How effective are heuristic solutions for electricity planning in developing countries

Heuristic algorithms have been widely used to provide computationally feasible means of exploring the cost effective balance between grid versus off grid sources for universal electrification in developing countries. By definition in such algorithms however, global optimality is not guaranteed. We present a computationally intensive but globally optimal mixed integer non-linear programming (MINLP) model for electricity planning and use it in a Monte Carlo simulation procedure to test the relative performance of a widely used heuristic algorithm due to [28]. We show that the overall difference in cost is typically small suggesting that the heuristic algorithm is generally cost effective in many situations. However we find that the relative performance of the heuristic algorithm deteriorates with increasing degree of spatial dispersion of unelectrified settlements, as well as increasing spatial remoteness of the settlements from the grid network, suggesting that the effectiveness of the heuristic algorithm is context specific. Further, we find that allocation of off grid sources in the heuristic algorithm solution is often significantly greater than in the MINLP model suggesting that heuristic methods can overstate the role of off-grid solutions in certain situations.     

A quintessential immigrant niche? The non-case of immigrants in the Dutch construction industry

Students of immigrant entrepreneurship show a distinct preference for ethnic concentrations. They focus on small entrepreneurship in sectors with large concentrations of immigrant businesses or on ethnic commercial precincts. This preference stems from practical and theoretical considerations. It seems that the study of such concentrations, or niches, is essential to the theoretical understanding of the structural determinants of small entrepreneurship and the processes of economic incorporation of immigrants. This paper challenges this orthodoxy. It argues that it is important to assess the factors and processes that positively and negatively affect the formation of niches. This argument is corroborated by an analysis of the construction industry in the Netherlands. According to Waldinger (1995: 577), ‘construction represents the quintessential ethnic niche’, but immigrants in the Netherlands did not carve out a niche. This exceptional situation can be attributed to a sector-specific configuration of social, economic and institutional processes.     

Optimal dividend policy and growth option

We analyse the interaction between the dividend policy and the decision on investment in a growth opportunity of a liquidity constrained firm. This leads us to study a mixed singular control/optimal stopping problem for a diffusion that we solve quasi-explicitly by establishing a connection with an optimal stopping problem. We characterize situations where it is optimal to postpone the distribution of dividends in order to invest at a subsequent date in the growth opportunity. We show that uncertainty and liquidity shocks have an ambiguous effect on the investment decision.      

A DC programming heuristic applied to the logistics network design problem

This paper proposes a new heuristic method for the logistics network design and planning problem based on linear relaxation and DC (difference of convex functions) programming. We consider a multi-period, multi-echelon, multi-commodity and multi-product problem defined as a large scale mixed integer linear programming (MILP) model. The method is experimented on data sets of various size. The numerical results validate the efficiency of the heuristic for instances with up to several dozens facilities, 18 products and 270 retailers.     

The dynamics of innovation and horizontal differentiation

We study innovation in a dynamic stochastic discrete-time duopoly with endogenous horizontal differentiation. Innovation takes the form of a quality ladder; horizontal differentiation is Hotelling competition. We compute Markov-perfect equilibria and study the effects on long-run innovation of changes in taste heterogeneity (transport costs) and firms' costs of relocating products. Innovation rises as the industry's long-run position moves toward products that are permanently co-located in the space of horizontal tastes. A large enough fall in taste heterogeneity will raise long-run innovation, while more costly product relocation lowers innovation if taste heterogeneity is high, and raises it otherwise.     

Optimization of postal express line network under mixed driving pattern of trucks

Details about the movement of trucks on postal express lines are investigated to improve the performances of mail distribution. A mixed driving pattern of trucks is introduced to minimize the transportation cost of a postal express line network with a service level requirement. We formulate this problem as a mixed p meeting depots location with shipment scheduling problem and build a MINLP model. A two-level tabu search procedure based on shipment grouping method is developed. Through a series of computational experiments and sensitivity analysis on different instances, some managerial insights of the network under mixed driving pattern are revealed.     

有效需求波动、国有商业银行调整刚性与外资银行经营规模的选择

本文建立了一个有效需求水平不确定情况下的两阶段混合寡占博弈模型．前瞻性地讨论了国有商业银行的经营规模表现出调整刚性的情况下，外资银行经营规模的选择、其实际想要吸收的均衡存款量与选定经营规模之间所存在的关系．以及这种关系将会带来怎样的宏观经济与社会福利后果等问题。研究发现：（1）当实际中的有效需求水平越低时，外资银行经营规模的“产能”过剩；（2）当实际中的有效需求水平越高时，外资银行经营规模的“产能”不足。这一发现具有实施促进经济增长、有效控制居民收入差距政策方面的理论含义。     

Mixed up? that’s good for motivation

We show that career concerns can arise in the absence of ex ante uncertainty about an agent’s type, if his unobservable actions influence future productivity. Implementing effort in mixed strategies allows the principal to endogenously introduce uncertainty about the agent’s ex post productivity and generate reputational incentives. Creating such ambiguity can be optimal for the principal, even though this exposes the agent to additional risk and reduces output. This finding for an environment with imperfect commitment contrasts with standard agency models, where implementing mixed strategy actions typically is not optimal if pure strategies can also be implemented.     

Price competition during and after promotions

We provide a framework for setting regular prices and using promotional discounts in a duopoly where long‐term promotional effects are present and the firms' pricing and promotional strategies are common knowledge (e.g., as in online markets). We show that at equilibrium, the two firms may not promote and instead adopt an Everyday Low Price (EDLP) strategy. Consumers' tendency to stockpile promoted products, the level of brand loyalty and product differentiation, and the possibility of a postpromotional sales increase critically influence regular prices, price discount rates, and profits. Under some conditions consumer stockpiling intensifies promotional competition and reduces firms' profits while the possibility of attracting new consumers reduces the need to heavily promote and ensures better profits. Managerial implications are discussed. Copyright © 2007 ASAC. Published by John Wiley & Sons, Ltd.     

做市商制度对我国新三板市场的影响

场外交易市场建设初期,做市商制度在各国家及地区得到普遍应用。随着市场规模的扩大,交易制度逐步演变为混合性做市商制度。2014年我国新三板市场引入做市商制度,通过对市场整体以及协议转让、做市转让两类股票样本进行比较,文章认为在政策推动、市场主体积极参与等因素作用下,新三板市场整体规模、流动性均得到快速提高,做市商制度在流动性改善、价值发现等方面具有重要作用,挂牌公司具有较强的差异性对分层管理提出了现实需求。提高流动性仍然是新三板市场的重要任务之一,文章认为需要从制度、需求、供给、监管四个方面进行采取积极措施。