Nanocrystalline cellulose (NCC) is an emerging renewable nanomaterial that holds promise in many different applications, such as in personal care, chemicals, foods, pharmaceuticals, etc. By ...appropriate modification of NCC, various functional nanomaterials with outstanding properties, or significantly improved physical, chemical, biological, as well as electronic properties can be developed. The nanoparticles are stabilised in aqueous suspension by negative charges on the surface, which are produced during the acid hydrolysis process. NCC suspensions can form a chiral nematic ordered phase beyond a critical concentration, i.e. NCC suspensions transform from an isotropic to an anisotropic chiral nematic liquid crystalline phase. Due to its nanoscale dimension and intrinsic physicochemical properties, NCC is a promising renewable biomaterial that can be used as a reinforcing component in high performance nanocomposites. Many new nanocomposite materials with attractive properties were obtained by the physical incorporation of NCC into a natural or synthetic polymeric matrix. Simple chemical modification on NCC surface can improve its dispersability in different solvents and expand its utilisation in nano‐related applications, such as drug delivery, protein immobilisation, and inorganic reaction template. This review paper provides an overview on this emerging nanomaterial, focusing on the surface modification, properties and applications of NCC.
Machining of steel inherently generates high cutting temperature, which not only reduces tool life but also impairs the product quality. Conventional cutting fluids are ineffective in controlling the ...high cutting temperature and rapid tool wear. Further, they also deteriorate the working environment and lead to general environmental pollution. Cryogenic cooling is an environment friendly clean technology for desirable control of cutting temperature. The present work deals with experimental investigation in the role of cryogenic cooling by liquid nitrogen jet on cutting temperature, tool wear, surface finish and dimensional deviation in turning of AISI-4037 steel at industrial speed-feed combination by coated carbide insert. The results have been compared with dry machining and machining with soluble oil as coolant. The results of the present work indicate substantial benefit of cryogenic cooling on tool life, surface finish and dimensional deviation. This may be attributed mainly to the reduction in cutting zone temperature and favorable change in the chip–tool interaction. Further it was evident that machining with soluble oil cooling failed to provide any significant improvement in tool life, rather surface finish deteriorated.
In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. ...Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluids changes the performance of machining operations because of their lubrication, cooling, and chip flushing functions but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intrusiveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors.
This paper deals with experimental investigation on the role of MQL on tool wear and surface roughness in turning AISI-4340 steel at industrial speed-feed combination by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip–tool and work–tool interaction.
This paper presents the effects of minimum quantity lubrication (MQL) by vegetable oil-based cutting fluid on the turning performance of low alloy steel AISI 9310 as compared to completely dry and ...wet machining in terms of chip–tool interface temperature, chip formation mode, tool wear and surface roughness. The minimum quantity lubrication was provided with a spray of air and vegetable oil. MQL machining was performed much superior compared to the dry and wet machining due to substantial reduction in cutting zone temperature enabling favorable chip formation and chip–tool interaction. It was also seen from the results that the substantial reduction in tool wears resulted in enhanced the tool life and surface finish. Furthermore, MQL provides environment friendliness (maintaining neat, clean and dry working area, avoiding inconvenience and health hazards due to heat, smoke, fumes, gases, etc. and preventing pollution of the surroundings) and improves the machinability characteristics.
The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life ...but also impairs the product quality. Application of cutting fluids changes the performance of machining operations because of their lubrication, cooling, and chip flushing functions. But the conventional cutting fluids are not that effective in such high production machining, particularly in continuous cutting of materials likes steels. Minimum quantity lubrication (MQL) presents itself as a viable alternative for turning with respect to tool wear, heat dissipation, and machined surface quality. This study compares the mechanical performance of MQL to completely dry lubrication for the turning of AISI-1040 steel based on experimental measurement of cutting temperature, chip reduction coefficient, cutting forces, tool wears, surface finish, and dimensional deviation. Results indicated that the use of near dry lubrication leads to lower cutting temperature and cutting force, favorable chip–tool interaction, reduced tool wears, surface roughness, and dimensional deviation.
Currently there is much discussion regarding the impact of climate change and the vagaries of the weather, in particular extreme weather events. The Himalayas form the main natural water resource of ...the major river systems of the Indian region. We present a brief review of the available information and data for extreme rainfall events that were experienced in different sectors of the Himalayas during the last 137 years (1871–2007). Across the entire Himalayas, from east to west, there are now 822 rainfall stations. There was an increase in the rainfall station network from 1947 onwards, especially in the Nepal and Bhutan Himalayas. Extreme one-day rainfall has been picked out for each station irrespective of the period for which data are available. The decadal distribution of these extreme one-day rainfalls shows that there is a considerable increase in the frequencies during the decades 1951–1960 to 1991–2000, whereas there is a sudden decrease in the frequencies in the present decade during 2001–2007, indicating the need to understand the response of the systems to global change and the associated physical and climatological changes. This is essential in terms of preserving this natural resource and to encourage environmental management and sustainable development of mountain regions.Citation Nandargi, S. & Dhar, O. N. (2011) Extreme rainfall events over the Himalayas between 1871 and 2007. Hydrol. Sci. J.56(6), 930–945.
3D sensors offer depth sensing that may be used for task-specific data processing and computational modeling. Many existing methods for human identification using 3D depth sensors primarily focus on ...Kinect data, where the range is very limited. This work considers a 3D long-range Lidar sensor for far-field imaging of human subjects in 3D Lidar full motion video (FMV) of "walking" action. 3D Lidar FMV data for human subjects are used to develop computational modeling for automated human silhouette and skeleton extraction followed by subject identification. We propose a matrix completion algorithm to handle missing data in 3D FMV due to self-occlusion and occlusion from other subjects for 3D skeleton extraction. We further study the effect of noise in the 3D low resolution far-field Lidar data in human silhouette extraction performance of the model. Moreover, this work addresses challenges associated with far-field 3D Lidar including learning with a limited amount of data and low resolution. Moreover, we evaluate the proposed computational algorithm using a gallery of 10 subjects for human identification and show that our method is competitive with the state-of-the-art OpenPose and V2VPose skeleton extraction models using the same dataset for human identification.
In metal industries, the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. But the use of cutting fluid generally causes economy of tools ...and it becomes easier to keep tight tolerances and to maintain workpiece surface properties without damages. Because of them some alternatives has been sought to minimize or even avoid the use of cutting fluid in machining operations. Some of these alternatives are dry machining and machining with minimum quantity of lubrication (MQL). This paper deals with experimental investigations in the role of MQL on cutting temperature, chip formation and product quality in turning AISI-1040 steel at different industrial speed-feed combinations by uncoated carbide insert. The results have been compared with dry machining and machining with soluble oil as coolant. The experimental results indicate that such MQL enables substantial reduction in the cutting temperature, dimensional inaccuracy depending upon the levels of the cutting velocity and feed rate. It was also noted that the chip formation and chip–tool interaction become more favorable under MQL condition. Therefore, it appears that MQL, if properly employed, not only provides environment friendliness but can also improve the machinability characteristics.
The relatively high dislocation density of HgCdTe material grown on CdTe/Si by MBE has become a major roadblock toward achieving high operability of LWIR HgCdTe/Si FPAs. One approach to mitigate this ...problem is to reduce the dislocation density of the underlying CdTe/Si composite substrate, which is currently about two orders higher than that of bulk CdZnTe. In this paper, we will report on our systematic study of in-situ cyclic annealing of CdTe/Si and its impact on dislocation density. We observed a two orders of magnitude reduction of dislocation density on in-situ annealed CdTe/Si with respect to un-annealed CdTe/Si. The degree of reduction is proportional to the number of annealing cycles applied during the growth run. Depth profiling of the dislocation density of CdTe/Si layers with and without in-situ cyclic annealing has also been investigated. We do not observe the conventional 1/
h behavior of the dislocation density for layers grown without any thermal treatment. In contrast, for the layer grown with in-situ cyclic annealing, we observe an exponential decay of dislocation density as a function of layer thickness. However, we also observe a saturation of dislocation density in low to mid 10
5
cm
−2, regardless of the annealing temperature and number of the cycles used during annealing.
PDF
