AN EVALUATION OF CONSTITUENT CORRELATIONS FOR PREDICTING REFRIGERANT CHARACTERISTICS IN ADIABATIC CAPILLARY TUBES

DEBASISH SARKER,LYUN-SU KIM,KI-DONG SON,정지환,장근선 대한설비공학회 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.2

Capillary tubes are widely used as a refrigerant flow control device in small refrigeration systems. Since the flow behavior inside the capillary tube is complex, many physical models are necessary to predict the characteristics of the refrigerant flow in a capillary tube. In the present paper, refrigerant flow characteristics inside the capillary tube have been studied to find out recommended empirical correlations of influential parameters. A numerical capillary model is developed to predict the refrigerant characteristics. Various empirical correlations regarding single-phase friction factor, two-phase viscosity, two-phase frictional multiplier and metastable flow are examined using this numerical capillary model. Calculated results are compared with experimental data to examine the accuracy in terms of required capillary tube length and mass flow rate. Based on the comparison, recommended correlations are selected to be used for capillary flow analysis.

Aerodynamic modifications for reduction of wind loads on cross plan shaped tall building

Debasish Kumar,Sujit Kumar Dalui 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.2

Corner modification plays an essential role in the reduction of the wind load and responses on tall buildings. The present study investigates the effectiveness of different corner modifications (chamfered, rounded, and recessed corners) to reduce the wind load on regular cross plan shaped tall buildings using the computation fluid dynamics technique. Here, ANSYS CFX is used to simulate the boundary layer wind environment around the building and compared with experimental results. The numerically simulated data are compared with some previous wind tunnel test data on the ‘+’ plan building. Based on the numerical study, flow pattern near the corner regions, pressure contour, the variation of pressure coefficient along the periphery of the building, force and moment coefficients for three corner modified models are analyzed and compared with sharp edged cross plan shaped model to comprehend the extent of nonconformities due to corner modifications. The rounded corner modification is most effective in suppressing the wind load compared to chamfered and recessed corners. For rounded corners with 50% corner cut, the reduction in force and moment coefficients is substantial, with up to 26.26% and 28.58%, respectively, compared to sharp edged corners. A sudden shoot up in the negative Cp values near edges of the corner modified model, should require special attention in the design of cladding components. This paper led to comprehend the wind-induced responses of cross plan shaped building with various corner configurations.

Level of Service for On-street Parking

Debasish Das,Mokaddes Ali Ahmed 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.1

Parking of vehicle is one of the most important issues of the urban transportation system in any Central Business District (CBD). A sharp rise in vehicular ownership and insufficient transit system give rise to the huge on-street parking demand leading to a reduction in effective carriageway width, flow speed, creating unnecessary congestion, etc. The problems can be controlled by providing an efficient parking system. The present study aims to estimate the Level of Service (LOS) of on-street parking. LOS is calculated based on three parking selection criteria, viz. Parking Characteristic (PC), Safety Characteristic (SC) and Design Characteristic (DC). Four CBDs of Kolkata Metropolitan Area (KMA) are selected as a case study area. The overall LOS equation is formulated by Analytic Hierarchy Process (AHP). Cluster analysis and Zero dimension process are used to standardize the variables to designated LOS. Various surveys are carried out for data collection. The data are analyzed using SPSS. Finally, the overall LOS for on-street parking is estimated for all the selected CBDs.

Context Aware Communication in Ubiquitous Computing Environment

Debasish Chakraborty,Hideyuki Takahashi,Takuo Suganuma,Norio Shiratori 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7

Healthcare is increasingly becoming a distributed service involving stakeholders and resources who may be physically far from each other. But privacy and security are potential problems. Patient’s data should be available irrespective of their location, but only to authorized person. Not only that, the relationship between the person under observation and other related people, are different and the security and other characteristics concerning the data may also differ accordingly. In this paper we propose a system where an overlay network can be built in an ad hoc basis and links between different entities will be established according to the social relationship between the object person and the person at the other end and the situation of the observed person. Unlike traditional 24-hrs monitoring system, we argued that an ondemand, requirement oriented system will be beneficial for efficient resource utilization, specially in wireless communication.

Performance of heated pin fin arrangement in a rectangular cavity-An experimental approach

Debasish Das,Ankur Dwivedi,Satya Prakash Verma 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4

For the last few decades there has been very remarkable growth in electronics and computing technologies and it is still continuing unceasingly. The performance of various engineering devices is limited by thermal management problems. The present investigation deals with heat transfer augmentation through pin fins in gamma of an air-filled rectangular cavity as function of corresponding pertinent factors- fin height, fin spacing as well as Rayleigh number and suggests a direction of future advancements. The experiments are carried out for wide domains of numerous persuading parameters- fin height (12.5 mm ≤ L ≤ 37.5 mm), fin spacing (25 mm ≤ S ≤ 100 mm) and Rayleigh number (360000 ≤ Ra ≤ 680000). Fin spacing is determined as most critical parameter affecting system performance.

The consolidation of deep tube well technology in safe drinking water provision: the case of arsenic mitigation in rural Bangladesh

Debasish Kumar Kundu,Bas J.M. van Vliet,Aarti Gupta 기술경영경제학회 2016 ASIAN JOURNAL OF TECHNOLOGY INNOVATION Vol.24 No.2

This paper explains why and how deep tube well as a safe drinking water technology hasbecome dominant in mitigating the arsenic crisis in rural Bangladesh. We do so by applyinginsights from the Multi-Level Perspective on transitions in explaining changes in the safesocio-technical drinking water regime in rural Bangladesh. Data about seven dimensions ofregime change were gathered from key actors through in-depth interviews, focus groupssessions, a survey, and a workshop. The findings reveal that with the introduction of deeptube well as an arsenic mitigation technology, the observed changes in the seven dimensionshelp to transform the existing safe drinking water regime in order to re-stabilise it. Technological attributes, symbolic meaning, industry structures, and techno-scientificknowledge have supported an evolving dominance of the deep tube well. Besides, userpractices as well as related infrastructures have adapted to the use of deep tube wells, andnew policies stimulated its application. We argue that the dimensions of the technologychange in the existing regime are consistent with the features of incremental innovation. Byoffering such insights, we show the relevance of the Multi-Level Perspective on transitionsto analyse socio-technical innovation in a developing world context.

Ceramic - Polymer Nanocomposite: Alternate Choice of Bone

Debasish Sarkar,Min Cheol Chu,Seong Jai Cho 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.6

This study evaluates a range of materials that may be used to design prostheses for bone. It is found that nanocrystallineceramic-polymer composite could be the best material for prosthetic bone with respect to biocompatibility, morphology, chemis-try, and compatibility with the piezoelectric and mechanical behavior of long human bones, such as the femur.

Optimizing the Management of High-Risk, Localized Prostate Cancer

Debasish Sundi,Byong Chang Jeong,이승배,Misop Han 대한비뇨의학회 2012 Investigative and Clinical Urology Vol.53 No.12

Prostate cancer has a high prevalence and a rising incidence in many parts of the world. Although many screen-detected prostate cancers may be indolent, prostate cancer remains a major contributor to mortality in men. Therefore, the appropriate diagnosis and treatment of localized prostate cancer with lethal potential are of great importance. High-risk, localized prostate cancer has multiple definitions. Treatment options that should be individualized to each patient include observation, radical prostatectomy,external beam radiotherapy, brachytherapy, androgen deprivation, and combined modality treatment. Specific outcomes of radical prostatectomy and combined modality treatment for high-risk prostate cancer are reviewed. The rationale for extended pelvic lymphadenectomy at the time of surgery is discussed, as is the role for surgery in the setting of node-positive, high-risk disease. There is not yet a biomarker that accurately identifies lethal prostate cancer, but rigorous clinical studies have identified methods of optimizing oncologic outcomes in high-risk men. Prostate cancer has a high prevalence and a rising incidence in many parts of the world. Although many screen-detected prostate cancers may be indolent, prostate cancer remains a major contributor to mortality in men. Therefore, the appropriate diagnosis and treatment of localized prostate cancer with lethal potential are of great importance. High-risk, localized prostate cancer has multiple definitions. Treatment options that should be individualized to each patient include observation, radical prostatectomy,external beam radiotherapy, brachytherapy, androgen deprivation, and combined modality treatment. Specific outcomes of radical prostatectomy and combined modality treatment for high-risk prostate cancer are reviewed. The rationale for extended pelvic lymphadenectomy at the time of surgery is discussed, as is the role for surgery in the setting of node-positive, high-risk disease. There is not yet a biomarker that accurately identifies lethal prostate cancer, but rigorous clinical studies have identified methods of optimizing oncologic outcomes in high-risk men.

Reactive Behavior of Ferrihydrite and Aluminic Ferrihydrite Toward the Adsorption of Arsenate

Debasish Mohapatra,박경호,Debaraj Mishra,G. Roy Chaudhury,R. P. Das 한국자원공학회 2006 Geosystem engineering Vol.9 No.2

The adsorption of arsenate (As(V)) on “ferrihy- drite” prepared by two different methods; “aluminic ferrihydrite” (Fe(III)/Al(III) molar ratio 1:1) and the stability of As(V) bearing materials were investigated. The parameters optimized for adsorption were pH, contact time, adsorbent and As(V) concentration. For leaching study four different leaching reagents (10 mg C/L dissolved organic matter, 0.1M phosphate, 0.1M citrate and 0.1M oxalate) were used. The kinetics of arsenic adsorption on both type of ferrihydrites were similar with an equilibrium time of 1h; whereas, in case of aluminic ferrihydrite the equilibrium time was 3h. For aluminic ferrihydrite, maximum adsorption was found at pH 6.0. Whereas, for ferrihydrites pH 7.0 was found to be the best for As(V) adsorption. The highest As(V) adsorption capacity was shown by aluminic ferrihydrite (21.8 mg/g), followed by ferrihydrite prepared by emulsion method and ferrihydrite prepared by ordinary method (14.9 and 9.8 mg/g, respectively). In case of As(V) extraction from the loaded materials, the pH had a significant effect. In all cases, except citrate for aluminic ferrihydrite, extraction decreased with increasing pH in the range 5.0- 8.0. For oxalate the iron extraction and for citrate the aluminium extraction followed the same trend as that for arsenic as a function of pH, suggesting that dissolution of these metals and consequent release of the adsorbed arsenic is one of the main mechanisms for arsenic extraction. However, for phosphate and DOM, the As(V) extraction mechanism was competition between arsenic and those anions for adsorption sites.

GLOBAL FINANCIAL CRISIS AND FOREIGN DEVELOPMENT ASSISTANCE SHOCKS IN LEAST DEVELOPING COUNTRIES

DEBASISH KUMAR DAS,CHAMPA BATI DUTTA 중앙대학교 경제연구소 2013 Journal of Economic Development Vol.38 No.2

This paper evaluates whether the exogenous component of the global financial crisis affects OECD-DAC EU donor countries ODA disbursements to the LDCs and how it impacts on LDCs economic prosperity. Using both static and dynamic panel techniques, we find that global financial crisis in OECD-EU donor countries are causes for the significant downside of ODA flows to the LDCs. Consequently it adversely affects through the various transmission channels (e.g., ODA disbursements, remittances, bilateral financial flows, export growth) to the LDCs economic growth. Our results also explore that due to countercyclical role of ODA flows from the donors’ largely affect to the LDCs economic development process negatively. The robustness checks using alternative estimation technique supports our original estimation results in every context.