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on Computational Economics |
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Issue of 2018‒09‒17
eleven papers chosen by |
| By: | Qie He (University of Minnesota); Stefan Irnich (Johannes Gutenberg-University); Yongjia Song (Virginia Commonwealth University) |
| Abstract: | Two critical yet frequently conflicting objectives for logistics and transportation service companies are improving customer satisfaction and reducing transportation cost. In particular, given a network of customer requests with preferred service times, it is very challenging to find vehicle routes and service schedules simultaneously that respect all operating constraints and minimize the total transportation and customers’ inconvenience costs. In this paper, we introduce the Vehicle Routing Problem with Time Windows and Convex Node Costs (VRPTW-CNC), in which we model each customer’s inconvenience cost as a convex function of the service start time at that customer. The VRPTW-CNC combines and extends both the standard vehicle routing problem with time windows and some previous results on the optimal service scheduling problem over a fixed route. We propose a branch-cut-and-price algorithm to solve the VRPTW-CNC with general convex inconvenience cost functions. To solve the pricing problem, our labeling algorithm only generates labels that possibly lead to optimal schedule times over a route, which significantly improves the effectiveness of pricing. Extensive computational results demonstrate the effectiveness of our approach. |
| Keywords: | Vehicle routing problem, branch-cut-and-price, labeling algorithm, convex node costs, integrated routing and scheduling |
| Date: | 2018–03–07 |
| URL: | http://d.repec.org/n?u=RePEc:jgu:wpaper:1804&r=cmp |
| By: | Leen, Frederik; Van den Broeke, Alice; Aluwé, Marijke; Ludwig, Lauwers; Sam, Millet; Jef, Van Meensel |
| Abstract: | A simulation model was developed to model the optimization problem of finishing pig delivery weights. The model was developed following a participatory problem analysis of the decision problem, to align the model as much as possible with the needs and expectations of the stakeholders. It’s functioning was tested by simulating different management strategies (i.e. finishing different sex combinations), in which differences in animal performance provoke different optima at the level of the animal and of a pig place per unit of time. The model’s results align with the findings of past studies modelling the delivery weight decision problem. |
| Keywords: | Farm Management, Productivity Analysis |
| Date: | 2017–08–28 |
| URL: | http://d.repec.org/n?u=RePEc:ags:eaae17:261272&r=cmp |
| By: | Boulanger, Pierre; Dillen, Koen; Dudu, Hasan; Ferrari, Emanuele; Himics, Mihaly; M'Barek, Robert; Philippidis, George |
| Abstract: | This paper presents potential effects of twelve free trade agreements (FTAs) under the current EU FTA agenda. With the help of two economic simulation models (the global CGE MAGNET and PE AGLINK), it sheds some light on relatively balanced cumulated impacts in terms of trade, production and price for the EU agricultural sector as a whole while quantifying also the market development for specific agricultural sectors. It compares a conservative and an ambitious FTA scenario with a business as usual (reference) scenario. |
| Keywords: | Agribusiness, Agricultural and Food Policy, Marketing |
| Date: | 2017–08–28 |
| URL: | http://d.repec.org/n?u=RePEc:ags:eaae17:261115&r=cmp |
| By: | John Leventides (Department of Economics, University of Athens, Greece); Kalliopi Loukaki (Department of Economics, University of Athens, Greece); Vassilios Papavassiliou (UCD Michael Smurfit Graduate Business School, University College Dublin, Ireland; Rimini Centre for Economic Analysis) |
| Abstract: | The purpose of this study is to assess the resilience of financial systems to exogenous shocks using techniques drawn from the theory of complex networks. We investigate by means of Monte Carlo simulations the fragility of several network topologies using a simple default model of contagion applied on interbank networks of varying sizes. We trigger a series of banking crises by exogenously failing each bank in the system and observe the propagation mechanisms that take effect within the system under different scenarios. Finally, we add to the existing literature by analyzing the interplay of several crucial drivers of interbank contagion, such as network topology, leverage, interconnectedness, heterogeneity and homogeneity across bank sizes and interbank exposures. |
| Keywords: | Interbank contagion, random networks, financial stability, interconnectedness, systemic risk |
| Date: | 2018–09 |
| URL: | http://d.repec.org/n?u=RePEc:rim:rimwps:18-34&r=cmp |
| By: | Viccaro, Mauro; Rocchi, Benedetto; Cozzi, Mario; Egging, Rudolf G.; Perez-Valdes, Gerardo A.; Romano, Severino |
| Abstract: | The development of bioenergy, as a new business model integrated with environment and territory, may be a valuable opportunity for farmers with positive effects both in socio-economic and environmental terms. However, largescale biomass plantations might increase pressure on the productive land and might cause a substantial increase of food prices. The main goal of the current study is to support the policy decision making in the renewable energy sector by quantitatively assessing impacts of alternative policy instruments at the sub-state regional level. The scenario analysis is performed using a multi-regional multi-sector Computable General Equilibrium (CGE) model applied to Basilicata region, Southern Italy, with, given the importance of agriculture in the area, a great deal attention on agricultural production level, food prices and land competition. Results shows that promoting bioenergy sector do not generate negative impact on food price, land use and welfare, supporting the continuation of policies to incentive the bioenergy sector, combining tax policies with other policy tools (e.g. agricultural or climate policies) in order to make the sector more competitive. |
| Keywords: | Agricultural and Food Policy |
| Date: | 2017–08–28 |
| URL: | http://d.repec.org/n?u=RePEc:ags:eaae17:261158&r=cmp |
| By: | Zawalińska, Katarzyna; Milczarek-Andrzejewska, Dominika |
| Abstract: | Urban sprawl is one of the most important reasons behind conflicts over farmland use. In that context, agricultural policy can be perceived as a guardian protecting farmland for agricultural purposes. The paper aims at investigating the role of the Common Agricultural Policy (CAP) in shaping farmland market in Poland. With use of regional Computable General Equilibrium (CGE) model we found out that CAP has led to farmland price distortions in most Polish regions but at the same time it has allowed to maintain land in agricultural use particularly in regions which heavily depend on agriculture and have fragmented farm structure. |
| Keywords: | Land Economics/Use |
| Date: | 2017–08–29 |
| URL: | http://d.repec.org/n?u=RePEc:ags:eaae17:260883&r=cmp |
| By: | Lu, Richard (?); Chatman, Jennifer A. (?); Goldberg, Amir (Stanford University); Srivastava, Sameer B. (?) |
| Abstract: | From the schoolyard to the boardroom, the pressures of cultural assimilation pervade all walks of social life. Why are some people more successful than others at cultural adjustment? Research on organizational culture has mostly focused on value congruence as the core dimension of cultural fit. We develop a complementary conceptualization of cognitive fit--perceptual accuracy, or the degree to which a person can decipher the group's cultural code. We demonstrate that the ability to read the cultural code, rather than identification with the code, matters for contemporaneous behavioral conformity. We further show that a person*s behavior and perceptual accuracy are both influenced by observations of others* behavior, whereas value congruence is less susceptible to peer influence. Drawing on email and survey data from a mid-sized technology firm, we use the tools of computational linguistics and machine learning to develop longitudinal measures of cognitive and behavioral cultural fit. We also take advantage of a reorganization that produced quasi-exogenous shifts in employees' interlocutors to identify the causal impact of peer influence. We discuss implications of these findings for research on cultural assimilation, the interplay of structure and culture, and the pairing of surveys with digital trace data. |
| Date: | 2018–05 |
| URL: | http://d.repec.org/n?u=RePEc:ecl:stabus:3603&r=cmp |
| By: | Smeets Kristkova, Zuzana; Smeets, Edward; Van Meijl, Hans |
| Abstract: | The objective of this study is to evaluate the possibilities and limitations of avoiding the undesirable effects of energy crops on land use and food security by increasing agricultural productivity through investments in R&D. An extended version of the MAGNET CGE model is used to model the R&D investments in agriculture to compensate the effects of 15 EJ to 100 EJ biomass supply from woody and grassy energy crop plantations. We conclude that investments in agriculture R&D are a potentially effective and low-cost strategy, but early planning and timing of bioenergy policies with investments in R&D in agriculture is essential. |
| Keywords: | Agricultural and Food Policy, Food Security and Poverty |
| Date: | 2017–08–29 |
| URL: | http://d.repec.org/n?u=RePEc:ags:eaae17:260822&r=cmp |
| By: | Zhipeng Liang; Kangkang Jiang; Hao Chen; Junhao Zhu; Yanran Li |
| Abstract: | In this paper, we implement two state-of-art continuous reinforcement learning algorithms, Deep Deterministic Policy Gradient (DDPG) and Proximal Policy Optimization (PPO) in portfolio management. Both of them are widely-used in game playing and robot control. What's more, PPO has appealing theoretical propeties which is hopefully potential in portfolio management. We present the performances of them under different settings, including different learning rate, objective function, markets, feature combinations, in order to provide insights for parameter tuning, features selection and data preparation. |
| Date: | 2018–08 |
| URL: | http://d.repec.org/n?u=RePEc:arx:papers:1808.09940&r=cmp |
| By: | Mansouri, R. |
| Abstract: | Abstract The Pressure Irrigation Networks is one of the major requirements in urban and regional economic development. For any agency dealing with the design of the water distribution network, an economic design will be an objective. In this research, Developed Central Force Optimization (DCFO) was used to optimize Ismail Abad water Distribution network. This network that is pressurized network and includes 19 pipes and nodes 18. Optimization of the network has been evaluated by developing an optimization model based on DCFO algorithm in MATLAB and the dynamic connection with EPANET software for network hydraulic calculation. Conclusions show DCFO runtime is less than mixed integer linear programming (MILP) method that provides absolute optimum. While optimization of DCFO (737,924 $) is 1.61% more than the absolute optimum that determined by the MILP method. The Frep parameter started at a value of 0.5 and was incremented by 0.005 whenever the absolute value of the difference between 5th array element and the average value of elements 3, 4, and 5 differed by less than 0.0005 (fitness tolerance). This method has been used to place 42 probes (Np = 42) in decision space and their initial acceleration vectors have been set to zero. |
| Keywords: | Agricultural and Food Policy, Crop Production/Industries |
| Date: | 2018–07 |
| URL: | http://d.repec.org/n?u=RePEc:ags:iaae18:275982&r=cmp |
| By: | Martin Burda; Remi Daviet |
| Abstract: | Practical use of nonparametric Bayesian methods requires the availability of efficient algorithms for implementation for posterior inference. The inherently serial nature of Markov Chain Monte Carlo (MCMC) imposes limitations on its efficiency and scalability. In recent years there has been a surge of research activity devoted to developing alternative implementation methods that target parallel computing environments. Sequential Monte Carlo (SMC), also known as a particle filter, has been gaining popularity due to its desirable properties. SMC uses a genetic mutation-selection sampling approach with a set of particles representing the posterior distribution of a stochastic process. We propose to enhance the performance of SMC by utilizing Hamiltonian transition dynamics in the particle transition phase, in place of random walk used in the previous literature. We call the resulting procedure Hamiltonian Sequential Monte Carlo (HSMC). Hamiltonian transition dynamics has been shown to yield superior mixing and convergence properties relative to random walk transition dynamics in the context of MCMC procedures. The rationale behind HSMC is to translate such gains to the SMC environment. We apply both SMC and HSMC to a panel discrete choice model with a nonparametric distribution of unobserved individual heterogeneity. We contrast both methods in terms of convergence properties and show the favorable performance of HSMC. |
| Keywords: | Particle filtering, Bayesian nonparametrics, mixed panel logit, discrete choice |
| JEL: | C11 C14 C15 C23 C25 |
| Date: | 2018–09–12 |
| URL: | http://d.repec.org/n?u=RePEc:tor:tecipa:tecipa-618&r=cmp |