Creep resistant lead sheet by the D.M. process

Lead 68 ◽  
1969 ◽  
pp. 319-329 ◽  
Author(s):  
L.I. GOFF ◽  
G. HEWISH
Keyword(s):  
Lead Sheet

COMPARISON OF ELECTRON BEAM TRANSMISSION OF DIFFERENT ENERGIES WITH TWO DIFFERENT BLOCK MATERIALS AT DIFFERENT PLACEMENT POSITIONS WITHIN THE APPLICATOR

2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Navitha M ◽  
Jitendra Nigam ◽  
Silambarasan N S ◽  
Piyush Kumar ◽  
Pavan Kumar
Keyword(s):  
Electron Beam ◽  
Skin Surface ◽  
Parallel Plane ◽  
Percentage Transmission ◽  
Upper Level ◽  
Beam Transmission ◽  
Shielding Material ◽  
Different Thickness ◽  
Thick Lead ◽  
Lead Sheet

INTRODUCTION: Superficial tumors are treated with electron beams. Shielding blocks are used to conform to the shape of the tumor. These shielding blocks are usually kept at lower level of the applicator which is near the skin surface. The scattering property of electron may increase the surface dose which will increase with increasing electron energies. The purpose of this study is to compare electron beam transmission of different energies with two different block materials at different placement positions within the applicator. MATERIAL AND METHODS: Cerrobend alloy (50%bismuth, 26.7%lead, 13.3%tin and 10%cadmium) and 1mm thick lead sheets (94%lead, 6%alloy) in Varian Clinac2300C/D linear accelerator with electron energies 6,9,12,16 and 20MeVs using 10x10 applicator at 3 different holding levels was used. Measurements with RW3 Slab phantom (Water equivalent), PPC05 Parallel Plane Chamber, Dose 1 electrometer was done. The slab phantom 30x30x10 cm3 aligned with PPC05 Parallel Plane Chamber (at R85 of respective energies). Readings measured for open and block fields, for different thickness of shielding material, at different placement positions within the applicator. The percentage transmission calculated manually. RESULTS: Using electron energies 6,9,12,16, and 20MeVs respectively the transmission% were: with lead sheet 1mm thickness-2.48%,8.69%,16.05%, 28.03% and 39.50% at lower placement position, 1.19%,3.76%,7.75%,15% and 23.99% at centre placement and 0.96%,3.02%,6.15% and 20.27% for upper placement; with 2mm thickness-0.89%,1.62%,3.66%, 8.95% and 16.35% at lower level, 0.60%,1.28%,2.54%,5.74% and 10.72% at centre level and 0.57%,0.94%, 2.12%,4.85% and 9.22% at upper level; with 3mm thickness-0.80%,1.53%,2.88%,5.29% and 9.42% at lower position, 0.52%,1.25%,2.06%,4.03% and 7.36% at centre position and 0.51%, 0.90%,1.78%,3.66% and 6.43% at upper position; with 4mm thickness- 0.75%,1.40%, 2.71%,4.81% and 7.76% at lower level, 0.50%,1.18%,1.95%,3.68% and 6.31% at center level and 0.51%,0.80%, 1.70%,3.34% and 5.65% at upper level; with 5mm thickness-0.73%, 1.30%,2.57%,4.56% and 7.20% at lower level, 0.45%,1.06%,1.81%,3.48% and 5.68% at center level and 0.47%,0.79%,1.61%,3.13% and 5.24% at upper level. For Cerrobend material 5mm thickness, the transmission at lower level are 0.79%,1.50%,2.98%,5.58% and 10.39%, at center level are 0.52%,0.99%,2.09%,4.12% and 7.67% and at upper level are 0.49%,0.91%, 1.82%,3.75% and 6.90% for the energies 6,9,12,16 and 20 MeV’s respectively. CONCLUSION: There is not much difference in the transmission values at centre and upper levels so as to keep nearer the skin, the centre position in electron applicator may be optimum. Lead sheets can be used since easy to prepare especially for rectangular or square shapes.

Partial volume characteristics of ionization chambers in kilovoltage x-ray exposure measurements

2011 ◽  
Vol 11 (3) ◽  
pp. 184-188
Author(s):  
Syed F. Akber ◽  
Than S. Kehwar
Keyword(s):  
Ionization Chamber ◽  
Incident Radiation ◽  
Ionization Chambers ◽  
X Ray ◽  
Partial Volume ◽  
Spatial Response ◽  
Beam Output ◽  
Volume Characteristics ◽  
Made In ◽  
Lead Sheet

AbstractThe partial volume (spatial) response of four ionization chambers (Keithley) in kilovoltage X-ray beams, generated by the Philips Super 80CP X-ray unit, was assessed. The volume of the ionization chambers were of 10 cm3, 15 cm3, 150 cm3, and 600 cm3 used with Keithley electrometer Model 35040. The beam output was measured using a monitor chamber (Radcal 6.0 cm3) placed close to the collimator. The source to chamber distance was kept constant at 1 m. For the measurement of the response of ionization chambers of 15 cm3, 150 cm3, and 600 cm3, a slit of 2.0 mm width was made in a lead sheet of 3.2 mm thick and size of 30 × 30 cm2 and was placed on the ionization chamber. The measurements were made for 81 kVp, 400 mA, and 0.25 s and the slit was moved at an increment of 2.0 mm over the entire length of the chamber. For the measurements of the ionization chamber of 10 cm3 (CT chamber), the beams of 120 kVp, 200 mA and 0.2 s were generated, and a slit of 5 mm width was made in a similar lead sheet that was moved at an increment of 5.0 mm. From the result it appears that the sensitive volumes of the ionization chambers affect the response of the ionization chamber to incident radiation.

scholarly journals On the Adaptability of Recurrent Neural Networks for Real-Time Jazz Improvisation Accompaniment

2021 ◽  
Vol 3 ◽  
Author(s):  
Kosmas Kritsis ◽  
Theatina Kylafi ◽  
Maximos Kaliakatsos-Papakostas ◽  
Aggelos Pikrakis ◽  
Vassilis Katsouros
Keyword(s):  
Neural Networks ◽  
Real Time ◽  
Recurrent Neural Networks ◽  
Test Case ◽  
Jazz Improvisation ◽  
Artificial Agent ◽  
Separate Model ◽  
Subjective Evaluations ◽  
Refinement Process ◽  
Lead Sheet

Jazz improvisation on a given lead sheet with chords is an interesting scenario for studying the behaviour of artificial agents when they collaborate with humans. Specifically in jazz improvisation, the role of the accompanist is crucial for reflecting the harmonic and metric characteristics of a jazz standard, while identifying in real-time the intentions of the soloist and adapt the accompanying performance parameters accordingly. This paper presents a study on a basic implementation of an artificial jazz accompanist, which provides accompanying chord voicings to a human soloist that is conditioned by the soloing input and the harmonic and metric information provided in a lead sheet chart. The model of the artificial agent includes a separate model for predicting the intentions of the human soloist, towards providing proper accompaniment to the human performer in real-time. Simple implementations of Recurrent Neural Networks are employed both for modeling the predictions of the artificial agent and for modeling the expectations of human intention. A publicly available dataset is modified with a probabilistic refinement process for including all the necessary information for the task at hand and test-case compositions on two jazz standards show the ability of the system to comply with the harmonic constraints within the chart. Furthermore, the system is indicated to be able to provide varying output with different soloing conditions, while there is no significant sacrifice of “musicality” in generated music, as shown in subjective evaluations. Some important limitations that need to be addressed for obtaining more informative results on the potential of the examined approach are also discussed.

scholarly journals Music retrieval algorithms for the lead sheet problem

2005 ◽  
Vol 34 (4) ◽  
pp. 311-317 ◽  
Author(s):  
R. Clifford ◽  
R. Groult ◽  
C. S. Iliopoulos ◽  
D. Byrd
Keyword(s):  
Music Retrieval ◽  
Retrieval Algorithms ◽  
Lead Sheet

scholarly journals Minimising Defect Formation in Sand Casting of Sheet Lead: A DoE Approach

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 252
Author(s):  
Arun Prabhakar ◽  
Michail Papanikolaou ◽  
Konstantinos Salonitis ◽  
Mark Jolly
Keyword(s):  
Process Parameters ◽  
Surface Defects ◽  
Defect Formation ◽  
Casting Process ◽  
Sand Casting ◽  
Sand Cast ◽  
Factors Affecting ◽  
Screening Experiments ◽  
Traditional Manufacturing ◽  
Lead Sheet

Sand casting of lead sheet is a traditional manufacturing process used up to the present due to the special features of sand cast sheet such as their attractive sheen. Similarly to any casting process, sand casting of lead sheet suffers from the presence of surface defects. In this study, a surface defect type, hereby referred to as ‘grooves’, has been investigated. The focus has been laid on the identification of the main factors affecting defect formation in this process. Based on a set of screening experiments performed using Scanning Electron Microscopy (SEM) as well as the existing literature, a number of factors affecting the formation of such defects was identified and their corresponding significance was estimated using the Analysis of Variance (ANOVA) technique. The obtained results suggest that the most significant factor affecting defect formation in sand casting of lead sheet is the composition of the moulding mixture. Defect formation was also proven to be dependent on the sand grain fineness, the quality of the melt and some of the interactions between the aforementioned process parameters. Finally, an optimal set of process parameters leading to the minimisation of surface defects was identified.

scholarly journals A Harmonia tonal de Schoenberg: uma proposta para a análise, realização e composição de lead sheets

Per Musi ◽  
2013 ◽  
pp. 35-69 ◽  
Author(s):  
Fabiano Araújo ◽  
Fausto Borém
Keyword(s):  
Lead Sheet

As metodologias tradicionais do ensino de harmonia no jazz e outras músicas populares geralmente visam fornecer recursos para uma prática de improvisação, cuja abordagem é apenas homofônica. Propomos uma revisão e adaptação da teoria de harmonia tonal de SCHOENBERG (1999, 2004) como ferramenta de análise, realização e composição, a partir da lead sheet. Neste artigo de amplo escopo, (1) Conceitos Tonais (Monotonalidade, Movimento das Fundamentais, Notas Substitutas/Substituição, Transformação dos Acordes, Regiões e suas relações), (2) Funções Tonais (Geral, Específica e de Acordes Vagantes¹/de Função Múltipla) e (3) Contextos Tonais (Permutabilidade Maior-Menor, Enriquecimento da Cadência, Tonalidade Expandida, Tonalidade Flutuante, Tonalidade Suspensa) da análise harmônica tonal schoenberguiana são adaptados e explorados utilizando simbologias, teorias e práticas da música popular, e ilustrados com exemplos de duas canções instrumentais do Calendário do Som de Hermeto Pascoal: 9 de agosto de 1996 (PASCOAL, 2000a) e 14 de novembro de 1996 (PASCOAL, 2000b).

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