Rewetting processes during PWR reflood

Rewetting of heated surfaces is important in many physical processes and has important technological applications. Understanding of this phenomenon is required in many engineering and scientific fields. It is one of the most crucial phenomena to be considered for the safety analysis of the design basis Loss‐of‐Coolant Accident (LOCA) in light water reactors (Pressurized Water and Boiling Water Reactors). To mitigate the consequences of LOCA, water is fed into the reactor core via an emergency core cooling system; in the PWR, this water is fed to the core via the lower plenum (“bottom reflooding”) and in the BWR, this water is sprayed onto the top of the core (“top reflooding”). In both the cases, a quench front is formed which moves rather slowly. Ahead of quench front, complex and chaotic processes are occurring over a very small axial region where high temperature gradient exists. The heat transfer mechanism is not well known in this region. In this work, the detailed physics of the rewetting processes has been investigated both theoretically and experimentally. The thermal hydraulic behaviour of hot vertical channels during emergency core cooling conditions would be expected to be flow direction‐dependent, it was important to consider the two cases (top reflooding and bottom reflooding) separately. It was possible for the first time, to the author’s knowledge, to apply the fast response infra‐red thermal imaging system to study the rewetting process during top and bottom reflooding of heated vertical surfaces. The important contribution of this work was the use of this new technology to sense the variation of temperature with time at multiple nearby locations at the quench front. In the top reflood experiments, a heated stainless steel pate was quenched by a falling film flow. Through an infrared‐transparent substrate embedded in the plate and coated with platinum, temperature measurements at a location near the rewetting front were achieved using infrared thermal imaging system. The temperature/time traces showed fluctuations in temperature indicating occurrence of intermittent contacts at the quench front. A high speed video camera was also employed to capture rewetting processes by the visual observation of the rewetting front from the top surface. In the visual observations, the liquid film has been seen making intermittent contacts with the hot surface. In these experiments, the effect of the flow rate and the degree of sub‐cooling of the feed liquid has been studied. The rewetting temperature and the characteristic length of the intermittent contact region have been deduced from the experimental results. Experiments were also done to measure temperature changes at the rewetting front for the case of bottom reflooding of a heated tube using a similar technique to that employed for the studies of top reflooding. The results suggested that the rewetting behaviour was different depending on whether the reflood rate was high or low. For high reflood rate, the observations are consistent with the regime above the rewetting front being of the inverted annular type and, for lower reflooding rates, the results are consistent with the rewetting front corresponding to a film dryout in annular flow. An important finding from these experiments is the identification of transient temperature fluctuations in the transition region for the high flooding rate case. These are similar to those observed in the top reflood case and it seems very likely that these fluctuations are associated with intermittent wetting of the surface in this region. An attempt has been made to model rewetting phenomena in which the mechanism of heat transfer at the quench has been proposed. The postulated mechanism is transient near‐surface cooling resulting from intermittent solid‐liquid contacts, followed by recovery of the surface temperature of the metal substrate, with explosive vaporization occurring when the homogeneous nucleation temperature is restored at the metal‐water interface. A one‐dimensional rewetting model was constructed to explain the cyclical process; this model predicted the cyclical behaviour, with the expected qualitative dependence on system parameters. Its predictions are quantitatively consistent with experimental observation, in that the unsteady model analysis brackets the experimentally observed periodicity of the quasi‐steady actual process. The one‐dimensional model of the process has been complemented by twodimensional simulations using a commercial finite element code (ANSYS). In these simulations, an intermittent contact region has been modelled by imposing a heat transfer coefficient over a certain length between dry and wet regions. A parametric study was performed to see the effect of the rewetting velocity, the wet side heat transfer coefficient, intermittent contact heat transfer coefficient, and the length of intermittent contact region

Upaya meningkatkan prestasi belajar shalat melalui metode demonstrasi pada siswa kelas II di MI Nurul Huda Raji Demak tahun 2011

Tujuan yang menjadi kajian peneliti, yaitu: 1) Untuk menggambarkan proses pembelajaran shalat engan menggunakan Metode Demonstrasi di Kelas II MI Nurul Huda Raji Tahun 2011.2) Untuk mengetahui ada atau tidak adanya pembelajaran Shalat dengan Metode Demonstrasi di Kelas II MI Nurul Huda Raji Tahun 2011 dalam peningkatan prestasi siswa. . Penelitian ini adalah Penelitian Tindakan Kelas (Classroom Action Research) yang dilakukan melalui 2 siklus dengan setiap siklus tahapannya adalah perencanaan, tindakan, observasi dan refleksi. Data penelitian diperoleh melalui Model dokumentasi, Model observasi dan Model tes. Indikator kinerja penelitian berupa tercapainya ketuntasan belajar secara indiviual dan klasikal. Hasil penelitian menunjukkan : 1) Yang dilakukan oleh guru dalam pelaksanaan Metode Demonstrasi pada mata pelajaran PAI materi Shalat kelas II MI Nurul Huda Raji, yaitu guru harus mempersiapkan RPP dan perangkat pembelajaran dengan baik. Guru harus lebih meningkatkan motivasi peserta didik. Guru harus lebih dapat menjelaskan alur pembelajaran dengan menggunakan Model demontrasi. Guru harus mendemonstrasikan shalat secara pelan-pelan, guru menyuruh peserta didik untuk mengamati segala kegiatan demonstrasi yang dilakukan oleh guru dan teman yang sudah bisa. Guru harus sering berkeliling mendekati peserta didik dan mencatat kegiatan yang terjadi di dalam kelas selama kegiatan demonstrasi berlangsung. Guru mengisi Lembar Observasi Siswa, 2) Hasil belajar peserta didik sebelum Metode Demonstrasi pada mata pelajaran PAI materi Shalat kelas II MI Nurul Huda Raji belum memenuhi standar KKM (kriteria ketuntasan minimal), namun setelah diterapkan Metode Demonstrasi pada mata pelajaran PAI materi Shalat kelas II MI Nurul Huda Raji, hasil belajar peserta didik mengalami peningkatan. Terjadinya peningkatan karena tindakan kelas yang dilakukan oleh guru pada Metode Demonstrasi pada mata pelajaran PAI materi Shalat kelas II MI Nurul Huda Raji. Terlihat bahwa pada siklus kedua telah mengalami peningkatan yaitu telah mencapai tingkat sempurna, pada siklus I yaitu mencapai 60 % atau sebanyak 23 peserta didik yang tuntas belajar dan meningkat pada siklus II ada 88,5% atau 33 peserta didik yang tuntas belajarnya. Ini artinya metode demontrasi yang digunakan dalam pembelajaran materi shalat efektif untuk meningkatkan hasil belajar peserta didik.. Berdasarkan hasil penelitian ini diharapkan akan menjadi bahan informasi dan masukan bagi para mahasiswa, para tenaga pengajar, para peneliti dan semua pihak yang membutuhkan di lingkungan IAIN Walisongo Semarang

THE THRESHOLD VALUE OF ENAMEL MINERAL SOLUBILITY AND DENTAL EROSION AFTER CONSUMING ACIDIC SOFT DRINKS

It is known that the threshold value of enamel mineralsolubility (K, Na, Fe, Mg, Cl, P, Ca, F, C) has significant difference (p < 0.05) after being exposed to folic acid. Meanwhile, Fe did not\ud have significant difference (p = 0.090) after being exposed to citric acid. Similarly, C did not have significant difference (p = 0.063)after being exposed to bicarbonate acid. Furthermore, it is also known that the threshold time value of dental erosion are on the 105th\ud day for folic acid, on the 111th day for citric acid, and on the 117th day for bicarbonate acidDental erosion is irreversible and caused by acidic softdrink consumption. Dental erosion prevention already been done, but it still has not been satisfying since the consumption of acidic softdrink is still high. There is still not any dates that explainthe threshold value of enamel mineral solubility and the occurance of dental erosion after consuming acidic softdrink. Purpose: This research aims to find the threshold value of enamel mineral solubility and dental erosion before and after consuming acidic soft drinks.Methods: Subjects of the research are saliva and enamel of 12 marmooths, which have some criteria such as age ???70 days, body weight???600 grams, and teeth considered to be healthy. The sample devided equally into 4 groups. Each of those marmooths was given adrink as much as 2.5 cc/consumption (there are 1, 2 and 3?? per day) by using syringe without injection needle. Salivary minerals thenwere examined by using Atomic Absorption Spectrophotometric (ASS), while dental erosion was examined using Scanning ElectronMicroscop (SEM). The data were analyzed by using Paired t-test. Results: It is known that the threshold value of enamel mineralsolubility (K, Na, Fe, Mg, Cl, P, Ca, F, C) has significant difference (p < 0.05) after being exposed to folic acid. Meanwhile, Fe did not\ud have significant difference (p = 0.090) after being exposed to citric acid. Similarly, C did not have significant difference (p = 0.063)after being exposed to bicarbonate acid. Furthermore, it is also known that the threshold time value of dental erosion are on the 105th\ud day for folic acid, on the 111th day for citric acid, and on the 117th day for bicarbonate acid. Conclusion: Threshold value of enamelmineral solubility before and after consuming soft drinks containing acid is different. Based on the threshold value of dental erosion,it is known that folic acid is the most erosive acid

PENGARUH BIAYA MODAL (COST OF CAPITAL) TERHADAP PROFITABILITAS PADA BANK UMUM SWASTA NASIONAL DEVISA YANG TERDAFTAR DI BURSA EFEK INDONESIA TAHUN 2011-2014

Penelitian ini bertujuan untuk mengetahui pengaruh biaya modal (Cost of capital) terhadap profitabilitas pada bank umum swasta nasional devisa yang terdaftar di bursa efek, dimana biaya modal diproksikan oleh Weighted Average Cost Of Capital (WACC) dan profitabilitas diproksikan oleh Return On Assets (ROA). Objek penelitian ini adalah Bank Umum Sawasta Nasional Devisa Yang Terdaftar Di Bursa Efek. Metode penelitian yang digunakan adalah metode deskriptif verifikatif. Teknik pengumpulan data yang digunakan adalah metode dokumentasi. Dokumen tersebut meliputi laporan keuangan dan laporan tahunan Bank Umum Swasta Nasional Yang Terftar Di Bursa Efek. Teknik pengolahan data dalam penilitian ini menggunakan perhitungan statistik Korelasi Pearson Product Moment, setelah itu melakukan perhitungan Koefisien determinasi dan uji t dengan tingkat signifikansi 5%. Berdasarkan hasil pengujian statistik diperoleh hasil bahwa biaya modal berpengaruh negatif terhadap profitabilitas sebesar 3.96%, artinya jika biaya modal naik maka profitabilitas akan menurun, begitupun sebaliknya. Sedangakan yakni sebesar 96.04% dipengaruhi oleh faktor-faktor lain yang tidak dibahas dalam penelitian ini. Implikasi dari hasil penelitian ini adalah bank harus mengelola asetnya secara baik dan menemukan komposisi pendanaan yang dapat meminimlakan biaya modal, sehingga profitabilitas yang optimal akan tercapai. Kata kunci : Biaya Modal, Profitabilitas THE EFFECT OF COST OF CAPITAL TO PROFITABILITY IN THE NATIONAL PRIVATE COMMERCIAL BANK FOREIGN EXCHANGE LISTED ON THE STOCK EXCHANGE IN 2011-2014 Muhammad Ilyas, Tutor: Drs. H. Umar Faruk, M.Si ABSTRACT This research aims to determine the effect of the cost of capital (cost of capital) to profitability in the national private commercial bank foreign exchange-listed on the stock exchange, where the cost of capital is proxied by the Weighted Average Cost Of Capital (WACC) and profitability is proxied by Return On Assets (ROA) , The object of this research is the National Private Commercial Bank Foreign Exchange Listed on the Stock Exchange. The method used is descriptive method verification. Data collection techniques used is a method of documentation. These documents include financial statements and annual report of the National Private Banks The Terftar On the Stock Exchange. Data processing techniques in this research using statistical calculations Pearson Product Moment Correlation, then perform the calculation coefficient of determination and t test with significance level of 5%. Based on the results of statistical tests showed that the cost of capital negatively affect the profitability of 3.96%, meaning that if the cost of capital rises, the profitability will decrease, and vice versa. Sedangakan which is equal to 96.04% influenced by other factors not addressed in this study. The implication of this research is the banks should manage their assets well and finding funding composition can meminimlakan cost of capital, so that the optimal profitability will be achieved

Experimental Analysis of Ultra Wideband In Vivo Radio Channel

In this paper, we present the experimental analysis of in vivo wireless channel response on Ultra-Wideband (UWB) with the frequencies between 3.1-10.6 GHz. The analysis proves the location dependent based characteristics of in vivo channel. The results clearly show the highly multipath scenario. It can also be observed that the multipath effect of the channel is much higher in the denser areas, i.e. an antenna placed within the intestine area or inside the stomach. Results prove that in vivo channel is different from a conventional communication channel and therefore extensive studies need to be done to understand the channel

The Influence of CLL on EFL Learners’ Speaking Skill

Some students in the university got some difficulties to express their ideas, especially expressing in foreign language such as English. How to start comunication and interaction sometime need someone to stimulate. The phenomenon often encountered in various levels of education even to the students college. The students tended to be very subjective towards topics, their peer or even partner. In the teaching and learning process, the teacher not only transfer the information to the students but also facilitate the students, stimulate to learn English and provide the technique suitable with the students’ need. Teaching English language might be carried out through several techniques, one of them was CLL (Community Language Learning). In this technique, students were treated as clients who could express their problems to the counselor as well as in the community. In addition, the teacher played the role of translator to help students express themselves using English. This means that learners had enough opportunities to speak without worrying about their limitations in using English. The results showed that CLL helped students to express ideas systematically. The ideas were organized well, understandable, and standardized. In addition, CLL improved the result of students’ score in speaking skill. The mean score increased from 54.74 in pre-test to 72.86 in post-test. It means that CLL gave good influence on students’ speaking skill

Feature-Based Comparison of Language Transformation Tools

Code transformation is the best option while switching from farmer to next technology. Our paper presents a comparative analysis of code transformation tools based on 18 different factors. These factors are Classes, pointers, Access Specifiers, Functions and Exceptions, etc. For this purpose, we have selected varyCode, Telerik, Multi-online converter, and InstantVB. Source Language considered for this purpose is C sharp (C#) and the target language is Visual Basics (VB). Results show that VaryCode is best among the four tools as its converted programs throw fewer errors and require minor changes while running the program

Implementasi Aplikasi collabsproject.com di Masa Pandemi Covid-19

Artikel ini bertujuan untuk membahas permasalahan para pekerja di masa pandemi yang banyak di PHK/Di rumahkan dan memberi solusi untuk para pekerja lewat platform collabsproject.com. Dimasa pandemi seperti sekarang ini, para pekerja di hadapkan pada situasi sulit dimana perusahaan perusahaan banyak melakukan pemutusan hubungan kerja akibat dampak dari pandemi yang berkepanjangan dan belum bisa untuk di prediksi pandemi ini akan selesai. Dengan kebutuhan sehari hari yang tetap harus terpenuhi banyak karyawan – karyawan yang memutuskan untuk bekerja freelance di dunia digital, dengan adanya aplikasi collabsproject.com yang berbasis website maka para pencari kerja paruh waktu/freelance dapat dengan mudah mendapatkan pekerjaan yang mereka cari sesuai dengan keahlian dan kompetensi mereka masing – masing. Artikel ini ditulis dengan pendekan penelitian kualitatif.  Hasil analisis menunjukan bahawa pertumuhan ekonomi indonesia dapat diukur melalui peningkatan atau penurunan produk domestik bruto (PDB/GDP) karena indikator yang berhubungan dengan jumlah pengangguran adalah GDP.Artikel ini bertujuan untuk membahas permasalahan para pekerja di masa pandemi yang banyak di PHK/Di rumahkan dan memberi solusi untuk para pekerja lewat platform collabsproject.com. Dimasa pandemi seperti sekarang ini, para pekerja di hadapkan pada situasi sulit dimana perusahaan perusahaan banyak melakukan pemutusan hubungan kerja akibat dampak dari pandemi yang berkepanjangan dan belum bisa untuk di prediksi pandemi ini akan selesai. Dengan kebutuhan sehari hari yang tetap harus terpenuhi banyak karyawan – karyawan yang memutuskan untuk bekerja freelance di dunia digital, dengan adanya aplikasi collabsproject.com yang berbasis website maka para pencari kerja paruh waktu/freelance dapat dengan mudah mendapatkan pekerjaan yang mereka cari sesuai dengan keahlian dan kompetensi mereka masing – masing. Artikel ini ditulis dengan pendekan penelitian kualitatif.&nbsp; Hasil analisis menunjukan bahawa pertumuhan ekonomi indonesia dapat diukur melalui peningkatan atau penurunan produk domestik bruto (PDB/GDP) karena indikator yang berhubungan dengan jumlah pengangguran adalah GDP

Impact of various insecticides and planting dates on the management of maize stem borer Chilo partellus

Field experiment on the impact of various insecticides and planting dates on the management of maize stem borer Chilo partellus in maize crop was conducted at Malakandair farm of The Agricultural University, Peshawar. Maize variety Jalal was raised on three different dates viz. 22nd June, 04 July and 16th July, 2014; and treated with Furadon 3G, Thimet 5G, Ripcord 10EC, Thiodan 35 EC, Karate 25 EC. Results revealed that means for number of healthy plants m-2, infested plants m-2, larvae in stubbles m-2, dead hearts m-2, and grains yield kg ha-1 showed significant effects due to insecticides and sowing dates. The number of healthy plants m-2 and yield in kg ha-1 were highest while the number of infested plants m-2, dead hearts m-2 and larvae in stubbles m-2 were lowest in the plots treated with Furadon 3G (77.46, 1759.44, 11.63, 9.42 and 3.56) followed by Thimet (75.16, 1643.22, 14.64, 10.34 and 5.00) as compared to other extremes in Control (61.91, 1131.78, 21.48, 17.29 and 10.56). The number of healthy plants m-2 and yield in kg ha-1 were highest while the number of infested plants m -2, dead hearts m-2 and larvae in stubbles m-2 were lowest in the plots sown on 22nd June (74.09, 1596.44, 15.20, 10.88 and 5.28) as compared to other extremes in plots sown on 16th July (71.24, 1401.50, 17.13, 13.73 and 7.44 respectively). The sowing date of 22nd June along with the application of Furadon 3G showed significant results for all the recorded parameters as compared to other treatments. Keywords: Insecticides, Planting dates and Maize Stem Bore