Cryogenics for Superconductors: Refrigeration, Delivery, and Preservation of the Cold

Applications in superconductivity have become widespread, enabled by advancements in cryogenic engineering. In this paper, the history of cryogenic refrigeration, its delivery, its preservation and the important scientific and engineering advancements in these areas in the last 100 years will be reviewed, beginning with small laboratory dewars to very large scale systems. The key technological advancements in these areas that enabled the development of superconducting applications at temperatures from 4 to 77 K are identified. Included are advancements in the components used up to the present state-of-the-art in refrigeration systems design. Viewpoints as both an equipment supplier and the end-user with regard to the equipment design and operations will be presented. Some of the present and future challenges in these areas will be outlined. Most of the materials in this paper are a collection of the historical materials applicable to these areas of interest

Améliorer les dispositifs de concertation des projets : résumé des propositions

Réunis en groupes correspondant aux projets dans lesquels ils interviennent, les participants ont fait des propositions visant à rendre plus satisfaisantes et plus durables les relations entre partenaires des quatre projets analysés. Les améliorations proposées par les groupes reposent sur une formalisation accrue et sur une plus grande coordination des acteurs sur le terrain. (Résumé d'auteur

Nilai Karies Gigi Anak Kelas 1 dan Kelas 6 Sekolah Dasar di Salah Satu Puskesmas Kabupaten Tangerang (Pemeriksa Dokter Umum, Dokter Gigi dan Perawat Gigi)

. Dental and oral health status as expressed in dental caries are important problems, health nearly 90% of Indonesian suffered dental caries. The common cause of denial caries is poor oral hygiene, as it leads to make plaque accumulation containing various bacteria. Tendency of plaque formation exists in every individual in every ege. Objective of the study : To get the format and procedure of examination at dental carries by comparating the examination results between general practitioners and dentists, dentists and dental nurses, and general practitioners and dental nurses. The study took ten month, by diagnostic test design and conducted in a sub district primary health centre in Tangerang. The study was equivalent by ten general practitioners, ten dentists and ten dental nurses by using mouth mirrors. The member of respondents were 60 persons from both genders with 6 and 12 years age and who lived in Tangerang. They included about 30 children from first standard of primary school and 30 children from 6 ' class of primary school at six years and 12 years old. They were from one of the government schools is the district of Tangerang. The collection of data had been done by examining the dental carries of 60 students by ten general practitioners, ten dentists, and ten dental nurses. They participated in this study after going informed consent. Data analyses were using t test and wilcoxon test by SPSS 11.5. The result of this study showed D (decay), M (missing), F (filling) and DMF-T with variation. Actually general Practitioners can do same the examination as dentists and dental nurses, put general practitioners sufficiently understand the importance of M (missing) and F (Filling)

Commissioning of the Liquid Nitrogen Thermo-Siphon System for NASA-JSC Chamber-A

NASA's Space Environment Simulation Laboratory's (SESL) Chamber A, located at the Johnson Space Center in Houston Texas has recently implemented major enhancements of its cryogenic and vacuum systems. The new liquid nitrogen (LN2) thermo-siphon system was successfully commissioned in August of 2012. Chamber A, which has 20 K helium cryo-panels (or shrouds ) which are shielded by 80 K nitrogen shrouds, is capable of simulating a deep space environment necessary to perform ground testing of NASA s James Webb Space Telescope (JWST). Chamber A s previous system used forced flow LN2 cooling with centrifugal pumps, requiring 200,000 liters of LN2 to cool-down and consuming 180,000 liters per day of LN2 in steady operation. The LN2 system did not have the reliability required to meet the long duration test of the JWST, and the cost estimate provided in the initial approach to NASA-JSC by the sub-contractor for refurbishment of the system to meet the reliability goals was prohibitive. At NASA-JSC's request, the JLab Cryogenics Group provided alternative options in 2007, including a thermo-siphon, or natural flow system. This system, eliminated the need for pumps and used one tenth of the original control valves, relief valves, and burst disks. After the thermo-siphon approach was selected, JLab provided technical assistance in the process design, mechanical design, component specification development and commissioning oversight, while the installation and commissioning operations of the system was overseen by the Jacobs Technology/ESC group at JSC. The preliminary commissioning data indicate lower shroud temperatures, 70,000 liters to cool-down and less than 90,000 liters per day consumed in steady operation. All of the performance capabilities have exceeded the design goals. This paper will outline the comparison between the original system and the predicted results of the selected design option, and the commissioning results of thermo-siphon system

20 K Helium Refrigeration System for NASA-JSC Chamber-A

A new 20 K helium refrigerator installed at NASA Johnson Space Center's Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope. The chamber previously and currently still has helium cryopumping panels (CPP) and LN2 shrouds used to create Low Earth Orbit environments. Now with the new refrigerator and new helium shrouds (45 x 65 ) the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Labs, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate a inverse coefficient of performance better than 70 W/W for a 18 KW load at 20 K (accounting for liquid nitrogen precooling power) that remains essentially constant down to 1/3 of this load. Even at 10 percent of the maximum capacity, the performance is better than 140 W/W at 20K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10kW at 15 K to 100 kW at 100K. The refrigerator is capable of operating at any load temperature from 15K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results

Commissioning of a 20 K Helium Refrigeration System for NASA-JSC Chamber A

A new 20 K helium refrigerator installed at NASA Johnson Space Center s Space Environment Simulation Laboratory (SESL) was successfully commissioned and tested in 2012. The refrigerator is used to create a deep space environment within SESL s Chamber A to perform ground testing of the James Webb Space Telescope (JWST). The chamber previously and currently still has helium cryo-pumping panels (CPP) and liquid nitrogen shrouds used to create low earth orbit environments. Now with the new refrigerator and new helium shrouds the chamber can create a deep space environment. The process design, system analysis, specification development, and commissioning oversight were performed by the cryogenics department at Jefferson Lab, while the contracts and system installation was performed by the ESC group at JSC. Commissioning data indicate an inverse coefficient of performance better than 70 W/W for a 18 kW load at 20 K (accounting for liquid nitrogen pre-cooling power) that remains essentially constant down to one third of this load. Even at 10 percent of the maximum capacity, the performance is better than 150 W/W at 20 K. The refrigerator exceeded all design goals and demonstrated the ability to support a wide load range from 10 kW at 15 K to 100 kW at 100 K. The refrigerator is capable of operating at any load temperature from 15 K to ambient with tight temperature stability. The new shroud (36 tons of aluminum) can be cooled from room temperature to 20 K in 24 hours. This paper will outline the process design and commissioning results

Analisa Resiko Postur Kerja Berdasarkan Hasil Evaluasi Menggunakan Metode Quick Exposure Check

UMKM XYZ merupakan industri bergerak dibidang pembuatan sepatu, produk yang menjadi unggulan adalah jenis sepatu bordir. Proses pengerjaan pembuatan sepatu bordir membutuhkan penanganan secara manual oleh pekerja sehingga pada proses produksinya masih terdapat serangkaian postur kerja yang tidak ergonomi. Metode penilaian postur kerja yang digunakan yaitu Quick Exposure Check (QEC). Metode QEC dipilih karena metode ini merupakan metode yang sederhana dan mudah untuk dipahami serta metode ini juga menilai dari dua sudut pandang, yaitu worker assessment dan observer assessment. Berdasarkan dari penelitian ini perhitungan kembali total exposure level dari usulan perbaikan fasilitas kerja, diharapkan mendapat nilai exposure level dengan rang

Baseline Configuration of the Cryogenic System for the International Linear Collider

The paper discusses the main constraints and boundary conditions and describes the baseline configuration of the International Linear Collider (ILC) cryogenic system. The cryogenic layout, architecture and the cooling principle are presented. The paper addresses a plan for study and development required to demonstrate and improve the performance, to reduce cost and to attain the desired reliability

PENERAPAN METODE PEMBELAJARAN DRILL DAN METODE PEMBELAJARAN KONVENSIONAL TERHADAP HASIL BELAJAR PRAKTIK TARI : EKSPERIMEN PADA PESERTA DIDIK KELAS XI SMK 1 DEPOK, SLEMAN

Penelitian ini bertujuan menguji perbedaan efektivitas pembelajaran praktik tari dengan metode drill dan metode konvensional ditinjau dari hasil belajar praktik tari. Penelitian ini merupakan bentuk eksperimen dengan rancangan nonequivalent control group design, yaitu menggunakan dua kelas sebagai kelas eksperimen dan kelas kontrol yang dipilih secara acak. Penelitian ini terdiri atas satu variabel bebas, yaitu metode drill dan metode konvensional serta satu variabel terikat, yaitu hasil belajar praktik tari. Populasi penelitian adalah seluruh peserta didik kelas XI SMK N 1 Depok tahun pelajaran 2013/2014. Sampel penelitian adalah kelas XI.PM.1 dan XI.PM.2. Data diperoleh dari hasil observasi, studi dokumentasi, dan tes. Teknik analisis data meliputi: uji prasarat anilisis, uji hipotesis serta uji Scheffe. Uji prasyarat analisis terdiri dari uji normalitas data dan uji homogenitas. Uji hipotesis menggunakan One Way Anova dengan SPSS 17 dan uji Scheffe. Uji Scheffe digunakan untuk membandingkan keefektifan kedua metode terhadap hasil belajar praktik tari. Hasil penelitian menunjukkan sebagai berikut. Kedua kelas sampel penelitian bersifat homogen berdasarkan hasil perhitungan pre-test dengan taraf signifikansi hasil perhitungan lebih besar dari taraf signifikansi yaitu 0,924 > 0,05. Setelah diterapkan treatment pada kelas eksperimen yang menggunakan metode drill, terjadi perbedaan signifikan pada hasil belajar praktik tari dibandingkan dengan kelas kontrol yang menggunakan metode konvensional. Perbedaan signifikan tersebut berdasarkan perhitungan dengan One Way Anova yang menunjukkan F hasil perhitungan F’ yaitu 167,8 > 3,99. Hal tersebut membuktikan bahwa metode drill lebih efektif dari metode konvensional ditinjau dari hasil belajar praktik tari