Isolation and identification of mycobacteria responsible for tuberculosis of dromedaries in Algeria

peer reviewe

Thermal Analysis of SRF Cavity Couplers Using Parallel Multi physics Tool TEM3P

SLAC has developed a multi-physics simulation code TEM3P for simulating integrated effects of electromagnetic, thermal and structural loads. TEM3P shares the same software infrastructure with SLAC's parallel finite element electromagnetic codes, thus enabling all physics simulations within a single framework. The finite-element approach allows high-fidelity, high-accuracy simulations and the parallel implementation facilitates large-scale computation with fast turnaround times. In this paper, TEM3P is used to analyze thermal loading at coupler end of the JLAB SRF cavity

Policy-making tool for optimization of transit priority lanes in urban network

Transit improvement is an effective way to relieve traffic congestion and decrease greenhouse gas emissions. Improvement can be in the form of new facilities or giving on-road priority to transit. Although construction of off-road mass transit is not always viable, giving priority to transit can be a low-cost alternative. A framework is introduced for optimization of bus priority at the network level. The framework identifies links on which a bus lane should be located. Allocation of a lane to transit vehicles would increase the utility of transit, although this can be a disadvantage to auto traffic. The approach balances the impact on all stakeholders. Automobile advocates would like to increase traffic road space, and the total travel time of users and total emissions of the network could be reduced by a stronger priority scheme. A bilevel optimization is applied that encompasses an objective function at the upper level and a mode choice, a traffic assignment, and a transit assignment model at the lower level. The proposed optimization helps transport authorities to quantify the outcomes of various strategies of transit priority. A detailed sensitivity analysis is carried out on the relative weight of each factor in the objective function. The proposed framework can also be applied in the context of high-occupancy-vehicle lanes and heavy-vehicle priority lanes

Computational Science Research in Support of Petascale Electromagnetic Modeling

Computational science research components were vital parts of the SciDAC-1 accelerator project and are continuing to play a critical role in newly-funded SciDAC-2 accelerator project, the Community Petascale Project for Accelerator Science and Simulation (ComPASS). Recent advances and achievements in the area of computational science research in support of petascale electromagnetic modeling for accelerator design analysis are presented, which include shape determination of superconducting RF cavities, mesh-based multilevel preconditioner in solving highly-indefinite linear systems, moving window using h- or p- refinement for time-domain short-range wakefield calculations, and improved scalable application I/O

Analysis of the Cause of High External Q Modes in the JLab High Gradient Prototype Cryomodule Renascence

The Renascence cryomodule [1] installed in CEBAF in 2007 consists of 8 cavities as shown in Figure 1. The first three cavities (No.1-No.3) in the upstream end are of the Low Loss (LL) shape design, and the remaining 5 cavities (No.4-No.8) on the beam downstream end are the High Gradient (HG) shape design. The fundamental power couplers (FPCs) are the rectangular waveguides, and the little cylindrical structures are the HOM couplers. The locations of the FPC in the last four cavities are mirrored about the beam z axis. Cavities No.4 and No.5 form a back-to-back cavity pair. Among the HG cavities installed in the Renascence cryomodule, the only identifiable difference from their fabrication documentation is that cavity No.5 received an extra EBW pass on one equator weld, specifically cell 5. The non-uniform mechanical tuning required to compensate the fundamental mode tune and flatness for the extra shrinkage of this cell is believed to contribute the most significant differences from the other HG cavities. Beam based instability studies on this cryomodule in CEBAF have shown a significant beam breakup (BBU) threshold current reduction, well below design value. Frequency spectrum peaked by the off-sided beam power indicated the cause is due to abnormal high Q modes in the cavity No.5. Measured beam off-axis position at the cavity No.5 does not correspond to the shunt impedances calculated for an ideal cavity. Low power RF measurements have identified that the problematic modes are in the second dipole band (TM110 like). Three of the modes have external Qs two orders magnitude higher than the others, while the rest of modes in the first two dipole bands are normal in terms of the design values. The cause of this abnormality and the future impact on the BBU was not able to be resolved due to the limitations of information that can be obtained from the measurements. It is important to understand the cause of this abnormality so that effective QA/QC measures can be implemented to avoid such problem in the final upgrade design and manufacture. The goal of this work is to utilize advanced simulation tools to understand the high external Q (Q{sub ext}) problem observed in the Renascence cryomodule. In the past years, SLAC has built a set of state-of-the-art advanced simulation tools based on finite-element unstructured meshes and parallel computation implementations on supercomputers [2, 3]. The codes are capable of simulating large complex RF systems with unprecedented resolution and turnaround time. They have been successfully applied to many existing and future accelerator R&D projects to improve the machine performance and to optimize the designs. These tools are essential to perform accurate full system analyses such as the JLab's SRF cavities. We will use the simulation results and the data from the RF measurements to gain a better understanding of the cavity performance and tolerance issues and provide a solid foundation to do the BBU simulation and prediction for the 12GeV Upgrade project by using JLab's BBU codes. In this report, we will focus on the following two main tasks: (1) Ideal cavity simulation--to evaluate the effectiveness of the damping by the higher-order-mode (HOM) couplers, and search for possible trapped modes in a back-to-back cavity pair (e.g. cavity No.4 & No.5). (2) Abnormal cavity study--to understand the cause of the high Q{sub ext} modes in cavity No.5 using an advanced Shape Determination Tool

Design and Optimization of Large Accelerator Systems through High-Fidelity Electromagnetic Simulations

SciDAC1, with its support for the 'Advanced Computing for 21st Century Accelerator Science and Technology' (AST) project, witnessed dramatic advances in electromagnetic (EM) simulations for the design and optimization of important accelerators across the Office of Science. In SciDAC2, EM simulations continue to play an important role in the 'Community Petascale Project for Accelerator Science and Simulation' (ComPASS), through close collaborations with SciDAC CETs/Institutes in computational science. Existing codes will be improved and new multi-physics tools will be developed to model large accelerator systems with unprecedented realism and high accuracy using computing resources at petascale. These tools aim at targeting the most challenging problems facing the ComPASS project. Supported by advances in computational science research, they have been successfully applied to the International Linear Collider (ILC) and the Large Hadron Collider (LHC) in High Energy Physics (HEP), the JLab 12-GeV Upgrade in Nuclear Physics (NP), as well as the Spallation Neutron Source (SNS) and the Linac Coherent Light Source (LCLS) in Basic Energy Sciences (BES)