造成印刷成品率低的重要因素分析

本文以Thomson印刷厂印刷生产为例,着重讨论了如何减少印刷品损耗和避免印刷成品数量不足的问题.为了确定印刷过程中造成印品不足的工序和因素,本研究跟踪了十种不同印刷样品的生产过程,研究讨论了造成印刷品损耗、导致印刷成品不足的各种印刷问题.为了解决这些问题,需要了解印刷工作原理以及减少损耗的方法.本文为研究印刷生产和加工过程中的常见问题,减少印刷浪费提供了借鉴.     

Analytical modeling of the ion number fluctuations in biological ion channels

Ion channels are transmembrane proteins that regulate and maintain the ionic concentrations across the cell membrane. Modeling the atomistic-level ionic flux through these channels is crucial for the understanding of several neurological diseases and related pharmaceutical discoveries. Experimental techniques now provide information about the channel's physical structure which helps in developing realisticion transport models. Ions entering a channel follow different trajectories as they traverse the channel; each associated with a certain probability. Quantities that explain these trajectories are the translocation and return probabilities, average lifetime, and spectral density (an experimentally accessible parameter) of ion number fluctuations. Theoretical analysis of ion transport has been limited to low-resolution continuum diffusion-based or kinetic-based models. Such analytical models fail to include key factors affecting the ionic conduction. In this paper, we extend previous models by an electro-diffusion model incorporating the effects of electric field, energy barrier, and rate-limited association/dissociation of ions with surface charges inside the channel. Survival probability and spectral density are derived from the analytical model.     

Nanopatterned cadmium selenide Langmuir-Blodgett platform for leukemia detection

We present results of the studies relating to preparation of Langmuir-Blodgett (LB) monolayers of tri-n-octylphosphine oxide-capped cadmium selenide quantum dots (QCdSe) onto indium-tin oxide (ITO) coated glass substrate. The monolayer behavior has been studied at the air-water interface under various subphase conditions. This nanopatterned platform has been explored to fabricate an electrochemical DNA biosensor for detection of chronic myelogenous leukemia (CML) by covalently immobilizing the thiol-terminated oligonucleotide probe sequence via a displacement reaction. The results of electrochemical response studies reveal that this biosensor can detect target DNA in the range of 10(-6) to 10(-14) M within 120 s, has a shelf life of 2 months, and can be used about 8 times. Further, this nucleic acid sensor has been found to distinguish the CML-positive and the control negative clinical patient samples.     

Mobility-limiting mechanisms in polar semiconductor heterostructures

The mechanisms controlling the carrier mobility of two-dimensional electron gases (2DEGs) in ultrathin polar semiconductor heterostructures, such as III–V nitrides, have been analyzed. In_xAl_1?xN/AlN/GaN heterostructures with different AlN layer thicknesses have been investigated. These structures can be considered a very good benchmark for the analyses of III–V nitrides, due to the possibility of modulating the strain by varying the In composition. In order to determine an estimate of the mobility, charged dislocation and remote surface roughness scattering lifetimes have been calculated. Atomic force microscopy and scanning tunneling microscopy analyses have been used to measure the parameters required for the lifetime calculation, such as surface roughness, correlation length and dislocation density, and the total mobility has thus been calculated without the need of any a priori assumptions on the values of these parameters. The mobility of In_xAl_1?xN/AlN/GaN heterostructures has been measured at room temperature and liquid nitrogen temperature by the Hall effect. A comparison between the calculated and the Hall-effect-measured mobilities allowed us to establish, without using any ad hoc assumptions or fitting parameters, that the remote surface roughness is the most effective factor in controlling the transport properties of 2DEGs in nitride-based heterostructures at low temperature.     

Design of self-tuning controllers for a two terminal HVDC link

This paper presents the design of self-tuning controllers for a two terminal HVDC link. The controllers are designed utilizing a novel discrete-time converter model based on multirate sampling. The nature of converter firing system necessitates the development of a two-step ahead self-tuning control strategy. A two terminal HVDC system study has been carried out to show the effectiveness of the control strategies proposed which include the design of minimum variance controller, pole assigned controller and PLQG controller. The coordinated control of a two terminal HVDC system has been established deriving the signal from inverter end current and voltage which has been estimated based on the measurements of rectifier end quantities only realized through the robust reduced order observer. A well known scaled down sample system data has been selected for studies and the controllers designed have been tested for worst conditions. The performance of self-tuning controllers has been evaluated through digital simulation.     

Pot and field studies on bioremediation of p-nitrophenol contaminated soil using Arthrobacter protophormiae RKJ100

Biodegradation of p-nitrophenol (PNP), a priority pollutant, was studied as a model system for bioremediation of sites contaminated with nitroaromatic/organic compounds. Bioremediation of PNP-containing soil was first carried out in pots using immobilized and free cells of Arthrobacter protophormiae RKJ100 in order to ascertain the role of a suitable carrier material. Results showed that stability of the introduced strain was enhanced upon immobilization and that the rate of PNP depletion decreased with increasing depth of soil. Small-scale field studies (in one square meter plots) were then conducted in which PNP-contaminated soil from an agricultural field was bioaugmented with strain RKJ100 under natural environmental conditions. PNP was totally depleted in 5 days by immobilized cells, whereas free cells were able to deplete 75% of PNP in the same time period. The fate of the released strain as monitored by plate counts, hybridization studies, and real-time polymerase chain reaction revealed fairly stable population of the cells upon immobilization on corncob powder throughout the period of study.     

Electric power system reliability criteria determination in adeveloping country-an investigation in Nepal

This paper examines the problems associated with using power system reliability cost/worth techniques in a developing country, and presents methods to develop planning criteria incorporating explicit recognition of reliability worth. The developed methods are illustrated by application to the Nepal Integrated Electric Power System     

MHD 3D free convective flow of nanofluid over an exponentially stretching sheet with chemical reaction

This paper deals with a problem where the effect of variable magnetic field and chemical reaction on free convective flow of an electrically conducting incompressible water based nanofluid over an exponentially stretching sheet has been investigated. In the present study, Buongiorno model associated with Brownian motion and thermophoretic diffusion is employed to describe the heat transfer enhancement of nanofluids. Some suitable similarity transformations reduced the governing boundary layer non-linear partial differential equations into a set of ordinary non-linear differential equations. The transformed equations are then solved numerically using fourth order Runga-Kutta method along with Shooting technique. The major outcomes of the present study is that the magnetic field impedes the fluid motion while thermal as well as mass buoyancy forces accelerate it, the thermophoretic diffusion enhances dimensionless fluid temperature as well as concentration leading to thicker thermal and concentration boundary layers. On the other hand, concentration exponent, Brownian motion parameter and chemical reaction parameter exhibit reverse trend on temperature and concentration. In addition, the presence of magnetic field under the influence of thermal as well as mass buoyancies supports to reduce the rate of heat transfer as well as wall shear stress while the first order chemical reaction develops a thinner concentration boundary layer.     

Defect detection in deep groove ball bearing in presence of external vibration using envelope analysis and Duffing oscillator

This paper deals with detection of local defects existing on races of deep groove ball bearing in the presence of external vibrations using envelope analysis and Duffing oscillator. Experiments have been carried out using a test rig for capturing the vibration signals of test bearing. The external vibration has been imparted to the housing of the test bearing through electromechanical shaker. In envelope analysis the centre frequency has been selected using the spectral kurtosis for the filters length of 32 and 64 for different bandwidths. Through this study, it has been revisited and confirmed that the defect detection in envelope analysis mainly depends on the selection of centre frequency and bandwidth. The spectra of selected centre frequency with several bandwidths have been studied and compared for identification of defective frequency. The system defined by the Duffing equation entered into the periodical state from the chaotic state at the critical value of disturbing periodic force in the presence of defective bearing signal. The state change has been identified using the phase plane trajectories and Lyapunov exponents of Duffing equation. It is worth to mention here that envelope spectrum reveals the information about the defect frequencies and their harmonics. However, the Duffing oscillator only confirms the presence of defect frequencies by indicating closed phase plane trajectories and negative Lyapunov exponents. Authors believe that for speedy assessment about the presence of defects on races of rolling element bearings, the use of Duffing oscillator may be preferred.     

Mechanical Properties and Wear Behavior of Zn and MoS<Subscript>2</Subscript> Reinforced Surface Composite Al- Si Alloys Using Friction Stir Processing

Friction stir processing (FSP) is a novel process for refinement of microstructure, improvement of material’s mechanical properties and production of surface layer composites. In present investigation, composite reinforced with using Zn/ MoS₂ powder in as-cast alloy were developed at tool rotational speed of 664 rpm and tool transverse speed of 26 mm/min using FSP. Microstructural observation of MoS₂/Zn reinforced composites confirmed the fine and equiaxed grains in the stir zone (SZ) and distribution of fine reinforced particles of MoS₂/Zn in SZ. Moreover, agglomeration of MoS₂/Zn particles were not observed. The ultimate tensile strength was measured to be 113 ± 9 and 82 ± 7 MPa for MoS₂and Zn reinforced Al-Si alloy, respectively. The sliding wear was studied using pin-on-disk tribometer and it was found that FSP enhanced the wear resistance of the as-cast alloy. The MoS₂ reinforced composite showed superior wear resistance than Zn reinforced composite and base material. To understand the acting wear mechanism, the field emission scanning electron microscope (FESEM) of worn out surfaces were performed.