Development of a Control Strategy for Monitoring the Delaminating Damage in Drilling Of Carbon Composite Laminates

Composite materials have attractive features, such as high strength to weight ratio and high stiffness to weight ratio. However, they are easily damaged during machining operations. A typical damage is delamination, which can occur when fiber reinforced composite laminates are drilled. Control of delamination is critical for the utilization of composite materials. This research seeks to develop a technique to control inter-ply delaminations during the drilling of laminated composites. A statistical factorial design technique is used to develop a model that relates the feed rate, cutting speed, and tool size to the acoustic parameters. A control algorithm is built from the model. The algorithm is used to modify the instantaneous feed rate in order to maintain the acoustic energy below a threshold value. This control strategy is effective in limiting the area of delamination. However, using high cutting speeds avoid the delamination of materials, but leads to high production costs due to excessive tool wear.Keywords: Composite Laminates, Drilling, Damage, Acoustic Emission

Quasi-Automatic Monitoring System For Turning Operation Using Acoustic Emission Signal Response And Factorial Design Method

This work discusses the generation of a quasi monitoring system intended for an operator to change cutting tool during turning operation. The monitoring system uses the effects of turning va riables on acoustic emission signal responses and factorial experimental design approach. In cutting operations, acoustic emission provides useful information concerning the tool wear condition because of the fundamental differences between its source mechanisms in the rubbing friction on the wear land of the single point tool. In this study, effects of cutting speed, feed and tool condition on the acoustic emission signal are investigated using acoustic emission's energy, amplitude, and frequency response and 23 factorial design for turning operation. Cutting tests were performed using high-speed steel under dry conditions. Calculated effects, standard errors at 95% confidence level, and models governing the acoustic emission response to the cutting conditions have been generated from the acoustic emission signal responses. The generated models revealed that acoustic energy response is affected by significant interactions between cutting speed and feed, and insignificant interactions between cutting speed and tool condition, while the acoustic amplitude response is affected by insignificant interactions among cutting speed, feed, and tool condition. These results suggest that acoustic emission's energy and amplitude responses could be used to control the cutting speed and feed during turning operation, thus prolonging the life of the cutting tool.Journal of Science & Technology (Ghana) Vol. 27 (2) 2007: pp. 107-12

Tackling Exascale Software Challenges in Molecular Dynamics Simulations with GROMACS

GROMACS is a widely used package for biomolecular simulation, and over the last two decades it has evolved from small-scale efficiency to advanced heterogeneous acceleration and multi-level parallelism targeting some of the largest supercomputers in the world. Here, we describe some of the ways we have been able to realize this through the use of parallelization on all levels, combined with a constant focus on absolute performance. Release 4.6 of GROMACS uses SIMD acceleration on a wide range of architectures, GPU offloading acceleration, and both OpenMP and MPI parallelism within and between nodes, respectively. The recent work on acceleration made it necessary to revisit the fundamental algorithms of molecular simulation, including the concept of neighborsearching, and we discuss the present and future challenges we see for exascale simulation - in particular a very fine-grained task parallelism. We also discuss the software management, code peer review and continuous integration testing required for a project of this complexity.Comment: EASC 2014 conference proceedin

Modelling data of an urban drainage design using a Geographic Information System (GIS)database

This paper describes the development of a model to interface a planned urban drainage system with Geographic Information System (GIS)through the introduction of open-source tools; Auto Numbering and Get Elevation to extract essential data from GIS and Excel2GIS to bridge the output data between GIS and the drainage design program. Creating a range of essential data from digital database repositories aids the development of decision-support tools for urban planners in a simulation of different urban drainage scheme scenarios and moderates the interference with other infrastructure utilities. These tools, modelled with design software and GIS platform, are tested in two case studies; the results revealing essential improvements in accuracy of output, time taken to prepare and run the model and model presentation which visualised the hydraulic design results and global location of the drainage layout on an urban master plan. © 2019 Elsevier B.V

Cytomegalovirus MicroRNA Expression Is Tissue Specific and Is Associated with Persistence

MicroRNAs (miRNAs) are a class of small noncoding RNAs involved in posttranscriptional regulation. miRNAs are utilized in organisms ranging from plants to higher mammals, and data have shown that DNA viruses also use this method for host and viral gene regulation. Here, we report the sequencing of the small RNAs in rat cytomegalovirus (RCMV)-infected fibroblasts and persistently infected salivary glands. We identified 24 unique miRNAs that mapped to hairpin structures found within the viral genome. While most miRNAs were detected in both samples, four were detected exclusively in the infected fibroblasts and two were specific for the infected salivary glands. The RCMV miRNAs are distributed across the viral genome on both the positive and negative strands, with clusters of miRNAs at a number of locations, including near viral genes r1 and r111. The RCMV miRNAs have a genomic positional orientation similar to that of the miRNAs described for mouse cytomegalovirus, but they do not share any substantial sequence conservation. Similar to other reported miRNAs, the RCMV miRNAs had considerable variation at their 3′ and 5′ ends. Interestingly, we found a number of specific examples of differential isoform usage between the fibroblast and salivary gland samples. We determined by real-time PCR that expression of the RCMV miRNA miR-r111.1-2 is highly expressed in the salivary glands and that miR-R87-1 is expressed in most tissues during the acute infection phase. Our study identified the miRNAs expressed by RCMV in vitro and in vivo and demonstrated that expression is tissue specific and associated with a stage of viral infection

Designing a Mechanical System That Will Be Used To Extract and Separate Lemon Grass Oil

ABSTRACT Lemon grass is broadly used in medicine, perfumery industry, vitamin A manufacturing and pharmaceuticals. The need for lemon grass oil, especially in human health and its problem of extracting the oil, have directed this paper in designing a mechanical system that will be used to extract and separate lemon grass oil. The extraction of essential oil from lemon grass was done using direct steam distillation process. In all, three concepts were developed based on the orientation of the condensers, source of power, and method of oil production. The three (3) concepts were evaluated and the best concept was selected as the final design. Design analysis was performed on each part to determine their specification, the material to be used and manufacturing processes for the fabrication. Two tests were performed to determine the performance of machine and the quality of the oil produced. From the results, it can be established that the prototype machine developed can be used to extract lemon grass oil from the leaves. The efficiencies were then computed and favorable results were obtained. Also, the results obtained for the four tests responded positive given an indication of the pureness of the oil. It can then be concluded that the prototype machine developed can be used to extract lemon grass oil from the leaves and its efficiency ranges from 2.37 to 3.95 ml/kg and it is economically viable, effective and efficient

Delayed neutron emission measurements from fast fission of U-235 and Np-237

Experiments have been designed and conducted to measure the periods and yields of delayed neutrons from fast fission of {sup 235}U and {sup 237}Np. These measurements were performed in a pool type reactor using a fast flux in-core irradiation device. The energy dependent neutron flux spectrum within the irradiation device was characterized using a foil activation technique and the SAND-II unfolding code. Five delayed neutron groups were measured. The total yield (sum of the five group yields) for {sup 235}U was found to be 0.0141 {+-} 0. 0009. The total yield for {sup 237}Np was found to be 0.0102 {+-} 0. 0008. The total delayed neutron yield data were found to be in good agreement with previous measurements. The individual group yields reported here are preliminary and are being further refined

Charge multiplication effect in thin diamond films

Herein, we report on the enhanced sensitivity for the detection of charged particles in single crystal chemical vapour deposition (scCVD) diamond radiation detectors. The experimental results demonstrate charge multiplication in thin planar diamond membrane detectors, upon impact of 18MeV O ions, under high electric field conditions. Avalanche multiplication is widely exploited in devices such as avalanche photo diodes, but has never before been reproducibly observed in intrinsic CVD diamond. Because enhanced sensitivity for charged particle detection is obtained for short charge drift lengths without dark counts, this effect could be further exploited in the development of sensors based on avalanche multiplication and radiation detectors with extreme radiation hardnes

IL-22 mediates goblet cell hyperplasia and worm expulsion in intestinal helminth infection.

Type 2 immune responses are essential in protection against intestinal helminth infections. In this study we show that IL-22, a cytokine important in defence against bacterial infections in the intestinal tract, is also a critical mediator of anti-helminth immunity. After infection with Nippostrongylus brasiliensis, a rodent hookworm, IL-22-deficient mice showed impaired worm expulsion despite normal levels of type 2 cytokine production. The impaired worm expulsion correlated with reduced goblet cell hyperplasia and reduced expression of goblet cell markers. We further confirmed our findings in a second nematode model, the murine whipworm Trichuris muris. T.muris infected IL-22-deficient mice had a similar phenotype to that seen in N.brasiliensis infection, with impaired worm expulsion and reduced goblet cell hyperplasia. Ex vivo and in vitro analysis demonstrated that IL-22 is able to directly induce the expression of several goblet cell markers, including mucins. Taken together, our findings reveal that IL-22 plays an important role in goblet cell activation, and thus, a key role in anti-helminth immunity