The mixed evacuation problem

A dynamic network introduced by Ford and Fulkerson is a directed graph with capacities and transit times on its arcs. The quickest transshipment problem is one of the most fundamental problems in dynamic networks. In this problem, we are given sources and sinks. Then the goal of this problem is to find a minimum time limit such that we can send the right amount of flow from sources to sinks. In this paper, we introduce a variant of this problem called the mixed evacuation problem. This problem models an emergent situation in which people can evacuate on foot or by car. The goal is to organize such a mixed evacuation so that an efficient evacuation can be achieved. In this paper, we study this problem from the theoretical and practical viewpoints. In the first part, we prove the polynomial-time solvability of this problem in the case where the number of sources and sinks is not large, and also prove the polynomial-time solvability and computational hardness of its variants with integer constraints. In the second part, we apply our model to the case study of Minabe town in Wakayama prefecture, Japan.     

Online MapReduce processing on two identical parallel machines

In this work we investigate the online over-list MapReduce processing problem on two identical parallel machines, aiming at minimizing the makespan. Jobs are revealed one by one, and each job consists of one map task and one reduce task. The map task can be arbitrarily split and processed on both machines simultaneously, while the reduce task has to be processed on a single machine and it cannot be started unless the map task has been completed. We first show that the general case of the problem reduces to the classical two machine online scheduling model with an optimal competitive ratio of 3/2. For a special case where the map task is at least as long as the reduce task, we prove that no online algorithm can be less than 4/3-competitive. An optimal Greedy algorithm with a matching competitive ratio is proposed as well.     

Deterministic construction of compressed sensing matrices based on semilattices

A central problem in compressed sensing is the construction of sensing matrices. In this paper, we show how to construct sensing matrices by using semilattices, and give many examples of sensing matrices constructed from specific semilattices. Moreover, we show that the new construction for some examples with small parameters gives better sensing matrices compared with previously known constructions.     

Planning personnel retraining: column generation heuristics

Retraining of staff is a compulsory managerial function in many organisations and often requires planning for a large number of employees. The large scale of this problem and various restrictions on the resultant assignment to classes make this planning challenging. The paper presents a complexity analysis of this problem together with linear and nonlinear mathematical programming formulations. Three different column generation based optimisation procedures and a large neighbourhood search procedure, incorporating column generation, are compared by means of computational experiments. The experiments used data typical to large electricity distributors.     

An optimal Tate pairing computation using Jacobi quartic elliptic curves

This research paper proposes new explicit formulas to compute the Tate pairing on Jacobi quartic elliptic curves. We state the first geometric interpretation of the group law on Jacobi quartic curves by presenting the functions which arise in the addition and doubling. We draw together the best possible optimization that can be used to efficiently evaluate the Tate pairing using Jacobi quartic curves. They are competitive with all published formulas for Tate pairing computation using Short Weierstrass or Twisted Edwards curves. Finally we present several examples of pairing-friendly Jacobi quartic elliptic curves which provide optimal Tate pairing.     

Path cooperative games

Cooperative games provide an appropriate framework for fair and stable profit distribution in multiagent systems. In this paper, we study the algorithmic issues on path cooperative games that arise from the situations where some commodity flows through a network. In these games, a coalition of edges or vertices is successful if they establish a path from the source to the sink in the network, and lose otherwise. Based on dual theory of linear programming and the relationship with flow games, we provide the characterizations on the core, CS-core, least-core and nucleolus of path cooperative games, which implies all of these solution concepts are polynomial-time solvable for path cooperative games.     

Ownership structure,investors’ protection and corporate valuation: the effect of judicial system efficiency in family and non-family firms

Research on the effect of ownership structure on firm performance shows no convergent evidence concerning the sign and form of the above-mentioned relationship. Similarly, there is no homogeneous evidence documenting family ownership concentration is always positively or negatively correlated with firm value, or irrelevant. This paper analyses whether and how the de facto investor protection provided by the judicial system affects the relationship between corporate performance and ownership structure in 1314 firms operating in four European countries (Germany, France, Italy, and Spain) over a five-year period, 2010–2014. Moreover, we analyse whether judicial system efficiency influences if and how family firms in the controlling coalition collude for expropriating minority shareholders. Our findings show that the level of shareholder protection, derived from judicial efficiency, is relevant to the relationship between ownership structure and firm performance, thus corroborating literature in that institutional contexts matter in explaining such relations. The results suggest the need for more efficient external mechanisms of corporate governance to facilitate investment in equity capital, thus decreasing the country risk perceived by investors.     

Control or Autonomy? A Case Study of two Organizational Forms in the Zhangjiakou Internal Migrant Organization

Control often weakens autonomy in organizational theories. While many scholars focus on the paradox of control and autonomy, few pay attention to how an organization obtains both control and autonomy. By exploring Zhangjiakou Internal Immigrant Organization, this study finds two mechanisms can contribute to the balanced combination of control and autonomy. First, managers play ambidextrous official-merchant roles, which means superiors take both bureaucratic and autonomous management styles. Second, members have dual organizational goals for both political status and network support. In conclusion, the successful combination is shaped by the subjective interaction between the government, superior managers and subordinate members.     

The managerial power approach: Is it testable?

Journal of Management and Governance - The central hypothesis of the managerial power approach (MPA) states that power is the main driver of executive compensation. The positive impact of power on...     

A Probabilistic Framework for Risk Analysis of Widespread Flood Events: A Proof‐of‐Concept Study

This article presents a flood risk analysis model that considers the spatially heterogeneous nature of flood events. The basic concept of this approach is to generate a large sample of flood events that can be regarded as temporal extrapolation of flood events. These are combined with cumulative flood impact indicators, such as building damages, to finally derive time series of damages for risk estimation. Therefore, a multivariate modeling procedure that is able to take into account the spatial characteristics of flooding, the regionalization method top‐kriging, and three different impact indicators are combined in a model chain. Eventually, the expected annual flood impact (e.g., expected annual damages) and the flood impact associated with a low probability of occurrence are determined for a study area. The risk model has the potential to augment the understanding of flood risk in a region and thereby contribute to enhanced risk management of, for example, risk analysts and policymakers or insurance companies. The modeling framework was successfully applied in a proof‐of‐concept exercise in Vorarlberg (Austria). The results of the case study show that risk analysis has to be based on spatially heterogeneous flood events in order to estimate flood risk adequately.