scholarly journals Physical Modeling, Algorithms, and Sound Synthesis: The NESS Project

2020 ◽  
Vol 43 (2-3) ◽  
pp. 15-30 ◽  
Author(s):  
Stefan Bilbao ◽  
Charlotte Desvages ◽  
Michele Ducceschi ◽  
Brian Hamilton ◽  
Reginald Harrison-Harsley ◽  
...  
Keyword(s):  
Physical Modeling ◽  
Large Scale ◽  
Algorithm Design ◽  
Sound Synthesis ◽  
Synthesis Methods ◽  
String Instruments ◽  
Time Stepping ◽  
Modal Synthesis ◽  
Percussion Instruments ◽  
Simplifying Assumptions

Synthesis using physical modeling has a long history. As computational costs for physical modeling synthesis are often much greater than for conventional synthesis methods, most techniques currently rely on simplifying assumptions. These include digital waveguides, as well as modal synthesis methods. Although such methods are efficient, it can be difficult to approach some of the more detailed behavior of musical instruments in this way, including strongly nonlinear interactions. Mainstream time-stepping simulation methods, despite being computationally costly, allow for such detailed modeling. In this article, the results of a five-year research project, Next Generation Sound Synthesis, are presented, with regard to algorithm design for a variety of sound-producing systems, including brass and bowed-string instruments, guitars, and large-scale environments for physical modeling synthesis. In addition, 3-D wave-based modeling of large acoustic spaces is discussed, as well as the embedding of percussion instruments within such spaces for full spatialization. This article concludes with a discussion of some of the basics of such time-stepping methods, as well as their application in audio synthesis.

scholarly journals Large-Scale Physical Modeling Synthesis, Parallel Computing, and Musical Experimentation: The NESS Project in Practice

2020 ◽  
Vol 43 (2-3) ◽  
pp. 31-47 ◽  
Author(s):  
Stefan Bilbao ◽  
James Perry ◽  
Paul Graham ◽  
Alan Gray ◽  
Kostas Kavoussanakis ◽  
...  
Keyword(s):  
Physical Modeling ◽  
Large Scale ◽  
Algorithm Design ◽  
Musical Instruments ◽  
Synthesis System ◽  
Professional Musicians ◽  
Musical Acoustics ◽  
Modeling Systems ◽  
Computational Resources ◽  
Theoretical Developments

Sound synthesis using physical modeling, emulating systems of a complexity approaching and even exceeding that of real-world acoustic musical instruments, is becoming possible, thanks to recent theoretical developments in musical acoustics and algorithm design. Severe practical difficulties remain, both at the level of the raw computational resources required, and at the level of user control. An approach to the first difficulty is through the use of large-scale parallelization, and results for a variety of physical modeling systems are presented here. Any progress with regard to the second difficulty requires, necessarily, the experience and advice of professional musicians. A basic interface to a parallelized large-scale physical modeling synthesis system is presented here, accompanied by first-hand descriptions of the working methods of five composers, each of whom generated complete multichannel pieces using the system.

scholarly journals A simple and efficient automated microvolume radiosynthesis of [18F]Florbetaben

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Ksenia Lisova ◽  
Jia Wang ◽  
Philip H. Chao ◽  
R. Michael van Dam
Keyword(s):  
Large Scale ◽  
Solid Phase ◽  
Acetonitrile Solution ◽  
Synthesis Methods ◽  
Pet Tracers ◽  
Molar Activity ◽  
Alternative Approaches ◽  
High Yields ◽  
Sufficient Concentration

Abstract Background Current automated radiosynthesizers are generally optimized for producing large batches of PET tracers. Preclinical imaging studies, however, often require only a small portion of a regular batch, which cannot be economically produced on a conventional synthesizer. Alternative approaches are desired to produce small to moderate batches to reduce cost and the amount of reagents and radioisotope needed to produce PET tracers with high molar activity. In this work we describe the first reported microvolume method for production of [18F]Florbetaben for use in imaging of Alzheimer’s disease. Procedures The microscale synthesis of [18F]Florbetaben was adapted from conventional-scale synthesis methods. Aqueous [18F]fluoride was azeotropically dried with K2CO3/K222 (275/383 nmol) complex prior to radiofluorination of the Boc-protected precursor (80 nmol) in 10 μL DMSO at 130 °C for 5 min. The resulting intermediate was deprotected with HCl at 90 °C for 3 min and recovered from the chip in aqueous acetonitrile solution. The crude product was purified via analytical scale HPLC and the collected fraction reformulated via solid-phase extraction using a miniature C18 cartridge. Results Starting with 270 ± 100 MBq (n = 3) of [18F]Fluoride, the method affords formulated product with 49 ± 3% (decay-corrected) yield,> 98% radiochemical purity and a molar activity of 338 ± 55 GBq/μmol. The miniature C18 cartridge enables efficient elution with only 150 μL of ethanol which is diluted to a final volume of 1.0 mL, thus providing a sufficient concentration for in vivo imaging. The whole procedure can be completed in 55 min. Conclusions This work describes an efficient and reliable procedure to produce [18F]Florbetaben in quantities sufficient for large-scale preclinical applications. This method provides very high yields and molar activities compared to reported literature methods. This method can be applied to higher starting activities with special consideration given to automation and radiolysis prevention.

A Survey of Modal Synthesis Methods

1971 ◽  
Author(s):  
Gary C. Hart ◽  
Walter C. Hurty ◽  
Jon D. Collins
Keyword(s):  
Synthesis Methods ◽  
Modal Synthesis

Modelling the dynamics of a minimal protocell container

2005 ◽  
Vol 4 (1) ◽  
pp. 81-91 ◽  
Author(s):  
Martin Nilsson Jacobi ◽  
Steen Rasmussen ◽  
Kolbjørn Tunstrøm
Keyword(s):  
Self Assembly ◽  
Large Scale ◽  
Lattice Gas ◽  
Three Dimensional ◽  
Initial Distribution ◽  
Energy Potential ◽  
Time Dynamics ◽  
Amphiphilic Molecules ◽  
Head Groups ◽  
Simplifying Assumptions

This paper is a discussion on how reaction kinetics and three-dimensional (3D) lattice simulations can be used to elucidate the dynamical properties of micelles as a possible minimal protocell container. We start with a general discussion on the role of molecular self-assembly in prebiotic and contemporary biological systems. A simple reaction kinetic model of a micellation process of amphiphilic molecules in water is then presented and solved analytically. Amphiphilic molecules are polymers with hydrophobic (water-fearing), e.g. hydrocarbon tail groups, and hydrophilic (water-loving) head groups, e.g. fatty acids. By making a few simplifying assumptions an analytical expression for the size distribution of the resulting micelles can be derived. The main part of the paper presents and discusses a lattice gas technique for a more detailed 3D simulation of molecular self-assembly of amphiphilic polymers in aqueous environments. Water molecules, hydrocarbon tail groups and hydrophilic head groups are explicitly represented on a three-dimensional discrete lattice. Molecules move on the lattice proportional to their continuous momentum. Collision rules preserve momentum and kinetic energy. Potential energy from molecular interactions are also included explicitly. The non-trivial thermodynamics of large-scale and long-time dynamics are studied. In this paper we specifically demonstrate how, from a random initial distribution, micelles are formed and grow until they destabilize and can divide. Eventually a steady state of growing and dividing micelles is formed. Towards the end of the paper we discuss the relevance of the presented results to the design of a minimal artificial protocell.

Physical Modeling for Selective Laser Sintering Process

2017 ◽  
Vol 17 (2) ◽  
Author(s):  
Arash Gobal ◽  
Bahram Ravani
Keyword(s):  
Physical Modeling ◽  
Large Scale ◽  
Selective Laser Sintering ◽  
Powdered Material ◽  
Laser Sintering ◽  
Industrial Applications ◽  
Transient Temperature ◽  
Sintering Process ◽  
Powder Bed ◽  
Selective Heating

The process of selective laser sintering (SLS) involves selective heating and fusion of powdered material using a moving laser beam. Because of its complicated manufacturing process, physical modeling of the transformation from powder to final product in the SLS process is currently a challenge. Existing simulations of transient temperatures during this process are performed either using finite-element (FE) or discrete-element (DE) methods which are either inaccurate in representing the heat-affected zone (HAZ) or computationally expensive to be practical in large-scale industrial applications. In this work, a new computational model for physical modeling of the transient temperature of the powder bed during the SLS process is developed that combines the FE and the DE methods and accounts for the dynamic changes of particle contact areas in the HAZ. The results show significant improvements in computational efficiency over traditional DE simulations while maintaining the same level of accuracy.

Large-scale physical modeling of broken solitary waves impacting elevated coastal structures

2022 ◽  
pp. 1-21
Author(s):  
Clemens Krautwald ◽  
Hajo Von Häfen ◽  
Peter Niebuhr ◽  
Katrin Vögele ◽  
David Schürenkamp ◽  
...  
Keyword(s):  
Solitary Waves ◽  
Physical Modeling ◽  
Large Scale ◽  
Coastal Structures
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