String Crossings Research Articles

Performer’s Guide for Luigi Boccherini’s Cello Concerto No. 9 in B-flat Major from a Pedagogical Point of View

Cello Concerto No. 9 in B-flat Major by Luigi Boccherini, edited by German cellist and composer Friedrich Grützmacher, 
 is the bridge to lead amateur cellists to become professional, and it is essential for cellists in building a solid foundation before 
 exploring other standard concertos. Similar to the major concertos, including the Elgar Concerto in E Minor, the Schumann Cello 
 Concerto in A minor, or the Dvorak Cello Concerto in B minor, Boccherini’s Cello Concerto No. 9 contains virtuosic techniques, 
 such as various bow strokes, vibrato, thumb position, shifting, rapid string crossings and double stops. However, compared to the 
 major concertos, Boccherini’s concerto has an easier musical structure and a shorter music length, so it serves as a preparation 
 before continuing on to the more standard concertos. This paper will provide a pedagogical approach to the Boccherini’s ninth 
 concerto, along with analyzing other composers’ pedagogical approaches with supporting materials, such as etudes and cello 
 exercises written by string pedagogue and violinist Shinichi Suzuki, and Bohemian cellist and composer David Popper.

Torso and Bowing Arm Three-Dimensional Joint Kinematics of Elite Cellists: Clinical and Pedagogical Implications for Practice.

Elite cello playing requires complex and refined motor control. Cellists are prone to right shoulder and thoracolumbar injuries. Research informing injury management of cellists and cello pedagogy is limited. The aims of this study were to quantify the torso, right shoulder, and elbow joint movement used by elite cellists while performing a fundamental playing task, a C major scale, under two volume conditions. An eight degrees of freedom upper limb biomechanical model was applied to 3D motion capture data of the torso, upper arm, and forearm for 31 cellists with a mean experience of 19.4 yrs (SD 9.1). Two-factor ANOVA compared the joint positions between the four cello strings and two volume conditions. Significant (p<0.05) effects were found for either the string and/or volume conditions across all torso, shoulder, and elbow joint degrees of freedom. The torso was consistently positioned in left rotation from 5.0° (SD 5.6) at the beginning of the scale, increasing to 16.3° (5.5) at its apogee. The greatest mean shoulder flexion, internal rotation, and abduction joint angles were observed when playing at the tip of the bow on the top string (A): 107.2° (11.6), 59.1° (7.1), and -76.9° (15.7), respectively, during loud playing. Elite cellists use specific movement patterns to achieve string crossings and volume regulation during fundamental playing tasks. Implications of the static left-rotated torso posture and high degrees of combined shoulder flexion and internal rotation can be used to inform clinical and pedagogical practices.

From Rindler horizon to mini black holes at LHC

Recently researchers (A. Sepehri et al., Astrophys. Space Sci. 344, 79 (2013)) have considered the signature of superstring balls near mini black holes at LHC and calculate the information loss for these types of strings. Motivated by their work, we consider the evolution of events in high energy experiments from lower energies for which the Rindler horizon is formed to higher energies in which mini black holes and string balls are emerged. Extending the Gottesman and Preskill method to string theory, we find the information loss for excited strings “string balls” in mini black holes at LHC and calculate the information transformation from the collapsing matter to the state of outgoing Hawking radiation for strings. We come to the conclusion that information transformation for high energy strings is complete. Then the thermal distribution of excited strings near mini black holes at LHC is calculated. In order to obtain the total string cross section near black holes produced in proton-proton collision, we multiply the black hole production cross section by the thermal distribution of strings. It is observed that many high energy excited strings are produced near the event horizon of TeV black holes. These excited strings evaporate to standard model particles like Higgs boson and top quark at Hagedorn temperature. We derive the production cross section for these particles due to string ball decay at LHC and consider their decay to light particles like bottom quarks and gluons.

Framing holes within a loop hierarchy

We investigate the relation between nontrivial spatial concepts such as holes and string loops from a qualitative spatial reasoning perspective. In particular, we concentrate on a family of puzzles dealing with this kind of objects and explain how a loop formed in a string shows a similar behavior to a hole in an object, at least regarding the qualitative constraints it imposes on the solution of the puzzle. Unlike regular holes, however, we describe how string loops can be dynamically created and destroyed depending on the actions on the string. Furthermore, under a Knowledge Representation point of view, we provide a formalization that allows the different puzzle states to be described in terms of string crossings and loops, together with the actions that can be executed for a state transition and the complex effects they cause on the state representation. This implies the consideration of a formal representation of the side effects of actions that create or destroy string loops and the soundness of this representation with respect to the more general representation of string states in knot theory.

The Analysis of Fluid Pressure Impact on String Force and Deformation in Oil and Gas Wells

Fluid pressure is a crucial factor to tubular string strength and deformation in oil and gas wells, and it is the most difficult factor to deal with. When the string constrained by downhole tools, such as packers, action pattern of fluid on string is changed. Calculation methods of string stress and deformation given by engineering handbooks doesn’t distinguish these issues in detail. So mistakes are often made when these methods are used. Tangled concepts lead to large calculation error. In this paper, the influence of fluid pressure on string axial force and deformation, buoyancy treatment in packed condition, are discussed roundly both in vertical wells and directional wells. Practical calculating method of string axial force through the hook load is presented, and element buoyancy in different borehole trajectory is given. It is found that the traditional simplified buoyancy coefficient method, which is used to calculate string axial force and axial extension, can only be used in vertical wells with tubular string suspended freely, because in this condition buoyancy acts on the bottom of string. If the string is constrained by downhole tools, such as packer or anchor, buoyancy could not be treated as usual. In directional well the buoyancy not only changes string axial force but induces shear stress in string cross section. When calculating the influence of fluid on string, operation sequence and constraints from borehole and downhole tools should be considered comprehensively.

Coordination in fast repetitive violin-bowing patterns.

We present a study of coordination behavior in complex violin-bowing patterns involving simultaneous bow changes (reversal of bowing direction) and string crossings (changing from one string to another). Twenty-two violinists (8 advanced amateurs, 8 students with violin as major subject, and 6 elite professionals) participated in the experiment. We investigated the influence of a variety of performance conditions (specific bowing patterns, dynamic level, tempo, and transposition) and level of expertise on coordination behavior (a.o., relative phase and amplitude) and stability. It was found that the general coordination behavior was highly consistent, characterized by a systematic phase lead of bow inclination over bow velocity of about 15° (i.e., string crossings were consistently timed earlier than bow changes). Within similar conditions, a high individual consistency was found, whereas the inter-individual agreement was considerably less. Furthermore, systematic influences of performance conditions on coordination behavior and stability were found, which could be partly explained in terms of particular performance constraints. Concerning level of expertise, only subtle differences were found, the student and professional groups (higher level of expertise) showing a slightly higher stability than the amateur group (lower level of expertise). The general coordination behavior as observed in the current study showed a high agreement with perceptual preferences reported in an earlier study to similar bowing patterns, implying that complex bowing trajectories for an important part emerge from auditory-motor interaction.

Auditory perception of note transitions in simulated complex bowing patterns

Recent motion-capture measurements of violin bowing revealed an interesting coordination behavior in fast repetitive bowing patterns involving bow changes and string crossings; bow changes were consistently lagging behind string crossings, and the relative timing appeared to be an integral part of the bow-movement patterns. The aim of the current study was to investigate if there might be a perceptual explanation for the observed coordination behavior. For this purpose a virtual violin was used, controlled by simulated bowing gestures. A simplified coordination model is presented, which was implemented to allow real-time control of complex bowing patterns. This synthesis approach was employed in a perceptual experiment in which the participants were asked to optimize the sound by adjusting a slider controlling the main coordination parameters. It was found that the resulting coordination patterns were similar to those observed in performance, implying that complex bowing trajectories for an important part emerge from auditory-motor interaction. Further analysis of the responses shed light on temporal and spatial constraints of the simulated gestures associated with the note transitions. The results raise interesting questions with regard to auditory-motor interaction in complex instrumental control gestures.

Perception and production of complex bowing movements in violin performance

In bowed-string instruments, the primary function of bowing movements is to control the parameters that govern the stick-slip interaction between the bow and the string, giving the performer control of the sound. Not less importantly, bowing movements have to be planned ahead in order to anticipate future events. In fast, repetitive bowing movements involving string crossings and bow changes the primary and anticipatory movements become integrated, forming an overall, in the simplest case circular movement pattern. The relative timing of string crossings and bow changes is an inherent property of the shape of these patterns, which therefore has an important influence on the quality of the note transitions. We will present two complementary studies that provide insight in this coordination phenomenon. A perceptual study has been conducted using a virtual violin, in which the participants could influence the relative timing between string crossings and bow changes by a simple slider, giving insight in the perception of such transitions and typical temporal constraints. Analyses of bowing movements show in detail how the coordination is realized in performance, and how the performer adapts her/his movement patterns to performance constraints, such as tempo and dynamic level.

Dynamic Response of the Casing String in Seabed Soil for Deepwater Drilling

The marine riser has transfer dynamic cyclic load to the top of casing string when deepwater drilling operating. Considering with the nonlinear characteristics of seabed soil, the variable string cross section, and the axial load on the top of string, a dynamic differential equation of casing string below mud line and its numerical solution were established. Results illustrate that, the lateral displacement, the bending moment, and the shear of the casing string are not equal when lateral dynamic cyclic loading achieves amplitude due to the soil hysteresis effect. The diameter and wall thickness of conductor have less affect to string vibration frequency, cannot adjust the string natural frequency by adjusting these parameters. The natural frequency of casing string in sand is bigger than it in clay. The undrained shear strength of soil has great effect on the natural frequency of casing string in clay. The lateral displacement amplitude is highest when the vibration frequency of casing string at its natural frequency.

Confining string and its widening inHP1embedding approach

The structure of the confining string in terms of the topological charge density and the action density is studied in $SU(2)$ Yang-Mills theory on the lattice using the ${\mathrm{HP}}^{1}$ $\ensuremath{\sigma}$-model embedding approach. We find that the confining flux tube noticeably suppresses both the topological charge and the action densities. Beyond the string formation length the string cross section in terms of these quantities is well described by a Gaussian profile. In both cases the squared string width is found to be a logarithmic function of the string length confirming the L\"uscher widening of the chromoelectric string. Characteristic string scales in terms of the topological and action densities are estimated as well.

Quality aspects of violin bows

The string player’s test of a bow includes four major aspects: (1) the bow should be ‘‘well balanced’’ with an appropriate total weight; (2) the bow should have a good grip of the string over the entire length of the bow stroke; (3) the ‘‘timbre of the bow’’ should be pleasing; and (4) the bow should bounce easily in advanced bowing patterns like rapid spiccato and ricochet. A poor bow will: fatigue the player by demanding too much physical effort (in particular in string crossings); tend to lose the grip of the string when approaching the tip; disguise the tonal quality of a fine instrument; and be sluggish and scratchy in rapid bouncing sequences. Some plausible physical properties which govern these four quality aspects will be presented, focusing on the last, the bouncing bow. [Work supported by School of Electrical Engineering, Royal Institute of Technology, Stockholm.]

String crossings [computer graphics

When the author was about 10 years old, he completed a project which involved driving little brass nails into a piece of wood so that they were equally spaced around a circle, and then winding shiny metal wire between every pair of nails. The result was a shiny spider's web of wire-it was an algorithm for making an aesthetic visual piece. Years later, when he started to learn computer graphics, he programmed up these string art creations on vector storage tubes and plotters, mixing colors and changing line widths. Then recently, an artist friend (Dan Robbins) mentioned that he was planning a sculpture that involved a similar kind of design. Part of his sculpture involved placing objects at the intersections of pairs of strings. He wanted to plan part of the sculpture in advance and asked if there was a way to determine how many strings were necessary to get a desired number of intersections. The article starts with an answer to Dan's question. It also explores some other questions derived from these simple but elegant little string art patterns. These lovely little geometric patterns lead to numerical patterns every bit as graceful and aesthetically pleasing.

Bowing Figures: An Analysis of String Crossings

Bowing Figures: <i>An Analysis of String Crossings</i>

Utilizing power-information criteria for investigating the quality of string transducers

1. The application of the basic relationships of the measurement information theory make it possible to obtain a combined evaluation of the string frequency transducers' quality. 2. The utilization of the power sensitivity threshold ensures objective recommendations in selecting string transducers' parameters. 3. The efficiency of string transducers rises with the raising of the ratio of the elasticity modulus to the density of the material and the reduction of the string length and cross section. 4. The limitation of the power sensitivity threshold at a given development level serves to find the possibility of producing string transducers for measuring various physical quantities.