of engineering processes will provide a deeper understanding of the engineering...... activities as well as insight into how product features affect the engineering processes. The article suggests possible ways of integrating models of products with models of engineering processes. The models have been tested and further developed in an action research study carried out in collaboration...
Elmorjani, K; Thiévin, M; Michon, T; Popineau, Y; Hallet, J N; Guéguen, J
1997-10-09
In order to optimise new polypeptide based biomaterials, we developed a procedure for producing homoblock polypeptides using recombinant DNA technology. Synthetic genes encoding periodic polypeptides modelled on the consensus sequence of wheat gliadins (a family of wheat storage proteins) were devised to be expressed in Escherichia coli. The construction strategy followed allows the construction of three genes encoding 8, 16, and 32 copies of the PQQPY module. The optimal expression conditions in the enterobacteria were established and a convenient purification procedure was shown to be useful in recovery of sizable amounts of strictly periodic polypeptides. The identities of the synthesized polypeptides were assessed using positive cross reactions to antibodies raised against a synthetic decapeptide (PQQPYPQQPA) and amino acid composition was determined as well.
Model independent X-ray standing wave analysis of periodic multilayer structures
Yakunin, S N; Chuev, M A; Pashaev, E M; Zoethout, E; Louis, E; van de Kruijs, R W E; Seregin, S Yu; Subbotin, I A; Novikov, D V; Bijkerk, F; Kovalchuk, M V
2013-01-01
We present a model independent approach for the reconstruction of the atomic concentration profile in a nanoscale layered structure, as measured using the X-ray fluorescence yield modulated by an X-ray standing wave (XSW). The approach is based on the direct regularized solution of the system of linear equations that characterizes the fluorescence yield. The suggested technique was optimized for, but not limited to, the analysis of periodic layered structures where the XSW is formed under Bragg conditions. The developed approach was applied to the reconstruction of the atomic concentration profiles for LaN/BN multilayers with 50 periods of 35 A thick layers. The object is especially difficult to analyse with traditional methods, as the estimated thickness of the interface region between the constituent materials is comparable to the individual layer thicknesses. However, using the suggested technique it was possible to reconstruct the La atomic profile, showing that the La atoms stay localized within the LaN ...
Modelling production system architectures in the early phases of product development
DEFF Research Database (Denmark)
Guðlaugsson, Tómas Vignir; Martin Ravn, Poul; Mortensen, Niels Henrik;
2016-01-01
on – leading to an improved basis for prioritizing activities in the project. Requirements for the contents of the framework are presented, and literature on production and system models is reviewed. The production system architecture modelling framework is founded on methods and approaches in literature......This article suggests a framework for modelling a production system architecture in the early phases of product development.The challenge in these phases is that the products to be produced are not completely defined and yet decisions need to be made early in the process on what investments...... and adjusted to fit the modelling requirements of a production system architecture at an early phase of development. The production system architecture models capture and describe the structure, capabilities and expansions of the production system architecture underdevelopment. The production system...
General model selection estimation of a periodic regression with a Gaussian noise
Konev, Victor; 10.1007/s10463-008-0193-1
2010-01-01
This paper considers the problem of estimating a periodic function in a continuous time regression model with an additive stationary gaussian noise having unknown correlation function. A general model selection procedure on the basis of arbitrary projective estimates, which does not need the knowledge of the noise correlation function, is proposed. A non-asymptotic upper bound for quadratic risk (oracle inequality) has been derived under mild conditions on the noise. For the Ornstein-Uhlenbeck noise the risk upper bound is shown to be uniform in the nuisance parameter. In the case of gaussian white noise the constructed procedure has some advantages as compared with the procedure based on the least squares estimates (LSE). The asymptotic minimaxity of the estimates has been proved. The proposed model selection scheme is extended also to the estimation problem based on the discrete data applicably to the situation when high frequency sampling can not be provided.
A Modelling of Normal and Abnormal EMG Silent Period Generation of Masseter Muscle
Energy Technology Data Exchange (ETDEWEB)
Kim, T.H.; Jeon, C.I. [University Of Seoul, Seoul (Korea); Lee, S.H. [Induk Institute of Technology, Seoul (Korea)
2003-02-01
This paper proposes a model of SP(silent period) generation in masseter muscle by means of computer simulation. The model is based on the anatomical and physiological properties of trigeminal nervous system. In determining the SP generation pathway, evoked SPs of masseter muscle after mechanical stimulation to the chin are divided into normal and abnormal group. Normal SP is produced by the activation of mechanoreceptors in periodontal ligament. The activation of nociceptors contributes to the latter part of normal SP, abnormal extended SP is produced. As a result, the EMG signal generated by a proposed SP generation model is similar to both real EMG signal including normal SP and abnormal extended SP with TMJ patients. The result of this study have shown differences of SP generation mechanism between subjects both with and without TMJ dysfunction. (author). 21 refs., 12 figs., 1 tab.
Integrating geological archives and climate models for the mid-Pliocene warm period
Haywood, Alan M.; Dowsett, Harry J.; Dolan, Aisling M.
2016-02-01
The mid-Pliocene Warm Period (mPWP) offers an opportunity to understand a warmer-than-present world and assess the predictive ability of numerical climate models. Environmental reconstruction and climate modelling are crucial for understanding the mPWP, and the synergy of these two, often disparate, fields has proven essential in confirming features of the past and in turn building confidence in projections of the future. The continual development of methodologies to better facilitate environmental synthesis and data/model comparison is essential, with recent work demonstrating that time-specific (time-slice) syntheses represent the next logical step in exploring climate change during the mPWP and realizing its potential as a test bed for understanding future climate change.
Universal scaling in the Knight-shift anomaly of the doped periodic Anderson model
Jiang, M.; Yang, Yi-feng
2017-06-01
We report a dynamical cluster approximation investigation of the doped periodic Anderson model to explain the universal scaling in the Knight-shift anomaly predicted by the phenomenological two-fluid model and confirmed in many heavy-fermion compounds. We calculate the quantitative evolution of the orbital-dependent magnetic susceptibility and reproduce correctly the two-fluid prediction in a large range of doping and hybridization. Our results confirm the presence of a temperature/energy scale T* for the universal scaling and show distinctive behaviors of the Knight-shift anomaly in response to other "orders" at low temperatures. However, comparison with the temperature evolution of the calculated resistivity and quasiparticle spectral peak indicates a different characteristic temperature from T*, in contradiction with the experimental observation in CeCoIn5 and other compounds. This reveals a missing piece in the current model calculations in explaining the two-fluid phenomenology.
An asymmetric dimer in a periodic potential: a minimal model for friction of graphene flakes
Hens, Remco; Fasolino, Annalisa
2016-07-01
We discuss the friction and motion of a model of a dimer with asymmetric interactions with a substrate potential. Starting from the consideration that a rigid dimer with spacing equal to half of the period of the potential has exactly zero static friction like the infinite incommensurate Frenkel Kontorova model, we show how stick-slip behaviour and friction arise as a function of asymmetry. We argue that this model can yield a simple yet insightful description of the frictional behaviour of graphene flakes on graphite and of superlubricity. The results can also be of interest for diatomic molecules on surfaces. Supplementary material in the form of three mp4 files available from the Journal web page at http://dx.doi.org/10.1140/epjb/e2016-70273-5
Mathematical Modeling and Analysis of Classified Marketing of Agricultural Products
Institute of Scientific and Technical Information of China (English)
Fengying; WANG
2014-01-01
Classified marketing of agricultural products was analyzed using the Logistic Regression Model. This method can take full advantage of information in agricultural product database,to find factors influencing best selling degree of agricultural products,and make quantitative analysis accordingly. Using this model,it is also able to predict sales of agricultural products,and provide reference for mapping out individualized sales strategy for popularizing agricultural products.
Very long-period GPS waveforms. What can GPS bring to Earth seismic velocity models?
Kelevitz, K.; Houlie, N.; Nissen-Meyer, T.; Boschi, L.; Giardini, D.; Rothacher, M.
2014-12-01
It is now admitted that high rate GPS observations can provide reliable surface displacement waveforms. For long-period (T > 5s) transients, it was shown that GPS and seismometer (STS-1) displacements are in agreement at least for vertical component [Houlié et al., 2011]. We propose here to supplement existing long-period seismic networks with high rate (>= 1Hz) GPS data in order to improve the resolution of global seismic velocity models. We aim at extending the use of GPS measurements beyond the range of STS-1 in the low frequency end (T>1000s). We present the results of the processing of 1Hz GPS records of the Hokkaido, Sumatra and Tohoku earthquakes (25th of September, 2003, Mw = 8.3; 26th of December, 2004, Mw = 8.9; 11th of March, 2011, Mw = 9.1, respectively). 3D waveforms phase time-series have been used to recover the ground motion histories at the GPS sites. Through the better resolution of inversion of the GPS phase observations, we determine displacement waveforms of periods ranging from 30 seconds to 1300 seconds for a selection of sites. We compare inverted GPS waveforms with STS-1 waveforms, superconducting gravity waveforms and synthetic waveforms computed using 3D global wave propagation with SPECFEM. We find that the GPS waveforms are in agreement with the SPECFEM synthetic data and are able to fill the period-gap between the broadband seismometer STS-1 data and the normal mode period range detected by the superconducting gravimeters. References: Houlié, N., G. Occhipinti, T. Blanchard, N. Shapiro, P. Lognonne, and M. Murakami (2011), New approach to detect seismic surface waves in 1Hz-sampled GPS time series, Scientific reports, 1, 44.
Directory of Open Access Journals (Sweden)
Mohammadhadi Jazini
2013-12-01
Full Text Available Pichia pastoris is an attractive candidate platform for recombinant protein production. Dissolved oxygen is one of the most important factors in the cultivation of P. pastoris. However, the effect of oxygen on triggering productivity led to ambivalent results. In our earlier work, a two-compartment system, consisting of a single reactor coupled with a plug flow reactor (PFR, has been proposed as a tool to improve protein quantity and quality. The goal of this work was to investigate the effects of frequency (the residence time of broth in the PFR and amplitude (the dissolved oxygen level in the reactor of the stress on productivity, titer and physiology. A recombinant P. pastoris strain, which expressed horseradish peroxidase, was used as the model system. Thirteen experiments were performed. Multivariate data analysis was done and the results showed that the residence time did not influence titer, productivity and physiology over the range of residence time studied while dissolved oxygen influenced titer and specific productivity in a quadratic function. In other words, an intermediate level of dissolved oxygen (25% showed the highest specific productivity and titter, irrespective of the residence time in the PFR. In turn, the variation of the residence time and dissolved oxygen did not influence growth physiology, as quantified in biomass and carbon dioxide yields.
Mann, S; Yepes, F A Leal; Overton, T R; Wakshlag, J J; Lock, A L; Ryan, C M; Nydam, D V
2015-05-01
The objective was to investigate the effect of different dry cow feeding strategies on the degree of ketonemia postpartum. Epidemiologic studies provide evidence of an association between elevated β-hydroxybutyrate (BHBA) concentrations in postpartum dairy cows and a decreased risk for reproductive success as well as increased risk for several diseases in early lactation, such as displacement of the abomasum and metritis. The plane of energy fed to cows in the prepartum period has been shown to influence ketogenesis and the degree of negative energy balance postpartum. Our hypothesis was that a high-fiber, controlled-energy diet (C) fed during the dry period would lead to a lower degree of hyperketonemia in the first weeks postpartum compared with either a high-energy diet (H), or a diet where an intermediate level of energy would only be fed in the close-up period (starting at 28d before expected parturition), following the same controlled-energy diet in the far-off period. Hyperketonemia in this study was defined as a blood BHBA concentration of ≥1.2mmol/L. Holstein cows (n=84) entering parity 2 or greater were enrolled using a randomized block design and housed in individual tiestalls. All treatment diets were fed for ad libitum intake and contained monensin. Cows received the same fresh cow ration after calving. Blood samples were obtained 3 times weekly before and after calving and analyzed for BHBA and nonesterified fatty acids (NEFA). Milk components, production, and dry matter intake were recorded and energy balance was calculated. Repeated measures ANOVA was conducted for the outcomes dry matter intake, energy balance, BHBA and NEFA concentrations, milk and energy-corrected milk yield, as well as milk composition. Predicted energy balance tended to be less negative postpartum in group C and cows in this group had fewer episodes of hyperketonemia compared with both the intermediate group and group H in the first 3 wk after calving. Postpartum BHBA and
Kaukonen, Eija; Norring, Marianna; Valros, Anna
2016-12-01
Foot pad dermatitis and hock burn lesions are a form of contact dermatitis, a condition affecting skin areas in contact with unsuitable or irritating material. Contact dermatitis is a common problem, reducing the welfare of broilers, and is believed to also affect broiler breeders. However, there is very little research on contact dermatitis in breeders. This study followed the severity of foot pad lesions in broiler breeders throughout the production period. At slaughter the presence of hock burns and breast blisters was also determined. In addition, changes in litter condition over time and the impact of litter quality on foot pads were evaluated. The study was performed on 10 broiler breeder farms, including altogether 18 flocks. Foot pads of 100 hens per flock were assessed at the end of rearing period, three times during the production period, and at slaughter. Foot pad and hock lesions, as well as litter condition were scored on a 5-point scale. Litter quality was evaluated as pH, moisture and ammonia content. The condition of foot pads deteriorated towards slaughter age, with the occurrence of severe lesions reaching a maximum of 64% on average at slaughter. Hock lesions and breast blisters were rare. The litter layer became drier over time. Although poorer litter condition and wetness influenced foot pad health negatively, the effect on severe lesions was not significant. We also observed a negative effect on foot pad condition of larger slat areas. In conclusion, maintaining good litter quality alone is not enough to ensure healthy foot pads in broiler breeders.
A Conceptual Model for Production Leveling (Heijunka) Implementation in Batch Production Systems
De Araujo, Luciano Fonseca; De Queiroz, Abelardo Alves
2010-01-01
International audience; This paper explains an implementation model for a new method for Production Leveling designed for batch production system. The main structure of this model is grounded on three constructs: traditional framework for Operations Planning, Lean Manufacturing concepts for Production Leveling and case study guidelines. By combining the first and second construct, a framework for Production Leveling has been developed for batch production systems. Then, case study guidelines ...
Modelling and using product architectures in mechatronic product development
DEFF Research Database (Denmark)
Bruun, Hans Peter Lomholt; Mortensen, Niels Henrik
, experiences by using the architecture representation in a mechatronic development project, and the scope of using the architecture model as a skeleton for a data structure in a PLM system. The fundamental idea for planning and modeling holistic architectures is that an improved understanding of the whole...
Energy Technology Data Exchange (ETDEWEB)
Montoya, M.L. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik
1999-07-01
Climatic conditions during the lst interglacial (125,000 years before present) are investigated with two climate models of different complexity: The atmosphere-ocean general circulation model ECHAM-1/LSG and the climate system model of intermediate complexity CLIMBER-2. In particular the role of vegetation at the last interglacial maximum, and its importance for a consistent simulation of the Mid-Holocene climate, has been investigated (EU project ASPEN: Air-Sea Wave Processes in Climate Change Models). Comparison of the results of the two models reveals a broad agreement in most large-scale features. Nevertheless, discrepancies are also detected. Essentially, the models differ in their ocean circulation responses. Profiting of the fast turnaround time of CLIMBER-2, a number of sensitivity experiments have been performed to try to explain the possible reasons for these differences, and to analyze additional effects not included in the previous simulations. In particular, the role of vegetation at the last interglacial maximum has been investigated. Comparison of the simulated responses against CLIMAP reconstructed SSTs for Marine Isotope Stage 5e shows a satisfactory agreement within the data uncertainties. (orig.) [German] Die klimatischen Bedingungen waehrend der letzten interglazialen Periode (vor 125 000 Jahren) werden anhand zweier Klimamodelle unterschiedlicher Komplexitaet untersucht: Dem Ozean-Atmosphaere gekoppelten allgemeinen Zirkulationsmodell ECHAM-1/LSG und dem Klimasystemmodell mittlerer Komplexitaet CLIMBER-2. Inbesondere wurde die Rolle der Vegetation in der letzten interglazialen Periode und ihre Bedeutung fuer eine konsistente Simulation des mittelholozaenischen Klimas untersucht (EU-Projekt ASPEN: Air-Sea Wave Processes in Climate Change Models - 'Klimavariationen in historischen Zeiten'). Der Vergleich der Ergebnisse beider Modelle zeigt eine gute Uebereinstimmung der meisten der grossskaligen Eigenschaften, allerdings zeigen sich
A Model for (Quasi-)Periodic Multi-wavelength Photometric Variability in Young Stellar Objects
Kesseli, Aurora Y; Wood, Kenneth; Whitney, Barbara A; Hillenbrand, L A; Gregory, Scott G; Stauffer, J R; Morales-Calderon, M; Rebull, L; Alencar, S H P
2016-01-01
We present radiation transfer models of rotating young stellar objects (YSOs) with hotspots in their atmospheres, inner disk warps and other 3-D effects in the nearby circumstellar environment. Our models are based on the geometry expected from the magneto-accretion theory, where material moving inward in the disk flows along magnetic field lines to the star and creates stellar hotspots upon impact. Due to rotation of the star and magnetosphere, the disk is variably illuminated. We compare our model light curves to data from the Spitzer YSOVAR project (Morales-Calderon et al. 2014, Cody et al. 2014) to determine if these processes can explain the variability observed at optical and mid-infrared wavelengths in young stars. We focus on those variables exhibiting "dipper" behavior that may be periodic, quasi-periodic, or aperiodic. We find that the stellar hotspot size and temperature affects the optical and near-infrared light curves, while the shape and vertical extent of the inner disk warp affects the mid-IR...
Application of the Periodic Average System Model in Dam Deformation Analysis
Directory of Open Access Journals (Sweden)
Yueqian Shen
2015-01-01
Full Text Available Dams are among the most important hydraulic engineering facilities used for water supply, flood control, and hydroelectric power. Monitoring of dams is crucial since deformation might have occurred. How to obtain the deformation information and then judge the safe conditions is the key and difficult problem in dam deformation monitoring field. This paper proposes the periodic average system model and creates the concept of “settlement activity” based on the dam deformation issue. Long-term deformation monitoring data is carried out in a pumped-storage power station, this model combined with settlement activity is used to make the single point deformation analysis, and then the whole settlement activity profile is drawn by clustering analysis. Considering the cumulative settlement value of every point, the dam deformation trend is analyzed in an intuitive effect way. The analysis mode of combined single point with multipoints is realized. The results show that the key deformation information of the dam can be easily grasped by the application of the periodic average system model combined with the distribution diagram of settlement activity. And, above all, the ideas of this research provide an effective method for dam deformation analysis.
Final Report on Models, Periodic Progress, Report No D1.3, Globeman21, ESPRIT 26509
DEFF Research Database (Denmark)
Pedersen, Jens Dahl; Tølle, Martin; Vesterager, Johan
1999-01-01
This deliverable D1.3 is the third and final deliverable of WP1 - Global Manufacturing Concept of the European part of the Globeman21 project. The report essentially presents the final models on generic Extended Enterprise Management (EEM) and generic Product Life Cycle Management (PLCM), a colle......This deliverable D1.3 is the third and final deliverable of WP1 - Global Manufacturing Concept of the European part of the Globeman21 project. The report essentially presents the final models on generic Extended Enterprise Management (EEM) and generic Product Life Cycle Management (PLCM......), a collection of practical experiences, and requirements for enhanced methods and tools for modelling. First, the deliverable outlines the GM21 understanding regarding extended enterprises and virtual enterprises. This is done by extracting and synthesising the essence of key definitions and concepts...... enterprise context. Through the set of recommended activities for individual life cycle phases of respectively the network entity, the VE entity, and the product entity of the Extended Enterprise Framework, the methodology supports realisation of extended enterprises. The time sequenced planning...
Sasorova, Elena; Levin, Boris
2014-05-01
events. The statistical value Z was calculated. The confidence interval for a=1% (significance value) defined by the condition |Zcrit|=|Zcrit| then given sample may contain non-random components. The Z values for all magnitude ranges exceeded |Zcrit| in several times, thus a periodic transfer of the seismic activity between the Northern Hemisphere and the Southern Hemispheres is confirmed. The digital model (superposition of the random processes and the periodic process) was proposed. It was shown that statistical validity of the periodic component according to run test depends on: the frequency of the periodic function, and the duration of the observation period, and the probability of random component occurrence (P1) as function of time and the probability of the periodic component occurrence (P2) as function of time. The digital model enables to comprehend some particular features of the observation data.
An eLIMA model for the 67 s X-ray periodicity in CAL 83
Odendaal, A.; Meintjes, P. J.
2017-01-01
Supersoft X-ray sources (SSSs) are characterized by their low effective temperatures and high X-ray luminosities. The soft X-ray emission can be explained by hydrogen nuclear burning on the surface of a white dwarf (WD) accreting at an extremely high rate. A peculiar ˜67 s periodicity (P67) was previously discovered in the XMM-Newton light curves of the SSS CAL 83. P67 was detected in X-ray light curves spanning ˜9 years, but exhibits variability of several seconds on time-scales as short as a few hours, and its properties are remarkably similar to those of dwarf nova oscillations (DNOs). DNOs are short time-scale modulations (≲1 min) often observed in dwarf novae during outburst. DNOs are explained by the well established low-inertia magnetic accretor (LIMA) model. In this paper, we show that P67 and its associated period variability can be satisfactorily explained by an application of the LIMA model to the more `extreme' environment in a SSS (eLIMA), contrary to another recent study attempting to explain P67 and its associated variability in terms of non-radial g-mode oscillations in the extended envelope of the rapidly accreting white dwarf in CAL 83. In the eLIMA model, P67 originates in an equatorial belt in the WD envelope at the boundary with the inner accretion disc, with the belt weakly coupled to the WD core by a ˜105 G magnetic field. New optical light curves obtained with the Sutherland High-speed Optical Camera (SHOC) are also presented, exhibiting quasi-periodic modulations on time-scales of ˜1000 s, compatible with the eLIMA framework.
Directory of Open Access Journals (Sweden)
Camilo Noreña H
2011-05-01
Full Text Available Objective: to describe the research production of undergraduate students from the National Faculty of Public Health (Facultad Nacional de Salud Pública, FNSP, Universidad deAntioquia, during the period 2004-2008. Methods: descriptive study document review. The Study population was limited to graduation projects according to their different modalities (research projects, development project and monographs of the three undergraduate programs at the FNSP and research papers published in the Revista Facultad Nacional de SaludPública during the period 2004-2008. The analysis unit was restricted to graduation projects that could be located at the FNSP library and research papers including undergraduatestudents as authors. Descriptive statistics were used for the analysis of the data collected. Results: a total amount of 279 graduation projects were reviewed, from wich 119 (42.7% were research projects. In the undergraduate program of Management of Health Information Systems, research projects were the most frequent type of graduation project (79.1%. This proportion was smaller in the health administration programs both in its emphasis in health services (36.2% and in its emphasis on environment and sanitation (19.7%. A total amount of 126 research papers were reviewd finding 22 (17.5% with undergraduate students of the FNSP as coauthors. The proportion of research projects published in the Revista FNSP was 11.8%. Conclusions: during the period2004-2008, two out of five graduation projects in the FNSPwere research projects. During the period studied important differences according to the undergraduate programs were observed. The proportion of research projects published in the Revista FNSP is still very small.
Dynamic behavior of dissymmetric rotor bearings modelled with a periodic coefficient large system
Guilhen, P. M.; Berthier, P.; Ferraris, G.; Lalanne, M.
1987-01-01
The instability and unbalance response of dissymmetric rotor-bearing systems containing periodic coefficients when modeling produces matrices with a large number of degrees of freedom are discussed. It is important to solve the equations and then predict the dynamic behavior of the system. This can be done knowing the instability areas and the unbalance response in the stable areas. One deals here with a large number of equations and a reduction of the number of degrees of freedom of the system is achieved through a pseudo modal method. This method is shown to give satisfactory results.
The exhaustion problem in the periodic Anderson model: An X-boson approach
Energy Technology Data Exchange (ETDEWEB)
Franco, R. [Departamento de Fisica, Universidad Nacional de Colombia, Ciudadela Universidad Nacional, Bogota (Colombia)]. E-mail: rfrancop@unal.edu.co; Silva-Valencia, J. [Departamento de Fisica, Universidad Nacional de Colombia, Ciudadela Universidad Nacional, Bogota (Colombia); Figueira, M.S. [Instituto de Fisica da Universidade Federal Fluminense, Av. Litoranea s/n, 24210-340 Niteroi, Rio de Janeiro C.P.100.093 (Brazil)
2006-10-01
We study the thermodynamical properties of the periodic Anderson model (PAM), within the X-boson approach. The exhaustion problem is studied and we calculate the entropy and the specific heat for the heavy fermion Kondo regime (HF-K) of the PAM. We compute numerically the evolution of the Kondo lattice T{sub KL} and the Fermi liquid T{sup *} temperatures as function of the conduction electron occupation number n{sub c}. The results obtained are consistent with others reported in the literature for the Kondo lattice.
Topological Invariants of Edge States for Periodic Two-Dimensional Models
Energy Technology Data Exchange (ETDEWEB)
Avila, Julio Cesar; Schulz-Baldes, Hermann, E-mail: schuba@mi.uni-erlangen.de; Villegas-Blas, Carlos [Instituto de Matematicas, UNAM (Mexico)
2013-06-15
Transfer matrix methods and intersection theory are used to calculate the bands of edge states for a wide class of periodic two-dimensional tight-binding models including a sublattice and spin degree of freedom. This allows to define topological invariants by considering the associated Bott-Maslov indices which can be easily calculated numerically. For time-reversal symmetric systems in the symplectic universality class this leads to a Z{sub 2} -invariant for the edge states. It is shown that the edge state invariants are related to Chern numbers of the bulk systems and also to (spin) edge currents, in the spirit of the theory of topological insulators.
Inventory Model (Q, R) With Period of Grace, Quadratic Backorder Cost and Continuous Lead Time
Dr. Martin Osawaru Omorodion
2015-01-01
The paper considers the simple economic order model where the period of grace is operating, the lead time is continuous and the backorder cost is quadratic. The lead time follows a gamma distribution. The expected backorder cost per cycle is derived and averaged over all the states of the lead time L. Next we obtain the expected on hand inventory. The Lead time is taken as a Normal variate. The expected backorder costs are, derived after which the expected on hand inventory is derived. The...
She, M.; Jiang, L. P.
2014-12-01
In this paper, an oscillating dark energy model is presented in an isotropic but inhomogeneous plane symmetric space-time by considering a time periodic varying deceleration parameter. We find three different types of new solutions which describe different scenarios of oscillating universe. The first two solutions show an oscillating universe with singularities. For the third one, the universe is singularity-free during the whole evolution. Moreover, the Hubble parameter oscillates and keeps positive which explores an interesting possibility to unify the early inflation and late time acceleration of the universe.
Directory of Open Access Journals (Sweden)
G.S. Vorobjov
2015-06-01
Full Text Available General procedure for modeling the excitation conditions of Cherenkov and diffraction radiations in periodic metal-dielectric structures is described. It is based on the representation of the electron beam space-charge wave in the form of a dielectric waveguide surface-wave. On the experimental facility of millimeter-wave the basic modes of excitation conditions of spatial harmonics of the Cherenkov and diffraction radiations are simulated. The method is tested by comparing the numerical analysis and experimental results on the layout of the device of the orotron type - generator of diffraction radiation.
Topological invariants of edge states for periodic two-dimensional models
Avila, Julio Cesar; Villegas-Blas, Carlos
2012-01-01
Transfer matrix methods and intersection theory are used to calculate the bands of edge states for a wide class of periodic two-dimensional tight-binding models including a sublattice and spin degree of freedom. This allows to define topological invariants by considering the associated Bott-Maslov indices which can be easily calculated numerically. For time-reversal symmetric systems in the symplectic universality class this leads to a Z_2-invariant for the edge states. It is shown that the edge state invariants are related to Chern numbers of the bulk systems and also to (spin) edge currents, in the spirit of the theory of topological insulators.
Variational Monte Carlo study of magnetic states in the periodic Anderson model
Kubo, Katsunori
2015-03-01
We study the magnetic states of the periodic Anderson model with a finite Coulomb interaction between f electrons on a square lattice by applying variational Monte Carlo method. We consider Gutzwiller wavefunctions for the paramagnetic, antiferromagnetic, ferromagnetic, and charge density wave states. We find an antiferromagnetic phase around half-filling. There is a phase transition accompanying change in the Fermi-surface topology in this antiferromagnetic phase. We also study a case away from half-filling, and find a ferromagnetic state as the ground state there.
Optimal Harvesting in a Periodic Food Chain Model with Size Structures in Predators
Energy Technology Data Exchange (ETDEWEB)
Zhang, Feng-Qin, E-mail: zhafq@263.net [Yuncheng University, Department of Applied Mathematics (China); Liu, Rong [Lvliang University, Department of Mathematics (China); Chen, Yuming, E-mail: ychen@wlu.ca [Yuncheng University, Department of Applied Mathematics (China)
2017-04-15
In this paper, we investigate a periodic food chain model with harvesting, where the predators have size structures and are described by first-order partial differential equations. First, we establish the existence of a unique non-negative solution by using the Banach fixed point theorem. Then, we provide optimality conditions by means of normal cone and adjoint system. Finally, we derive the existence of an optimal strategy by means of Ekeland’s variational principle. Here the objective functional represents the net economic benefit yielded from harvesting.
Modeling DNA-Bending in the Nucleosome: Role of AA Periodicity
Prytkova, Tatiana; Zhu, Xiao; Widom, Jonathan; Schatz, George C.
2011-01-01
This paper uses atomistic molecular mechanics within the framework of the Jumna model to study the bending properties of DNA segments, with emphasis on understanding the role of the 10 bp periodicity associated with AA repeats that has been found to dominate in nucleosomal DNA. The calculations impose a bending potential on 18 bp segments that is consistent with nucleosome structures (i.e., radius of curvature of 4.1 nm), and then determine the energies of the minimum energy structures for di...
A Simple Economic Model of Cocaine Production
1994-01-01
the production dhain that are vulnerable to itr o as well as providing a clearer picture of the path that cocaine takes before reading retail markts in...In fact, given the volatility of cocaine product prices in PBC, it is probably not uncommon for segments of production to be unprofitable at times
Goal Model Integration for Tailoring Product Line Development Processes
Directory of Open Access Journals (Sweden)
Arfan Mansoor
2016-07-01
Full Text Available Many companies rely on the promised benefits of product lines, targeting systems between fully custom made software and mass products. Such customized mass products account for a large number of applications automatically derived from a product line. This results in the special importance of product lines for companies with a large part of their product portfolio based on their product line. The success of product line development efforts is highly dependent on tailoring the development process. This paper presents an integrative model of influence factors to tailor product line development processes according to different project needs, organizational goals, individual goals of the developers or constraints of the environment. This model integrates goal models, SPEM models and requirements to tailor development processes.
Information Sharing In Shipbuilding based on the Product State Model
DEFF Research Database (Denmark)
Larsen, Michael Holm
1999-01-01
The paper provides a review of product modelling technologies and the overall architecture for the Product State Model (PSM) environment as a basis for how dynamically updated product data can improve control of production activities. Especially, the paper focuses on the circumstances prevailing...... in a one-of-a-kind manufacturing environment like the shipbuilding industry, where product modelling technologies already have proved their worth in the design and engineering phases of shipbuilding and in the operation phase. However, the handling of product information on the shop floor is not yet...
Cai, L; Nyachoti, C M; Hancock, J D; Lee, J Y; Kim, Y H; Lee, D H; Kim, I H
2016-06-01
The objective of this study was to determine the effects of rare earth element-enriched yeast (RY) on egg production, coefficient of total tract apparent digestibility (CTTAD), egg quality, excreta gas emission and excreta microbiota of laying hens. A total of 216 ISA brown laying hens of 52 weeks of age were used in a 5-week feeding trial and data were collected every week. Birds were randomly allotted to three dietary treatments each with six replicates and 12 hens per replicate. Each cage (38 cm width × 50 cm length × 40 cm height) contained one hen. Treatments consisted of corn-soya bean meal-based diet supplemented with 0, 500 or 1000 mg/kg of RY. From weeks 55 to 56, inclusion of RY linearly increased (p production. The CTTAD of nitrogen was increased (linear, p units were increased linearly (p production and CTTAD of nitrogen and slightly improved egg quality in laying hens of the late period of peak egg production.
Directory of Open Access Journals (Sweden)
Angelina Maria de Oliveira Licório
2014-09-01
Full Text Available This article aims to characterize the scientific production on "knowledge management", published in Scielo database, from 1999 to 2012, through bibliometric analysis. The methodological procedures, in the first phase, uses predominantly quantitative, descriptive and documentary research, and in a second, a qualitative approach. Considering some limits, it has reached 63 publications, being 3 abstracts of thesis, 1 editorial and 59 articles defined as research sample. The criteria for the analysis are identification of periodic, the years of highest incidence, the number of authors per publication and their scientific production, authors' affiliation, philosophical conception and adopted research strategy. The results point to a methodological inconsistency in the drafting of the articles and a small number of published articles. A high incidence of only one publication per author is observed, showing that the production is more a result of specific work in graduate programs than the reflection and continued studies of the topic. Among other things, we have concluded that the researchers need to invest more in the field in order to expand it.
Piristine, Hande C; Choetso, Tenzin; Gobes, Sharon M H
2016-11-01
Sensory feedback is essential for acquiring and maintaining complex motor behaviors, including birdsong. In zebra finches, auditory feedback reaches the song control circuits primarily through the nucleus interfacialis nidopalii (Nif), which provides excitatory input to HVC (proper name)-a premotor region essential for the production of learned vocalizations. Despite being one of the major inputs to the song control pathway, the role of Nif in generating vocalizations is not well understood. To address this, we transiently inactivated Nif in late juvenile zebra finches. Upon Nif inactivation (in both hemispheres or on one side only), birds went from singing stereotyped zebra finch song to uttering highly variable and unstructured vocalizations resembling sub-song, an early juvenile song form driven by a basal ganglia circuit. Simultaneously inactivating Nif and LMAN (lateral magnocellular nucleus of the anterior nidopallium), the output nucleus of a basal ganglia circuit, inhibited song production altogether. These results suggest that Nif is required for generating the premotor drive for song. Permanent Nif lesions, in contrast, have only transient effects on vocal production, with song recovering within a day. The sensorimotor nucleus Nif thus produces a premotor drive to the motor pathway that is acutely required for generating learned vocalizations, but once permanently removed, the song system can compensate for its absence. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1213-1225, 2016.
Huang, Yun; Sun, Yahui; Liao, Qiang; Fu, Qian; Xia, Ao; Zhu, Xun
2016-09-01
To improve light penetrability and biomass production in batch cultivation, a cultivation mode that periodically pre-harvesting partial microalgae cells from suspension with culture medium recycling was proposed. By daily pre-harvesting 30% microalgae cells from the suspension, the average light intensity in the photobioreactor (PBR) was enhanced by 27.05-122.06%, resulting in a 46.48% increase in total biomass production than that cultivated in batch cultivation without pre-harvesting under an incident light intensity of 160μmolm(-2)s(-1). Compared with the semi-continuous cultivation with 30% microalgae suspension daily replaced with equivalent volume of fresh medium, nutrients and water input was reduced by 60% in the proposed cultivation mode but with slightly decrease (12.82%) in biomass production. No additional nutrient was replenished when culture medium recycling. Furthermore, higher pre-harvesting ratios (40%, 60%) and lower pre-harvesting frequencies (every 2, 2.5days) were not advantageous for the pre-harvesting cultivation mode. Copyright © 2016 Elsevier Ltd. All rights reserved.
Optimal control policies for continuous review production-inventory models
Germs, Remco; Foreest, Nicky D. van
2012-01-01
In this paper, we consider a stochastic version of a single-item production-inventory system in which the demand process is a mixture of a compound Poisson process and a constant demand rate. This model generalizes classical continuous-review single product inventory models with infinite planning horizon such as the EOQ model or production-inventory models with compound Poisson demand. We establish for the first time conditions on the inventory costs and the demand distribution such that the ...
Developing an Integrated Set of Production Planning and Control Models
Wang, Hui
2012-01-01
This paper proposes an integrated set of production planning and control models that can be applied in the Push system (Make-to-stock). The integrated model include forecasting, aggregate planning, materials requirements planning, inventory control, capacity planning and scheduling. This integrated model solves the planning issues via three levels, which include strategic level, tactical level and operational level. The model obtains the optimal production plan for each product type in each p...
Optimal control policies for continuous review production-inventory models
Germs, Remco; Foreest, Nicky D. van
2012-01-01
In this paper, we consider a stochastic version of a single-item production-inventory system in which the demand process is a mixture of a compound Poisson process and a constant demand rate. This model generalizes classical continuous-review single product inventory models with infinite planning horizon such as the EOQ model or production-inventory models with compound Poisson demand. We establish for the first time conditions on the inventory costs and the demand distribution such that the ...
Staphylococcus aureus bacteremia: comparison of two periods and a predictive model of mortality
Directory of Open Access Journals (Sweden)
Lucieni de Oliveira Conterno
2002-12-01
Full Text Available Staphylococcus aureus is an important pathogen causing bacteremia, primarily affecting hospitalized patients. We studied the epidemiology of S. aureus bacteremia, comparing two periods (early and mid 1990s and developed a predictive model of mortality. A nested case-control was done. All 251 patients over 14 years old with positive blood cultures for S. aureus were selected. MRSA (methicillin resistant S. aureus was isolated in 63% of the cases. When comparing the two periods MRSA community-acquired bacteremia increased from 4% to 16% (p=0.01. There was no significant difference in the mortality rate between the two periods (39% and 33%, p=0.40. Intravascular catheters provoked 24% of the cases of bacteremia and were associated with the lowest rate of mortality. In a logistic regression analysis, three variables were associated with death: septic shock, source of bacteraemia and resistance to methicillin. The probability of dying among patients with MRSA and those with methicillin sensitive S. aureus bacteraemia ranged from 10% to 90% and from 4% to 76%, respectively, depending on the source of the bacteraemia and the occurrence of septic shock. The MRSA found in Brazil may be a particularly virulent strain.
Information Technology Model for Product Lifecycle Engineering
Directory of Open Access Journals (Sweden)
Bhanumathi KS
2013-02-01
Full Text Available An aircraft is a complex, multi-disciplinary, system-engineered product that requires real-time global technical collaboration through its life-cycle. Engineering data and processes which form the backbone of the aircraft should be under strict Configuration Control (CC. It should be model-based and allow for 3D visualization and manipulation. This requires accurate, realtime collaboration and concurrent engineering-based business processes operating in an Integrated Digital Environment (IDE. The IDE uses lightweight, neutral Computer Aided Design (CAD Digital Mock-Up (DMU. The DMU deals with complex structural assemblies and systems of more than a hundred thousand parts created by engineers across the globe, each using diverse CAD, Computer Aided Engineering (CAE, Computer Aided Manufacturing (CAM, Computer Integrated Manufacturing (CIM, Enterprise Resource Planning (ERP, Supply Chain Management(SCM,Customer Relationship Management(CRM and Computer Aided Maintenance Management System (CAMMS systems. In this paper, a comprehensive approach to making such an environment a reality is presented.
Modeling dark fermentation for biohydrogen production: ADM1-based model vs. Gompertz model
Energy Technology Data Exchange (ETDEWEB)
Gadhamshetty, Venkataramana [Air Force Research Laboratory, Tyndall AFB, 139 Barnes Drive, Panama City, FL 32403 (United States); Arudchelvam, Yalini; Nirmalakhandan, Nagamany [Civil Engineering Department, New Mexico State University, Las Cruces, NM 88003 (United States); Johnson, David C. [Institute for Energy and Environment, New Mexico State University, Las Cruces, NM 88003 (United States)
2010-01-15
Biohydrogen production by dark fermentation in batch reactors was modeled using the Gompertz equation and a model based on Anaerobic Digestion Model (ADM1). The ADM1 framework, which has been well accepted for modeling methane production by anaerobic digestion, was modified in this study for modeling hydrogen production. Experimental hydrogen production data from eight reactor configurations varying in pressure conditions, temperature, type and concentration of substrate, inocula source, and stirring conditions were used to evaluate the predictive abilities of the two modeling approaches. Although the quality of fit between the measured and fitted hydrogen evolution by the Gompertz equation was high in all the eight reactor configurations with r{sup 2} {proportional_to}0.98, each configuration required a different set of model parameters, negating its utility as a general approach to predict hydrogen evolution. On the other hand, the ADM1-based model (ADM1BM) with predefined parameters was able to predict COD, cumulative hydrogen production, as well as volatile fatty acids production, albeit at a slightly lower quality of fit. Agreement between the experimental temporal hydrogen evolution data and the ADM1BM predictions was statistically significant with r{sup 2} > 0.91 and p-value <1E-04. Sensitivity analysis of the validated model revealed that hydrogen production was sensitive to only six parameters in the ADM1BM. (author)
Mansfeld, R; Sauter-Louis, C; Martin, R
2012-01-01
In terms of milk production, the dry period (DP) is a non-productive time. In addition, the risk of mastitis increases when cows with daily milk yield >12.5kg are dried off, which is often the case when the DP is set to 55-60 days. References on the positive effects of a shortened DP on the metabolic health at the start of lactation and the subsequent reproductive performance were the motive of this review. Completely foregoing or shortening the DP produces a decrease in milk yield during the following lactation. This decrease is particularly pronounced for cows at the beginning of the second lactation. It is thought that this may be due in part to different involution and proliferation processes of the mammary glands in primiparous and multiparous animals. The majority of the scientific papers suggest that shortening the DP has a positive rather than a negative effect on udder health. The quality of the colostrum is also unaffected; but if there is no drying off, the colostrum will be diluted. When considered overall, the literature, with support from metabolic profile studies, appears to favour a reduced impact on energy metabolism in early lactation in circumstances when the DP is shortened or waived. Clear positive effects on parameters relevant to energy metabolism however only apply to multiparous animals, and other factors, such as milking frequency before and after calving, exert an influence. Positive effects of shortening the DP on the reproductive performance were shown in several studies. Time from calving to first ovulation as well as indicators for assessing the success of artificial insemination and reproductive performance showed better results in animals with no or shortened drying off periods. Again, this only applied to multiparous animals. Overall, there is no single clear answer to the question of an optimal length of the DP, but conversely it is abundantly clear that a dry period of 55-60 days is not necessary in all cases and does not make
Solid-state three-step model for high-harmonic generation from periodic crystals
Ikemachi, Takuya; Sato, Takeshi; Yumoto, Junji; Kuwata-Gonokami, Makoto; Ishikawa, Kenichi L
2016-01-01
We study high-harmonic generation (HHG) from solids driven by intense laser pulses using the time-dependent Schrodinger equation for a one-dimensional model periodic crystal. Based on the simulation results, we propose a simple model that can quantitatively explain many aspects of solid- state HHG, some of which have been experimentally observed. Incorporating interband tunneling, intraband acceleration, and recombination with the valence-band hole, our model can be viewed as a solid-state counterpart of the familiar three-step model highly successful for gas-phase HHG and provides a unified basis to understand HHG from gaseous media and solid-state materials. The solid-state three-step model describes how, by repeating intraband acceleration and interband tunneling, electrons climb up across multiple conduction bands. The key parameter in predicting the HHG spectrum structure from the band-climbing process is the peak-to-valley (or valley-to-peak) full amplitude of the pulse vector potential $A(t)$. When the...
Institute of Scientific and Technical Information of China (English)
无
2012-01-01
The positive periodic solutions to a three-species delayed Lotka-Volterra model with dispersion and harvesting terms are studied in this paper. By the coincidence degree theory, the sufficient conditions for existence of eight positive periodic solutions to the model are obtained.
Analysis of a Periodic Single Species Population Model Involving Constant Impulsive Perturbation
Directory of Open Access Journals (Sweden)
Ronghua Tan
2014-01-01
Full Text Available This is a continuation of the work of Tan et al. (2012. In this paper a periodic single species model controlled by constant impulsive perturbation is investigated. The constant impulse is realized at fixed moments of time. With the help of the comparison theorem of impulsive differential equations and Lyapunov functions, sufficient conditions for the permanence and global attractivity are established, respectively. Also, by comparing the above results with corresponding known results of Tan et al. (2012 (i.e., the above model with linear impulsive perturbations, we find that the two different types of impulsive perturbations have influence on the above dynamics. Numerical simulations are presented to substantiate our analytical results.
Multiple periodic solutions for a discrete time model of plankton allelopathy
Zhang Jianbao; Fang Hui
2006-01-01
We study a discrete time model of the growth of two species of plankton with competitive and allelopathic effects on each other N1(k+1) = N1(k)exp{r1(k)-a11(k)N1(k)-a12(k)N2(k)-b1(k)N1(k)N2(k)}, N2(k+1) = N2(k)exp{r2(k)-a21(k)N2(k)-b2(k)N1(k)N1(k)N2(k)}. A set of sufficient conditions is obtained for the existence of multiple positive periodic solutions for this model. The approach is based on Mawhin's continuation theorem of coincidence degree theory as well as some a priori estimates. Some...
Periodic and chaotic oscillations in a tumor and immune system interaction model with three delays
Energy Technology Data Exchange (ETDEWEB)
Bi, Ping [Department of Mathematics, Shanghai Key Laboratory of PMMP, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Center for Partial Differential Equations, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China); Ruan, Shigui, E-mail: ruan@math.miami.edu [Department of Mathematics, University of Miami, Coral Gables, Florida 33124-4250 (United States); Zhang, Xinan [School of Mathematics and Statistics, Central China Normal University, Wuhan 430079 (China)
2014-06-15
In this paper, a tumor and immune system interaction model consisted of two differential equations with three time delays is considered in which the delays describe the proliferation of tumor cells, the process of effector cells growth stimulated by tumor cells, and the differentiation of immune effector cells, respectively. Conditions for the asymptotic stability of equilibria and existence of Hopf bifurcations are obtained by analyzing the roots of a second degree exponential polynomial characteristic equation with delay dependent coefficients. It is shown that the positive equilibrium is asymptotically stable if all three delays are less than their corresponding critical values and Hopf bifurcations occur if any one of these delays passes through its critical value. Numerical simulations are carried out to illustrate the rich dynamical behavior of the model with different delay values including the existence of regular and irregular long periodic oscillations.
Directory of Open Access Journals (Sweden)
Eleftherios Giovanis
2014-12-01
Full Text Available The current study examines the turn of the month effect on stock returns in 20 countries. This will allow us to explore whether the seasonal patterns usually found in global data; America, Australia, Europe and Asia. Ordinary Least Squares (OLS is problematic as it leads to unreliable estimations; because of the autocorrelation and Autoregressive Conditional Heteroskedasticity (ARCH effects existence. For this reason Generalized GARCH models are estimated. Two approaches are followed. The first is the symmetric Generalized ARCH (1,1 model. However, previous studies found that volatility tends to increase more when the stock market index decreases than when the stock market index increases by the same amount. In addition there is higher seasonality in volatility rather on average returns. For this reason the Periodic-GARCH (1,1 is estimated. The findings support the persistence of the specific calendar effect in 19 out of 20 countries examined.
A Traffic Information Estimation Model Using Periodic Location Update Events from Cellular Network
Lin, Bon-Yeh; Chen, Chi-Hua; Lo, Chi-Chun
In recent years considerable concerns have arisen over building Intelligent Transportation System (ITS) which focuses on efficiently managing the road network. One of the important purposes of ITS is to improve the usability of transportation resources so as extend the durability of vehicle, reduce the fuel consumption and transportation times. Before this goal can be achieved, it is vital to obtain correct and real-time traffic information, so that traffic information services can be provided in a timely and effective manner. Using Mobile Stations (MS) as probe to tracking the vehicle movement is a low cost and immediately solution to obtain the real-time traffic information. In this paper, we propose a model to analyze the relation between the amount of Periodic Location Update (PLU) events and traffic density. Finally, the numerical analysis shows that this model is feasible to estimate the traffic density.
Multiple periodic solutions for a discrete time model of plankton allelopathy
Zhang Jianbao; Fang Hui
2006-01-01
We study a discrete time model of the growth of two species of plankton with competitive and allelopathic effects on each other N1(k+1) = N1(k)exp{r1(k)-a11(k)N1(k)-a12(k)N2(k)-b1(k)N1(k)N2(k)}, N2(k+1) = N2(k)exp{r2(k)-a21(k)N2(k)-b2(k)N1(k)N1(k)N2(k)}. A set of sufficient conditions is obtained for the existence of multiple positive periodic solutions for this model. The approach is based on Mawhin's continuation theorem of coincidence degree theory as well as some a priori estimates. Some...
Threshold Dynamics of a Huanglongbing Model with Logistic Growth in Periodic Environments
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Jianping Wang
2014-01-01
Full Text Available We analyze the impact of seasonal activity of psyllid on the dynamics of Huanglongbing (HLB infection. A new model about HLB transmission with Logistic growth in psyllid insect vectors and periodic coefficients has been investigated. It is shown that the global dynamics are determined by the basic reproduction number R0 which is defined through the spectral radius of a linear integral operator. If R0 1, then the disease persists. Numerical values of parameters of the model are evaluated taken from the literatures. Furthermore, numerical simulations support our analytical conclusions and the sensitive analysis on the basic reproduction number to the changes of average and amplitude values of the recruitment function of citrus are shown. Finally, some useful comments on controlling the transmission of HLB are given.
Final Report on Models, Periodic Progress, Report No D1.3, Globeman21, ESPRIT 26509
DEFF Research Database (Denmark)
Pedersen, Jens Dahl; Tølle, Martin; Vesterager, Johan
1999-01-01
This deliverable D1.3 is the third and final deliverable of WP1 - Global Manufacturing Concept of the European part of the Globeman21 project. The report essentially presents the final models on generic Extended Enterprise Management (EEM) and generic Product Life Cycle Management (PLCM...... accomplished during the GM21EU project. Especially the Extended Enterprise Framework should be accentuated as a key concept of WP1. Building on ISO/DIS 15704 GERAM, the framework constitutes a generic reference model for extended enterprises and hereunder for EEM and PLCM issues. The Extended Enterprise...... classification schema for work preparation in extended enterprises. The classification schema is applied as support for a mapping of the EEM and PLCM pilot projects onto the Extended Enterprise Framework. By mapping the industrial pilot work onto a common reference model experiences have been collected from GM21...
Development of Extended Period Pressure-Dependent Demand Water Distribution Models
Energy Technology Data Exchange (ETDEWEB)
Judi, David R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mcpherson, Timothy N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-03-20
Los Alamos National Laboratory (LANL) has used modeling and simulation of water distribution systems for N-1 contingency analyses to assess criticality of water system assets. Critical components considered in these analyses include pumps, tanks, and supply sources, in addition to critical pipes or aqueducts. A contingency represents the complete removal of the asset from system operation. For each contingency, an extended period simulation (EPS) is run using EPANET. An EPS simulates water system behavior over a time period, typically at least 24 hours. It assesses the ability of a system to respond and recover from asset disruption through distributed storage in tanks throughout the system. Contingencies of concern are identified as those in which some portion of the water system has unmet delivery requirements. A delivery requirement is defined as an aggregation of water demands within a service area, similar to an electric power demand. The metric used to identify areas of unmet delivery requirement in these studies is a pressure threshold of 15 pounds per square inch (psi). This pressure threshold is used because it is below the required pressure for fire protection. Any location in the model with pressure that drops below this threshold at any time during an EPS is considered to have unmet service requirements and is used to determine cascading consequences. The outage area for a contingency is the aggregation of all service areas with a pressure below the threshold at any time during the EPS.
Property Modelling for Applications in Chemical Product and Process Design
DEFF Research Database (Denmark)
Gani, Rafiqul
Physical-chemical properties of pure chemicals and their mixtures play an important role in the design of chemicals based products and the processes that manufacture them. Although, the use of experimental data in design and analysis of chemicals based products and their processes is desirable...... such as database, property model library, model parameter regression, and, property-model based product-process design will be presented. The database contains pure component and mixture data for a wide range of organic chemicals. The property models are based on the combined group contribution and atom...... modeling tools in design and analysis of chemical product-process design, including biochemical processes will be highlighted....
Directory of Open Access Journals (Sweden)
C. Contoux
2012-06-01
Full Text Available This paper describes the experimental design and model results of the climate simulations of the mid-Pliocene Warm Period (mPWP, ca. 3.3–3 Ma using the Institut Pierre Simon Laplace model (IPSLCM5A, in the framework of the Pliocene Model Intercomparison Project (PlioMIP. We use the IPSL atmosphere ocean general circulation model (AOGCM, and its atmospheric component alone (AGCM, to simulate the climate of the mPWP. Boundary conditions such as sea surface temperatures (SSTs, topography, ice-sheet extent and vegetation are derived from the ones imposed by the Pliocene Model Intercomparison Project (PlioMIP, described in Haywood et al. (2010, 2011. We first describe the IPSL model main features, and then give a full description of the boundary conditions used for atmospheric model and coupled model experiments. The climatic outputs of the mPWP simulations are detailed and compared to the corresponding control simulations. The simulated warming relative to the control simulation is 1.94 °C in the atmospheric and 2.07 °C in the coupled model experiments. In both experiments, warming is larger at high latitudes. Mechanisms governing the simulated precipitation patterns are different in the coupled model than in the atmospheric model alone, because of the reduced gradients in imposed SSTs, which impacts the Hadley and Walker circulations. In addition, a sensitivity test to the change of land-sea mask in the atmospheric model, representing a sea-level change from present-day to 25 m higher during the mid-Pliocene, is described. We find that surface temperature differences can be large (several degrees Celsius but are restricted to the areas that were changed from ocean to land or vice versa. In terms of precipitation, impact on polar regions is minor although the change in land-sea mask is significant in these areas.
A Model to Improve the Quality Products
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Hasan GOKKAYA
2010-08-01
Full Text Available The topic of this paper is to present a solution who can improve product qualityfollowing the idea: “Unlike people who have verbal skills, machines use "sign language"to communicate what hurts or what has invaded their system’. Recognizing the "signs"or symptoms that the machine conveys is a required skill for those who work withmachines and are responsible for their care and feeding. The acoustic behavior of technical products is predominantly defined in the design stage, although the acoustic characteristics of machine structures can be analyze and give a solution for the actual products and create a new generation of products. The paper describes the steps intechnological process for a product and the solution who will reduce the costs with the non-quality of product and improve the management quality.
Modelling Aspergillus flavus growth and aflatoxins production in pistachio nuts.
Marín, Sonia; Ramos, Antonio J; Sanchis, V
2012-12-01
Aflatoxins (AFs) are the main contaminants in pistachio nuts. AFs production in pistachio has been attributed to Aspergillus flavus. The aim of this study was to apply existing models to predict growth and AFs production by an A. flavus isolated from pistachios as a function of moisture content and storage temperature of pistachios in order to test their usefulness and complementarities. A full factorial design was used: the moisture content levels assayed were 10, 15, 20, 25 and 30% and incubation temperatures were 10, 15, 20, 25, 30, 37 and 42 °C. Both kinetic and probability models were built to predict growth of the strain under the assayed conditions. Among the assayed models, cardinal ones gave a good quality fit for radial growth rate data. Moreover, the progressive approach, which was developed based on a reduced number of experimental points led to an improved prediction in the validation step. This is quite significant as may allow for improved experimental designs, less costly than full factorial ones. Probability model proved to be concordant in 91% of the calibration set observations. Even though the validation set included conditions around the growth/no-growth interface, there was a 100% agreement in the predictions from the data set (n = 16, cut off = 0.5) after 60 days. Similarly, the probability for AF presence was rightly predicted in 89% of the cases. According to our results EC maximum aflatoxin levels would be surpassed in a period as short as 1 month if pistachio nuts reach 20 °C, unless %mc is ≤10%.
Mattila, P; Valaja, J; Rossow, L; Venäläinen, E; Tupasela, T
2004-03-01
Vitamin D insufficiency during winter is a common problem for humans in Europe. One way to ease this problem is through the production of vitamin D-fortified eggs. To evaluate such a production process, the effects of vitamin D supplementation during an entire production period were assessed. Transfer of vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol) from the diet to egg yolks was measured using 2 different levels of both vitamins (6,000 and 15,000 IU/kg feed) relative to a control treatment (2,500 IU vitamin D3/kg feed). During the experiment, production parameters, egg quality (egg weight, Haugh unit, specific gravity, eggshell fracture force, and Ca content of eggshell), and the condition of hens were monitored. At the end of the experiment histopathological tests were performed. Supplementing diets with vitamin D3 increased egg yolk vitamin D content more effectively than did supplementation with vitamin D2. For groups of hens receiving 6,000 or 15,000 IU of vitamin D3/kg feed, egg yolk vitamin D3 content ranged from 9.1 to 13.6 and from 25.3 to 33.7 microg/100 g, respectively. Corresponding values for birds fed vitamin D2 were 4.7 to 7.0 and 13.3 to 21.0 microg/100 g. Both supplements enhanced vitamin D3 content of egg yolks relative to the control diet (2.5 to 5.0 microg/100 g of egg yolk). Vitamin D supplements had no effects on production parameters compared with the control diet. However, especially vitamin D3 improved bone strength (P < 0.05). Autopsy at the end of the experiment indicated no detrimental accumulation of calcium in the kidneys, liver, heart, muscles, or lungs.
Aarif, Ovais; Aggarwal, Anjali
2016-03-01
This study aimed to evaluate the impact of evaporative cooling during late gestation on physiological responses, blood gas and acid base balance and subsequent milk production of Murrah buffaloes. To investigate this study sixteen healthy pregnant dry Murrah buffaloes (second to fourth parity) at sixty days prepartum were selected in the months of May to June and divided into two groups of eight animals each. One group of buffaloes (Cooled/CL) was managed under fan and mist cooling system during dry period. Group second buffaloes (Noncooled/NCL) remained as control without provision of cooling during dry period. The physiological responses viz. Rectal temperature (RT), Respiratory rate (RR) and Pulse rate were significantly ( P < 0.05) lower in group 2, with the provision of cooling. Skin surface temperature at thorax was significantly lower in cooled group relative to noncooled group. Blood pH and pO2 were significantly ( P < 0.05) higher in heat stressed group as compared to the cooled group. pCO2, TCO2, HCO3, SBC, base excess in extracellular fluid (BEecf), base excess in blood (BEb), PCV and Hb were significantly ( P < 0.05) higher in cooled group as compared to noncooled group. DMI was significantly ( P < 0.05) higher in cooled relative to noncooled animals. Milk yield, FCM, fat yield, lactose yield and total solid yield was significantly higher ( P < 0.05) in cooled group of Murrah buffaloes.
Aarif, Ovais; Aggarwal, Anjali
2016-03-01
This study aimed to evaluate the impact of evaporative cooling during late gestation on physiological responses, blood gas and acid base balance and subsequent milk production of Murrah buffaloes. To investigate this study sixteen healthy pregnant dry Murrah buffaloes (second to fourth parity) at sixty days prepartum were selected in the months of May to June and divided into two groups of eight animals each. One group of buffaloes (Cooled/CL) was managed under fan and mist cooling system during dry period. Group second buffaloes (Noncooled/NCL) remained as control without provision of cooling during dry period. The physiological responses viz. Rectal temperature (RT), Respiratory rate (RR) and Pulse rate were significantly (P base excess in extracellular fluid (BEecf), base excess in blood (BEb), PCV and Hb were significantly (P < 0.05) higher in cooled group as compared to noncooled group. DMI was significantly (P < 0.05) higher in cooled relative to noncooled animals. Milk yield, FCM, fat yield, lactose yield and total solid yield was significantly higher (P < 0.05) in cooled group of Murrah buffaloes.
Török, Gabriel; Urbanec, Martin; Šrámková, Eva; Adámek, Karel; Urbancová, Gabriela; Pecháček, Tomáš; Bakala, Pavel; Stuchlík, Zdeněk; Horák, Jiří; Juryšek, Jakub
2016-01-01
Twin-peak quasi-periodic oscillations (QPOs) are observed in the X-ray power-density spectra of several accreting low-mass neutron star (NS) binaries. In our previous work we have considered several QPO models. We have identified and explored mass-angular-momentum relations implied by individual QPO models for the atoll source 4U 1636-53. In this paper we extend our study and confront QPO models with various NS equations of state (EoS). We start with simplified calculations assuming Kerr background geometry and then present results of detailed calculations considering the influence of NS quadrupole moment (related to rotationally induced NS oblateness) assuming Hartle-Thorne spacetimes. We show that the application of concrete EoS together with a particular QPO model yields a specific mass-angular-momentum relation. However, we demonstrate that the degeneracy in mass and angular momentum can be removed when the NS spin frequency inferred from the X-ray burst observations is considered. We inspect a large set ...