Optimization of furfural production from millet husk using response surface methodology

Biomass has been recognized as a viable source for energy and bio-based chemicals. This study reported furfural production from millet husk via simultaneous hydrolysis and dehydration processes. Effect of reaction variables such as temperature (120–200°C), resident time (15–45 min), and acid concentration (5–10%) was studied using central composite design. Furfural yield (71.55%) was achieved at 184°C, 39 min, and 9% acid concentration. FT-IR spectrum of the produced furfural showed absorption at 1,697 and 2,880 cm^?1 indicating a conjugated carbonyl functional group and aldehydic hydrogen. The results revealed that millet husk could be a potential substrate for furfural production.     

Utilizing Accessible Heat Enhancing Cooling Effect with Three Bed Solar Adsorption Chiller

ABSTRACT

Conventional solar heat-driven single stage two bed chillers demand a large area for installation of solar thermal collector to activate the chiller, but in a highly populated tropical country open spaces is insufficient. In the intention to utilize accessible solar energy with better performance, a mathematical investigation is carried out with a three bed adsorption cooling unit working with silica gel-water pair. The studied chiller is powered by direct solar heat collected by a series of compound parabolic concentrator solar thermal collectors without any heat or mass recovery. The working principal of the chiller is, in principle, the same as the conventional two-bed adsorption chiller. However, instead of two half cycles, there are three one third cycles in the proposed chiller in which at every cycle the former desorber is kept in the precooling mode and as an adsorber for the next two one third cycles, respectively. As desorption kinetic is faster than the adsorption kinetics, this longer precooling mode helps the silica gel granules to adsorb more water molecules and increase evaporation rate. Hence, a better cooling effect of at least 1°C can be observed, increases chiller working hour after sunset for almost a further one hour.     

Defects creation in sapphire by swift heavy ions: A fluence depending process

Single crystals of sapphire (α-Al₂O₃) were irradiated at GANIL with 0.7 MeV/amu xenon ions corresponding to an electronic stopping power of 21 keV/nm. Several fluences were applied between 5 × 10¹¹ and 2 × 10¹⁴ ions/cm². Irradiated samples were characterized using optical absorption spectroscopy. This technique exhibited the characteristic bands associated with F and F⁺ centers defects. The F centers density was found to increase with the fluence following two different kinetics: a rapid increase for fluences less than 10¹³ ions/cm² and then, a slow increase for higher fluences. For fluences less than 10¹³ ions/cm², results are in good agreement with those obtained by Canut et al. [B. Canut, A. Benyagoub, G. Marest, A. Meftah, N. Moncoffre, S.M.M. Ramos, F. Studer, P. Thévenard, M. Toulemonde, Phys. Rev. B 51 (1995) 12194]. In the fluences range: 10¹³-10¹⁴ ions/cm², the F centers defects creation process is found to be different from the one evidenced for fluences less than 10¹³ ions/cm².     

Technical appraisal of solar home systems in Bangladesh: A field investigation

Solar Home System (SHS) based rural electrification has experienced a considerable growth in Bangladesh since the start of the Rural Electrification and Renewable Energy Development Project (REREDP) in 2003. The initial target of 50,000 SHS installations in off-grid areas was achieved within 2.5 years, 3 years ahead of schedule. After achieving a revised target of 200,000 SHSs, ahead of schedule in early 2009, a new target of 1 million SHS installations by 2012 was set. The installation of about 0.5 million systems by March 2010 indicates that the current target may well be achieved before the deadline. The size of the SHS market and its impact on the regeneration of the rural economy make it necessary to investigate the quality and reliability of the installed SHSs, if the continued success of the initiative is to be maintained. This paper reports on the findings from a field-based technical appraisal of SHS installations in Bangladesh. Sixty geographically dispersed installation sites were visited. Physical characteristics of the SHSs and their system components were tested to ascertain compliance with and deviations from the approved specifications. Despite the overwhelming success of the REREDP project, the study revealed various shortcomings. Notable among these are: incompatible and sub-optimal component configurations, faulty installations and a lack of effective quality assurance mechanism. The findings are contextualized and the ways to address the identified shortcomings are discussed.     

Correction to: Contamination of TiO2 thin films spin coated on borosilicate and rutile substrates

Journal of Materials Science -     

Novel Cost Efficient Resource Allocation Technique Based on Deadline and Budget Constraints for Edge Users

Wireless Personal Communications - The edge computing paradigm has experienced quick development in recent years. This paradigm is featured by pushing the storage and computational resources closer...     

采用振动台进行3维单层板系统的动力分析

在几组地面运动作用下,采用振动台对预制的3维夹芯板单层建筑进行足尺动态试验。研究的目的是获取所描述系统在动态荷载下的抗震性能,例如,线性和非线性结构特征、可塑性、刚度退化、破坏机制。通过分析,得出固有频率、振动模式及试验与数值分析结果的对比。此外,对横向变形采用试验方法进行测量并与数值计算结果比较;安装加速计测量两个正交方向的加速度。结果显示,对于强地震,3维夹芯板系统具有相当大的抵抗作用。其抵抗强地震的主要原因为：1）高出按抗震设防烈度设计的结构强度。2）非弹性变形引起较小的能量耗散。3）在基准地面运动下,峰值位移都在允许范围内。对循环推覆荷载的分析显示,模型结构的位移延展比为4．50,强度系数约为6．0。     

Imaging-based detection of AAR induced map-crack damage in concrete structure

Imaging-based inspection methods are increasingly being employed for crack detection in concrete structures, because they provide quantitative information compared to inspections based solely on conventional visual approaches. However, efficient image analysis methods are needed. This study proposes the application of the grey level co-occurrence matrix (GLCM) texture analysis approach and an artificial neural network (ANN) classifier to obtain surface damage information, such as the total amount of superficial cracking, as well as the total length, and range of crack widths. These methods were applied to thermographic, visual colour and greyscale images of concrete blocks from CANMET that were exposed outdoors for ten years, as well as slabs from GRAI that were kept indoors, all specimens exhibiting various levels of alkali-aggregate reaction (AAR) damage. Results of the classifications show that the greyscale imagery performed fairly well, with an overall classification accuracy range of 72.3–76.5% for the CANMET blocks, and 68.7–75.3% for the GRAI slabs. Classifications using the colour imagery were slightly better than the greyscale imagery, with accuracies ranging from 71.4% to 75.2% for CANMET blocks and 70.9–72.0% for the GRAI slabs. The thermographic imagery, however, produced the highest overall classification accuracies, which range from 73.1% to 76.3% for the CANMET blocks and 74.2–76.9% for the GRAI slabs. The results show that all three types of imagery are relatively effective in characterizing and quantifying crack damage; however, the infrared thermography produced more accurate results compared to the visual colour, and greyscale images.     

MOFs 材料金属位点设计及沼气纯化应用研究

改变MOFs材料的中心金属能影响其气体的亲和性和双组份气体的吸附选择性（如比表面积,孔道结构,内部电场等）,本文合成并表征了M－DABCO系列（M＝Ni, Co, Cu, Zn） MOFs材料。并应用理想吸附溶液理论（Ideal Adsorbed Solution Theory,简称IAST）量化模拟了环境条件下双组分混合气体（组分比CO2：CH4＝40％：60％）的吸附选择性。 Ni－DABCO材料具有良好的CO2吸附性能和在环境条件下对CO2／CH4混合气体的吸附选择性。本文通过实验、表征及计算等来讨论中心金属对M－DABCO系列吸附位点的影响。