Loss Of Longitudinal Landau Damping in the LHC Injectors

A large number of collective instability mechanisms act on high-intensity beams. It is necessary to determine under what conditions the beam will remain stable. Space charge is the most fundamental mechanism and it represents the main intensity limitation in low-energy machines, while at high energy the inductive chamber impedance is often dominant. Landau damping provides a natural stabilizing mechanism against collective effects, if particles in the beam have a small spread S in their natural frequencies. The purpose of this report is to study the loss of Landau damping for the longitudinal plane via the âﾜSacherer formalismâ. Stability limits are calculated for several longitudinal beam distributions, including two types of flat bunches, which could be of interest to the LHC upgrade. Landau stability diagrams are computed and presented for different azimuthal modes. A general recipe is given for calculating the threshold intensity in the case of a capacitive impedance below transition or, equivalently, for a purely inductive impedance above transition. Results are finally applied to the case of the PS Booster, as an example of space-charge impedance below transition, and to the SPS, as an example of inductive impedance above transition

An Expert System for Mill Cutter and Cutting Parameters Selection

This paper discusses the selection of tools in milling processes. To carry out this research, it has been developed an expert system based on numerical methods. The expert system, chooses an appropriate tool, between a known set of candidate available cutters. The knowledge base is given by limiting the process variables. They are obtained taking into account, instabilities due to tool-work-piece interaction, which are called chatter vibration, and the power available in the spindle motor. Then, a tool cost model is designed as pattern, which is then used to decide the suitable cutting tool. Once the cutting tool is selected, the optimal cutting parameters are calculated. To obtain those parameters other two cost function are designed, which are dependent on the frequency and on time domain output signal properties. An example is presented to illustrate the method

Social economy and stakeholder theory, an integrative framework for socialization of the capitalism

In this article we set out to resolve the theoretical foundation of the Social Economy and its permeability with the capitalist economy by integrating the Social Economy paradigm with Stakeholder Theory, thus generating a reciprocal benefit. The alignment of resources and capabilities in accordance with social good, characteristic of the Social Economy, will furnish the ontological perspective of the Stakeholder Theory with a stronger grounding, distancing it from the instrumental perspective. It will also imbue it with a special concern for the social pole, frequently relegated in favour of other stakeholders. Rooting the Social Economy within the Stakeholder Theory makes at least three significant contributions to the former. Firstly, questioning Theory of Property Rights, secondly making it possible to give a systematic foundation to the concept of “families”, and thirdly setting off positive permeability between the Social and the Capitalist Economy. It enables progress in the socialisation of capitalism

Orthographic coding in illiterates and literates

Open Materials for the research article: Duñabeitia, J.A., Orihuela, K., & Carreiras, M. (2014). Orthographic coding in illiterates and literates. Psychological Science, 25(6), 1275-1280. Article abstract: We investigated how literacy modifies one of the mechanisms of the visual system that is essential for efficient reading: flexible position coding. To do so, we focused on the abilities of literates and illiterates to compare two-dimensional strings of letters (Experiment 1) and symbols (Experiment 2) in which the positions of characters had been manipulated. Results from two perceptual matching experiments revealed that literates were sensitive to alterations in characters’ within-string position and identity, whereas illiterates are almost blind to these changes. We concluded that letter-position coding is a mechanism that emerges during literacy acquisition and that the recognition of sequences of objects is highly modulated by reading skills. These data offer new insights about the manner in which reading acquisition shapes the visual system by making it highly sensitive to the internal structure of sequences of characters. The file contains all the different strings used in the experiments in the three critical conditions ("same", "different transposed" and "different replaced") made of two different types of characters (only letters or only symbols)