Supply chain management: An opportunity for metaheuristics

In today s highly competitive and global marketplace the pressure onorganizations to find new ways to create and deliver value to customersgrows ever stronger. In the last two decades, logistics and supply chainhas moved to the center stage. There has been a growing recognition thatit is through an effective management of the logistics function and thesupply chain that the goal of cost reduction and service enhancement canbe achieved. The key to success in Supply Chain Management (SCM) requireheavy emphasis on integration of activities, cooperation, coordination andinformation sharing throughout the entire supply chain, from suppliers tocustomers. To be able to respond to the challenge of integration there isthe need of sophisticated decision support systems based on powerfulmathematical models and solution techniques, together with the advancesin information and communication technologies. The industry and the academiahave become increasingly interested in SCM to be able to respond to theproblems and issues posed by the changes in the logistics and supply chain.We present a brief discussion on the important issues in SCM. We then arguethat metaheuristics can play an important role in solving complex supplychain related problems derived by the importance of designing and managingthe entire supply chain as a single entity. We will focus specially on theIterated Local Search, Tabu Search and Scatter Search as the ones, but notlimited to, with great potential to be used on solving the SCM relatedproblems. We will present briefly some successful applications.

Do market conditions affect preferences? Evidence from experimental markets with excess supply and excess demand

We study whether people's preferences in an unbalanced market are affected by whether they are on the excess supply side or the excess demand side of the market. Our analysis is based on the comparison of behavior between two types of experimental gift exchange markets, which vary only with respect to whether first or second movers are on the long side of the market. The direction of market imbalance could influence subjects' motivation, as second movers, workers, might react differently to favorable actions by first movers, firms, in the two cases. Our data show strong deviations from the standard game-theoretic prediction. However, we only find secondary treatment effects. First movers are not more generous when they are in excess supply and second movers do not respond less favorably when they are in excess demand. Competition has only minor psychological effects in our data.

Supply side interventions and redistribution

In this paper we study the welfare impact of alternative tax schemes on laborand capital. We evaluate the e_ect of lowering capital income taxes on thedistribution of wealth in a model with heterogeneous agents, restricting ourattention to policies with constant tax rates.We calibrate and simulate the economy; we find that lowering capital taxeshas two effects: i) it increases effciency in terms of aggregate production, andii) it redistributes wealth in favor of those agents with a low wage/wealth ratio.We find that the redistributive effect dominates, and that agents with a lowwage wealth ratio would experience a large loss in utility if capital income taxeswere eliminated.

E-supply chain management: Review, implications and directions for future research

This paper analyses the interaction of two topics: Supply Chain Management (SCM) andInternet. Merging these two fields is a key area of concern for contemporary managers andresearchers. They have realized that Internet can enhance SCM by making real timeinformation available and enabling collaboration between trading partners. The aim of thispaper is to define e-SCM, analyze how research in this area has evolved during the period1995-2003 and identify some lines of further research. To do that a literature review inprestigious academic journals in Operations Management and Logistics has beenconducted.

Incomplete markets, labor supply and capital accumulation

In this paper we explore the accumulation of capital in the presence oflimited insurance against idiosyncratic shocks, borrowing constraintsand endogenous labor supply. As in the exogenous labor supply case(e.g. Aiyagari 1994, Huggett 1997), we find that steady states arecharacterized with an interest rate smaller than the rate of timepreference. However,wealsofind that when labor supply is endogenous thepresence of uncertainty and a borrowing limit are not enough to giverise to aggregate precautionary savings .

Female labour supply in Spain: The importance of behavioural assumptions and unobserved heterogeneity specification

We estimate four models of female labour supply using a Spanish sampleof married women from 1994, taking into account the complete form of theindividual s budget set. The models differ in the hypotheses relating tothe presence of optimisation errors and/or the way non-workers contributeto the likelihood function. According to the results, the effects of wagesand non-labour income on the labour supply of Spanish married women dependon the specification used. The model which has both preference andoptimisation errors and allows for both voluntarily and involuntarilyunemployed females desiring to participate seems to better fit the evidencefor Spanish married women.

The impact of tax credits on labour supply

One of the principle aims of the Working Families' Tax Credit in the UK was to increase the participation of single mothers. The literature to date concludes there was approximately a five-percentage-point increase in employment of single mothers. The differences-in-differences methodology that is typically used compares single mother with single women without children. However, the characteristics of these groups are very different, and change over time in relative covariates are likely to violate the identifying assumption. We find that when we control for differential trends between women with and without children, the employment effect of the policy falls significantly. Moreover, the effect is borne solely by those working full-time (30 hours or more), while having no effect on inducing people into the labor market from inactivity. Looking closely at important covariates over time, we can see sizeable changes in the relative returns to employment between the treatment and control groups.

Immigration, family responsibilities and the labor supply of skilled native women

This paper investigates the effects of Spain s large recent immigration wave on thelabor supply of highly skilled native women. We hypothesize that female immigration led to an increase in the supply of affordable household services, such as housekeeping and child or elderly care. As a result, i) native females with high earnings potential were able to increase their labor supply, and ii) the effects were larger on skilled women whose labor supply was heavily constrained by family responsibilities. Our evidence indicates that over the last decade immigration led to an important expansion in the size of the household services sector and to an increase in the labor supply of women in high-earning occupations (of about 2 hours per week). We also find that immigration allowed skilled native women to return to work sooner after childbirth, to stay in the workforce longer when having elderly dependents in the household, and to postpone retirement. Methodologically, we show that the availability of even limited Registry data makes it feasible to conduct the analysis using quarterly household survey data, as opposed to having to rely on the decennial Census.

Supply chain management as a competitive advantage in the Spanish grocery sector

Adversarial relationships have long dominated business relationships,but Supply Chain Management (SCM) entails a new perspective. SCM requiresa movement away from arms-length relationships toward partnership stylerelations. SCM involves integration, co-ordination and collaborationacross organisations and throughout the supply chain. It means that SCMrequires internal (intraorganisational) and external (interorganisational)integration. This paper analyses the relationship between internal andexternal integration processes, their effect on firms performance andtheir contribution to the achievement of a competitive advantage.Performance improvements are analysed through costs, stock out and leadtime reductions. And, the achievement of a better competitive positionis measured by comparing the firm s performance with its competitors performance. To analyse this, an empirical study has been conducted inthe Spanish grocery sector.

Systematic study of the static electrical properties of the CO molecule: influence of the basis set size and correlation energy

The influence of the basis set size and the correlation energy in the static electrical properties of the CO molecule is assessed. In particular, we have studied both the nuclear relaxation and the vibrational contributions to the static molecular electrical properties, the vibrational Stark effect (VSE) and the vibrational intensity effect (VIE). From a mathematical point of view, when a static and uniform electric field is applied to a molecule, the energy of this system can be expressed in terms of a double power series with respect to the bond length and to the field strength. From the power series expansion of the potential energy, field-dependent expressions for the equilibrium geometry, for the potential energy and for the force constant are obtained. The nuclear relaxation and vibrational contributions to the molecular electrical properties are analyzed in terms of the derivatives of the electronic molecular properties. In general, the results presented show that accurate inclusion of the correlation energy and large basis sets are needed to calculate the molecular electrical properties and their derivatives with respect to either nuclear displacements or/and field strength. With respect to experimental data, the calculated power series coefficients are overestimated by the SCF, CISD, and QCISD methods. On the contrary, perturbation methods (MP2 and MP4) tend to underestimate them. In average and using the 6-311 + G(3df) basis set and for the CO molecule, the nuclear relaxation and the vibrational contributions to the molecular electrical properties amount to 11.7%, 3.3%, and 69.7% of the purely electronic μ, α, and β values, respectively

Calculation of radio electrical coverage in Medium-Wave Frequencies

The aim of this project is to accomplish an application software based on Matlab to calculate the radioelectrical coverage by surface wave of broadcast radiostations in the band of Medium Wave (WM) all around the world. Also, given the location of a transmitting and a receiving station, the software should be able to calculate the electric field that the receiver should receive at that specific site. In case of several transmitters, the program should search for the existence of Inter-Symbol Interference, and calculate the field strenght accordingly. The application should ask for the configuration parameters of the transmitter radiostation within a Graphical User Interface (GUI), and bring back the resulting coverage above a map of the area under study. For the development of this project, it has been used several conductivity databases of different countries, and a high-resolution elevation database (GLOBE). Also, to calculate the field strenght due to groundwave propagation, it has been used ITU GRWAVE program, which must be integrated into a Matlab interface to be used by the application developed.

Lobbying, political competition, and local land supply: recent evidence from Spain

We analyze whether local land supply is influenced by the degree of political competition, and interpret the findings as being indicative of the influence wielded by land development lobbies. We use a new database including both political and land supply data for more than 2,000 Spanish municipalities for the period 2003-2007. In Spain, land use policies are largely a local responsibility with municipalities having periodically to pass compre- hensive land use plans. The main policy variable in these plans, and the one analyzed here, is the amount of land classified for potential development. We measure local political competition as the margin of victory of the incumbent government. We instrument this variable using the number of votes obtained by parties represented in local government when standing at the first national legislative elections following the re-establishment of democracy, and the number of votes they actually obtained regionally at the national legislative elections. The results indicate that stiffer political competition does indeed reduce the amount of new land designated for development. This effect is found to be most marked in suburbs, in towns with a high percent of commuters and homeowners, and in municipalities governed by the left.

Electrical transport quantum effects in the In0.53Ga0.47As/In0.52Al0.48As heterostructure on silicon

Electrical transport in a modulation doped heterostructure of In0.53Ga0.47As/In0.52Al0.48As grown on Si by molecular beam epitaxy has been measured. Quantum Hall effect and Subnikov¿De Haas oscillations were observed indicating the two¿dimensional character of electron transport. A mobility of 20¿000 cm2/V¿s was measured at 6 K for an electron sheet concentration of 1.7×1012 cm¿2. Transmission electron microscopy observations indicated a significant surface roughness and high defect density of the InGaAs/InAlAs layers to be present due to the growth on silicon. In addition, fine¿scale composition modulation present in the In0.53Ga0.47As/In0.52Al0.48As may further limit transport properties.

Nanoscale electrical conductivity of the purple membrane monolayer

Nanoscale electron transport through the purple membrane monolayer, a two-dimensional crystal lattice of the transmembrane protein bacteriorhodopsin, is studied by conductive atomic force microscopy. We demonstrate that the purple membrane exhibits nonresonant tunneling transport, with two characteristic tunneling regimes depending on the applied voltage (direct and Fowler-Nordheim). Our results show that the purple membrane can carry significant current density at the nanometer scale, several orders of magnitude larger than previously estimated by macroscale measurements.

Lobbying, political competition, and local land supply: recent evidence from Spain

We analyze whether local land supply is influenced by the degree of political competition, and interpret the findings as being indicative of the influence wielded by land development lobbies. We use a new database including both political and land supply data for more than 2,000 Spanish municipalities for the period 2003-2007. In Spain, land use policies are largely a local responsibility with municipalities having periodically to pass compre- hensive land use plans. The main policy variable in these plans, and the one analyzed here, is the amount of land classified for potential development. We measure local political competition as the margin of victory of the incumbent government. We instrument this variable using the number of votes obtained by parties represented in local government when standing at the first national legislative elections following the re-establishment of democracy, and the number of votes they actually obtained regionally at the national legislative elections. The results indicate that stiffer political competition does indeed reduce the amount of new land designated for development. This effect is found to be most marked in suburbs, in towns with a high percent of commuters and homeowners, and in municipalities governed by the left.