Experiments to shed light on the best way to use Iterated Local Search for a complex combinatorial problem

Iterated Local Search (ILS) is a popular metaheuristic search technique for use on combinatorial optimisation problems. As with most such techniques, there are many ways in which ILS can be implemented. The aim of this paper is to shed light on the best variants and choice of parameters when using ILS on a complex combinatorial problem with many objectives, by reporting on the results of an exhaustive set of experimental computer runs using ILS for a real-life sports scheduling problem. The results confirm the prevailing orthodoxy that a random element is ended for the ILS "kick", but also concludes that a non-random element can be valuable if it is chosen intelligently. Under these circumstances it is also found that the best ILS acceptance criterion to choose appears to depend upon the length of the run; for short runs, a high-diversification approach works best; for very long runs a high-intensification approach is best; while between these extremes, a more sophisticated approach using simulated annealing or threshold methods appears to be best

Observations of Ion Density and Temperature around the International Space Station During two Geomagnetic Storms

The International Space Station (ISS) is a low Earth orbit research facility and host to an international crew. Geomagnetic storms cause changes in the Earth’s magnetic field and affect the ion density and temperature in the ionosphere which could pose a hazard to ISS crew. This hazard is measured by the Floating Potential Measurement Unit (FPMU) which measures ion density, ion temperature, and the charge differential of the ISS relative to its surrounding environment. I analyzed data collected by Narrow Sweep Langmuir Probe for two storms in 2015. Ion density and temperature were affected by geomagnetic storms, but the effects were less than those found due to normal orbital conditions

Quick application/release nut with engagement indicator

A composite nut is shown which permits a fastener to be inserted or removed from either side with an indicator of fastener engagement. The nut has a plurality of segments, preferably at least three segments, which are internally threaded, spring loaded apart by an internal spring, and has detents on opposite sides which force the nut segments into operative engagements with a threaded member when pushed in and release the segments for quick insertion or removal of the nut when moved out. When the nut is installed, end pressure on one of the detents presses the nut segments into operative engagement with a threaded member where continued rotation locks the structure together with the detents depressed to indicate positive locking engagement of the nut. On removal, counterclockwise rotation of the nut relieves the endwise pressure on the detents, permitting internal springs to force the detents outward and allowing the nut segments to move outward and separate to permit quick removal of the fastener

Next Generation SHRM Research: From Covariation to Causation

[Excerpt] In response to the longstanding and repeated criticisms that HR does not add value to organizations, the past 10 years has seen a burgeoning of research attempting to demonstrate that progressive HR practices result in higher organizational performance. Huselid’s (1995)groundbreaking study demonstrated that a set of HR practices he referred to as High Performance Work Systems (HPWS) were related to accounting profits and market value of firms. Since then, a number of studies have shown similar positive relationships between HR practices and various measures of firm performance. While the studies comprising what I refer to as “first generation SHRM research” have added to what is becoming a more convincing body of evidence of the positive relationship between HR and performance, this body tends to lack sufficient data to demonstrate that the relationship is actually causal in the sense that HR practices, when instituted, lead to higher performance. This next generation of SHRM research will begin (and, in fact has begun) to focus on designing more rigorous tests of the hypothesis that employing progressive HRM systems actually results in higher organizational performance. This generation of research will focus on two aspects: demonstrating the HRM value chain, and proving causality as opposed to merely covariation

Two sided markets, competitive bottlenecks and exclusive contracts

We provide a framework for analyzing two-sided markets that allows for different degrees of product differentiation on each side of the market. When platforms are viewed as homogenous by sellers but heterogeneous by buyers, we show that “competitive bottlenecks” arise endogenously. In equilibrium, platforms do not compete directly for sellers, instead choosing to compete indirectly by subsidizing buyers to join. Sellers are left with none of the gains from trade. Despite this, it is sellers who choose to purchase from multiple platforms (multihome). Finally, the role of exclusive contracts to prevent multihoming is explored

Finding the far right online: an exploratory study of white supremacist websites

White supremacists and the Far Right political movement in the UK have, had considerable success in spreading their messages through Web sites. Some of these Web sites clearly contribute to an enabling environment for racially motivated violence in our towns and cities and possibly help to underpin also the rise of, and support for, the Far Right in the UK and elsewhere in Europe. From a position that acknowledges the enduring issue of white hegemony in Western societies, this paper provides a number of research-based recommendations for further research and future policy and practice in tackling white supremacist racial hatred on the Net

Theoretical and Empirical Challenges in Studying: The HR Practice - Firm Performance Relationship

Over the past 10 years a plethora of research has been conducted seeking to establish a relationship between human resource (HR) practices and firm performance. While this research has demonstrated promising results, a significant number of problems exist. This paper seeks to identify the theoretical and empirical challenges facing researchers who wish to further establish the impact of HR practices on firm performance. We conclude with some recommendations for future research in this area that might more accurately assess this relationship in ways that will be useful for both researchers and practitioners

The relationship between Revised Reinforcement Sensitivity Theory (rRST), handedness and indecision

Indecisiveness is an inability to make a decision, manifest across a number of behaviours. We explore the influence that both direction and strength of hand preference may have on this construct, examining it in relation to the revised Reinforcement Sensitivity Theory (rRST). Frost and Shows’ (1993) Indecisiveness Scale was administered to 328 undergraduates (221 females), alongside the Edinburgh Handedness Inventory (Oldfield, 1971) and Carver and White’s (1994) BIS/BAS scales. Simple correlations showed left-handers had a positive relationship between strength of handedness and BIS. In right-handers, strength and aversive indecision were positively correlated. Regression analysis demonstrated no significant relationship between hand strength and indecision, but that indecision was related to all three measures of rRST. Consistent with previous work, BIS was positively related to all indecision but particularly aversive, while BAS was negatively related to indecision but most strongly the avoidant category. We found that FFFS is more closely related to aversive than avoidant indecision. The relationship between rRST and indecision may be influenced by handedness; for right-handers the same pattern was found, but in left-handers BAS was not a significant predictor of indecision, BIS only predicted aversive indecision and FFFS predicted all three categories