Dynamic Analysis of a Rotating Shaft Subject to the Double Cutting Force and Time-varying Mass Effects of the Rod

AbstractThis paper investigates the dynamic behaviors of a rotating shaft subjected to the double cutting force and time-varying mass effects. The Timoshenko beam theory is used to model the rotating shaft, and the general boundary condition is assumed as the clamped-hinged supports. This system is used to simulate the manufacture process of the double turret CNC lathes, and the mass of the rod which is reduced gradually in cutting process. The system equations of motion are derived based on the global assumed mode method, and the dynamic responses of the system are obtained by Runge-Kutta numerical method. The transformation matrix is derived to make the equation of motion completing the boundary geometric constraints. The numerical results compare the dynamic response in different moving speeds and skew angles of the cutting forces with/without the time-varying mass effects. Additionally, this paper compares the response with single cutting force and double force. The results show that the double moving force system can reduce not only the machining time but also the amplitude of shaft vibration

RNA : protein and protein : Protein interactions in the virions of southern bean mosaic virus : (isometric plant viruses, stabilizing interactions, capsid structure)

Virions of southern bean mosaic virus (SBMV), a small RNA-containing isometric plant virus, are stabilized with strong linkages between the coat protein subunits mediated through divalent metal ions (magnesium, calcium) and hydrophobic interactions. Virion treatments interfering with these inter-subunit linkages markedly alter the conformation and stability of the SBMV capsid. The virion capsid is composed of the entire complement of the viral protein, including a small proportion of stable coat protein dimers formed with covalent linkages between the epsilon-amino groups of the lysyl residues. The viral RNA is located within the capsid but 'loosely' contacts only one-third of the total coat protein. A tentative structural model of SBMV virions based upon physico-chemical and morphological considerations is proposed.O. P. SEHGAL and C.H. HSU, Department of Plant Pathology, University of Missouri, Columbia, MO

Synthesis of Cobalt Nanowires on Porous Anodic Alumina Template Using Electrochemical Deposition

Electrochemical deposition has been widely used for synthesis of metal nanowires (NWs) on the porous template. In this paper, the effect of potential and electrolyte concentration on cobalt (Co) NWs formation through porous anodic alumina template has been investigated using direct-current electrodepostion at 0.75~2 V together with the high 0.5 M and low 0.1 M cobalt sulfurate based electrolyte. Scanning electron microscopy and grazing incidence X-ray diffraction were used to examine the nanostructure, morphology and phase of Co NWs. The current vs time curve was recorded for understanding the growth behavior. Too low potential of 0.75 V is not favored for Co NWs formation due to insufficient driving force while too high potential of 2 V ruins the NWs growth owing to hydrogen generation in reduction reaction. The uniform crystalline Co NWs can be obtained by the proper potential of 1V and concentration of 0.5 M at an average growth rate of 964 nm/min

Thermal and electrical study on ac light-emitting diode with quantum wells under various cooling rate

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The conventional Shockley equation is inappropriate to describe the relationship between the current density and the forward voltage drop across the p-n junction in LED (light-emitting diode) with multiple quantum wells. In the present study, a semi-empirical model based on the existing experimental measurements is proposed to evaluate the forwards voltage drop under given current density and temperature. The numerical model then is employed to investigate the electrical and temperature fields on ac LED with multiple quantum wells under various cooling rate. The numerical results reveal that the temperature of the LED oscillates under ac electrical potential. The temperature increases due to the heat generation arising from the electrical current across the p-n junction when the electrical potential exceeds the threshold voltage. Otherwise, there is no electrical current and thus the temperature decreases due to the effect of the cooling device. Both light-emitting power and maximum temperature increase as expected when the applied ac electrical potential increases. Fortunately, the temperature of the LED can be efficiently controlled by increasing the cooling rate. Although increasing the cooling rate would decrease the light-emitting power, the influence is not significant.cf201

Multi-Threshold Level Set Model for Image Segmentation

A multi-threshold level set model for image segmentations is presented in the paper. The multi-threshold level set formulation uses a speed function for stopping the locations of the active contours. The speed function with multiple thresholds is designed for detecting boundaries of multiple regions of interest (ROI) in images. These thresholds can be automatically obtained by Fuzzy C-means method. The experimental results show that the proposed method is able to capture boundaries of multiple regions of interest

Crystallization and preliminary X-ray diffraction analysis of PAT, an acetyltransferase from Sulfolobus solfataricus

PAT is an acetyltransferase from the archaeon Sulfolobus solfataricus that specifically acetylates the chromatin protein Alba. The enzyme was expressed, purified and subsequently crystallized using the sitting-drop vapour-diffusion technique. Native diffraction data were collected to 1.70 angstrom resolution on the BL13C1 beamline of NSRRC from a flash-frozen crystal at 100 K. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 44.30, b = 46.59, c = 68.39 angstrom

Effects of wood particle size and mixing ratios of HDPE on the properties of the composites

The main goal of this research is to innovate wood-plastic composites by using various wood particle sizes and different mixture ratios (weight ratio) of HDPE. (High Density Polyethylene). After mixing the wood particles (recycled wood waste) and the plastic powder, we use a molding and pressing process to make composites with a thickness of 12 mm. By doing so, the wood particle content can be increased to 75%. This kind of composite provides excellent dimensional stability, its moisture content is under 2.5%, and the thickness swelling rate after 24 hr water absorption is under 7.5%. The maximum static bending strength of this composite reaches 20.7 N/mm(2), and is better than that of general commercial particleboards. The composite made of larger sized wood particles has better strength properties. In addition, when the plastic content ratio increases, the dimensional stability of the composite will increase as well. After the soaking process in boiling water, the static bending strength of wet composite remained at 50%; this shows the good weather resistance of the composite. The surface veneer overlaid peeling strength of the composite showed 1.02-1.63 N/mm. After the evaluation of processing, cost of material and strength properties of the composite, we would suggest that the use of 70% of wood particles and 30% of plastic powder is practical to produce proper sized composites

Identification of differentially expressed genes induced by Bamboo mosaic virus infection in Nicotiana benthamiana by cDNA-amplified fragment length polymorphism

Background: The genes of plants can be up- or down-regulated during viral infection to influence the replication of viruses. Identification of these differentially expressed genes could shed light on the defense systems employed by plants and the mechanisms involved in the adaption of viruses to plant cells. Differential gene expression in Nicotiana benthamiana plants in response to infection with Bamboo mosaic virus (BaMV) was revealed using cDNA-amplified fragment length polymorphism (AFLP). Results: Following inoculation with BaMV, N. benthamiana displayed differential gene expression in response to the infection. Isolation, cloning, and sequencing analysis using cDNA-AFLP furnished 90 cDNA fragments with eight pairs of selective primers. Fifteen randomly selected genes were used for a combined virus-induced gene silencing (VIGS) knockdown experiment, using BaMV infection to investigate the roles played by these genes during viral infection, specifically addressing the means by which these genes influence the accumulation of BaMV protein. Nine of the 15 genes showed either a positive or a negative influence on the accumulation of BaMV protein. Six knockdown plants showed an increase in the accumulation of BaMV, suggesting that they played a role in the resistance to viral infection, while three plants showed a reduction in coat protein, indicating a positive influence on the accumulation of BaMV in plants. An interesting observation was that eight of the nine plants showing an increase in BaMV coat protein were associated with cell rescue, defense, death, aging, signal transduction, and energy production. Conclusions: This study reports an efficient and straightforward method for the identification of host genes involved in viral infection. We succeeded in establishing a cDNA-AFLP system to help track changes in gene expression patterns in N. benthamiana plants when infected with BaMV. The combination of both DNA-AFLP and VIGS methodologies made it possible to screen a large number of genes and identify those associated with infections of plant viruses. In this report, 9 of the 15 analyzed genes exhibited either a positive or a negative influence on the accumulation of BaMV in N. benthamiana plants