CFD analysis of the two-phase bubbly flow characteristics in helically coiled rectangular and circular tube heat exchangers

Due to their ease of manufacture, high heat transfer efficiency and compact design, helically coiled heat exchangers are increasingly being adopted in a number of industries. The higher heat transfer efficiency over straight pipes is due to the secondary flow that develops as a result of the centrifugal force. In spite of the widespread use of helically coiled heat exchangers, and the presence of bubbly two-phase flow in a number of systems, very few studies have investigated the resultant flow characteristics. This paper will therefore present the results of CFD simulations for the two-phase bubbly flow in helically coiled heat exchangers as a function of the volumetric void fraction and the tube cross-section design. The CFD results are compared to the scarce flow visualisation experimental results available in the open literature

An Economic Model-Based Predictive Control to Manage the Users' Thermal Comfort in a Building

The goal of maintaining users' thermal comfort conditions in indoor environments may require complex regulation procedures and a proper energy management. This problem is being widely analyzed, since it has a direct effect on users' productivity. This paper presents an economic model-based predictive control (MPC) whose main strength is the use of the day-ahead price (DAP) in order to predict the energy consumption associated with the heating, ventilation and air conditioning (HVAC). In this way, the control system is able to maintain a high thermal comfort level by optimizing the use of the HVAC system and to reduce, at the same time, the energy consumption associated with it, as much as possible. Later, the performance of the proposed control system is tested through simulations with a non-linear model of a bioclimatic building room. Several simulation scenarios are considered as a test-bed. From the obtained results, it is possible to conclude that the control system has a good behavior in several situations, i.e., it can reach the users' thermal comfort for the analyzed situations, whereas the HVAC use is adjusted through the DAP; therefore, the energy savings associated with the HVAC is increased.Spanish Ministry of Science and Innovation [DPI2014-56364-C2-1-R]; EU-ERDF funds; Competitiveness and ERDF funds; Fundacion Iberdrola Espana; Portuguese Foundation for Science & Technology, through IDMEC, under LAETA [ID/EMS/50022/2013

Epizootiološko istraživanje slinavke i šapa u Sudanu: stanje nakon dva desetljeća

In order to update information on the situation regarding foot and mouth disease (FMD) in the Sudan, a serosurvey and disease survey were conducted. Recently collected data on FMD in the Sudan showed that FMD is a major constraint to animal production in the country. It presents no threat nor does it cause mild disease in sheep and goats. The disease, with obvious clinical signs, has been detected in cattle only, and is caused by serotype O and SAT 2. Seasonal occurrence of the disease in the cold, dry season has been observed and animal movement seems to play a major role in virus dissemination. A total of 1,069 sera were collected from cattle, sheep, goats, and camel, from seven states in the Sudan, for the detection of antibodies to FMDV. Application of liquid phase blocking (LPB) ELISA revealed that antibodies to four serotypes were present in ruminants; namely O, A, SAT 1 and SAT 2. No antibodies to FMDV were detected in camel sera. The results differed from early reports regarding the prevalence of serotype specifi c antibodies in different species; for instance, in cattle, the antibodies to type A (78.13%) surpassed that of type O (69.39%) and the antibodies to type SAT 2 (44%) surpassed that of type SAT 1 (20.2%). This work elucidates the current epidemiology of FMD in some parts of the Sudan.Radi pružanja informacija o sadašnjem stanju slinavke i šapa u Sudanu provedena su serološka istraživanja te je prikazana njezina pojavnost. Svježe prikupljeni podatci o pojavi slinavke i šapa u Sudanu pokazali su da ona predstavlja veliku prepreku životinjskoj proizvodnji u toj zemlji. U ovaca i koza javlja se kao blaga bolest i ne predstavlja veliku prijetnju, dok se u goveda javlja s očitim kliničkim znakovima, a uzrokovana je serotipovima O i SAT 2. Bolest se javlja sezonski u hladnoj i suhoj sezoni, a promet životinjama ima glavnu ulogu u širenju virusa. Ukupno je bilo prikupljeno 1069 uzoraka seruma goveda, ovaca, koza i deva podrijetlom iz sedam država u Sudanu radi pretrage na prisutnost protutijela za virus slinavke i šapa. Blokirajućim imunonenzimnim testom dokazana su protutijela za četiri serotipa virusa: O, A, SAT 1 i SAT 2. Protutijela za virus slinavke i šapa nisu bila dokazana u uzorcima seruma deva. Rezultati se razlikuju od ranijih izvješća s obzirom na prevalenciju specifi čnih protutijela u različitih vrsta. Npr., specifi čna protutijela za serotip A dokazana su u 78,13% goveda, za serotip O u 69,39%, serotip SAT 2 u 44% te serotip SAT 1 u 20,2% goveda. U radu je prikazano sadašnje epizootiološko stanje slinavke i šapa u nekim dijelovima Sudana

PENGARUH LINGKUNGAN FISIK DAN KELUARGA TERHADAP PRESTASI DALAM MATA PELAJARAN IPS PADA KELAS VIII DI SMP NEGERI 17 BANDA ACEH

Banda Ace

Perancangan Strategi Keberlanjutan Perusahaan Menggunakan Kerangka Analitik Corporate Social Responsibility – Responsible Med (Studi Kasus PT Dutabahari Menara Line Dockyard)

Tesis ini merupakan usulan penyelesaian masalah pada PT Dutabahari Menara Line Dockyard (PT DMLD), Perusahaan galangan kapal di Banjarmasin yang sedang berkembang dan bersiap menghadapi persaingan global. Saat ini Perusahaan tidak memiliki rancangan strategi dan alat ukur kinerja yang baik. Dalam merancang strategi bagi keberlanjutan Perusahaan digunakan kerangka analitik dan perancangan strategi CSR Assessment Tool (CAT), Responsible-Med. CAT Responsible-Med (CAT-RM) membantu memetakan permasalahan, menganalisis, dan merancang strategi berdasarkan aspek utama keberlanjutan ISO 26000 Social Responsibility. Sumber data primer diperoleh dari survei sembilan narasumber yang memiliki kompetensi dalam menjawab dan memberikan gambaran lengkap kondisi Perusahaan. Pemetaan permasalahan memberikan angka kinerja di lima aspek, yakni: (a) workplace 72,5%, (b) marketplace 50%, (c) community 52,5%, dan (d) environment 62,5%. CAT-RM menggunakan indikator daya saing (competitiveness) dan biaya (cost) dalam memberikan penilaian pada setiap pilihan aksi. Selanjutnya indikator tersebut akan dibandingkan untuk mendapatkan nilai prioritas dalam menetapkan strategi Perusahaan. Tahapan terakhir CAT-RM adalah melakukan evaluasi dengan membandingkan kondisi periode 1 tahun sebelum dan sesudah pelaksanaan aksi yang direkomendasikan. Hasil berupa lima strategi keberlanjutan PT DMLD yang direkomendasikan oleh CAT-RM, yaitu: (i) melaksanakan konsep proses produksi, pasokan material, dan bisnis yang adil dan beretika, (ii) menyelenggarakan kegiatan pelatihan dan pendidikan untuk pekerja; (iii) melaksanakan kebijakan kesejahteraan untuk pekerja; (iv) pemilihan kontraktor dan supplier dengan pedoman komitmen terhadap lingkungan, kesehatan dan keselamatan kerja, dan etika bisnis; dan (v) jaminan kesehatan dan keselamatan di area kerja PT DMLD

HAZE AND CONVERGENCE MODELS: EXPERIMENTAL COMPARISON

International audienceBad environmental conditions like bad weather, such as fog and haze, and smoke-filled monitored closed areas, cause a degradation and a loss in contrast and color information in images. Unlike outdoor scenes imaged in a foggy day, an indoor artificial hazy scene can be acquired in controlled conditions, while the clear image is always available when the smoke is dispersed. This can help to investigate models of haze and evaluate dehazing algorithms. Thus, an artificial indoor scene was set up in a closed area with a mean to control the amount of haze within this scene. While a convergence model simulates correctly a small amount of haze, it fails to reproduce the same perceived hazy colors of the real image when haze density is high. This difference becomes obvious when the same dehazing method is applied to both images. Unlike simulated images, colors in real hazy images are resulted from environmental illuminants interference

A Color Image Database for Haze Model and Dehazing Methods Evaluation

International audienceOne of the major issues related to dehazing methods (single or multiple image based) evaluation is the absence of the haze-free image (ground-truth). This is also a problem when it concerns the validation of Koschmieder model or its subsequent dehazing methods. To overcome this problem, we created a database called CHIC (Color Hazy Image for Comparison), consisting of two scenes in controlled environment. In addition to the haze-free image, we provide 9 images of different fog densities. Moreover, for each scene, we provide a number of parameters such as local scene depth, distance from the camera of known objects such as Macbeth Color Checkers, their radiance, and the haze level through transmittance. All of these features allow the possibility to evaluate and compare between dehazing methods by using full-reference image quality metrics regarding the haze-free image, and also to evaluate the accuracy of the Koschmieder hazy image formation model

Does Dehazing Model Preserve Color Information?

International audience—Image dehazing aims at estimating the image information lost caused by the presence of fog, haze and smoke in the scene during acquisition. Degradation causes a loss in contrast and color information, thus enhancement becomes an inevitable task in imaging applications and consumer photography. Color information has been mostly evaluated perceptually along with quality, but no work addresses specifically this aspect. We demonstrate how dehazing model affects color information on simulated and real images. We use a convergence model from perception of transparency to simulate haze on images. We evaluate color loss in terms of angle of hue in IPT color space, saturation in CIE LUV color space and perceived color difference in CIE LAB color space. Results indicate that saturation is critically changed and hue is changed for achromatic colors and blue/yellow colors, where usual image processing space are not showing constant hue lines. we suggest that a correction model based on color transparency perception could help to retrieve color information as an additive layer on dehazing algorithms

Pemanfaatan Kulit Manggis dan Rumput Laut dalam Pembuatan Permen Jelly

The aims of this study to get the best ratio of mangosteen peel and seaweed to produce jelly candies with good quality. This study was held experimentally using CRD (Complete Randomized Design) of five treatments and three replications. The treatment were JKR1 (ratio mangosteen peel and seaweed 2 : 1), JKR2 (ratio mangosteen peel and seaweed 3 : 2), JKR3 (ratio mangosteen peel and seaweed 1 : 1), JKR4 (ratio mangosteen peel and seaweed 2 : 3) and JKR5 (ratio mangosteen peel and seaweed 1 : 2). Data were analized by ANOVA and DNMRT at the level of 5%. The result showed that there was significant influence (P0,05) in moisture content. The ratio of mangosteen peel and seaweed in the treatment JKR3 (mangosteen peel and seaweed ratio 1:1) was best treated with a moisture content 26.51%, ash content 0.75%, crude fiber content 2.22%, reducing sugar content 9.45%, antioxidant content 21.06 µg/ml. The result of sensory analysis of JKR3 were a little bit reddish purple colour, very sweetness taste, the texture was springy and overall assesment of jelly candy was preferred by the panelists