MONITORING OF THE STENCIL PRINTING PROCESS USING A MODIFIED REGRESSION RESIDUAL CONTROL CHART: AN EMPIRICAL STUDY

This paper aims at developing a regression residual control chart to economically detect the abnormal patterns of the stencil printing process (SPP), so as to predict significant deviations that might result in nonconforming products. The SPP is widely recognized as the main contributor of soldering defects in a surface mount assembly (SMA). The earlier those abnormal conditions can be detected in the SPP stage, the less expensive the defect correction costs. Shewhart control chart is frequently used to monitor the amount of solder paste volume. However, its results can be error-prone since the solder paste volume is significantly affected by other process factors. For developing the proposed control chart, a 3^8-3 experimental design was first conducted and validated to formulate the relationship between the control variables and the SPP response. Eight process factors for SPP were initially defined, including stencil thickness, component pitch, aperture area, snap-off height, squeegee speed, squeegee pressure, solder paste viscosity, and solder paste type. The control variables of the SPP can be expressed as a linear regression function, and a regression residual control chart can then be constructed using the significant variables through the results of ANOVA analysis. Finally, the proposed control chart is employed to detect out-of-control conditions of the SPP. A Monte-Carlo simulation and an empirical evaluation were also carried out to demonstrate the effectiveness of the proposed methodology. The empirical evaluation shows that the proposed regression residual control chart provides approximately 90% of detection accuracy for the SPP

Extend the debt as it is not deeply out-of-the-money

In this paper, we modify the extendible debts model proposed in Longstaff (1990) to help relieve the moral hazard problem induced in the original model. In Longstaff¡¦s model, extending the maturity of the defaulted debts gives the borrower an incentive to default even if the borrower is insolvent. In this paper, we argue that the debt should not be extended if it is defaulted severely. We have shown that the extendible debt valuation can be obtained by the compound option pricing besides the PDE approach. We also have derived the fair interest rate of the extendible debts in this paper.

N,N′-Bis(pyridin-2-yl)benzene-1,4-dicarboxamide

Mol­ecules of the title compound, C18H14N4O2, are located around an inversion center and connected into chains in the crystal via inter­molecular N—H⋯N hydrogen bonds generating an R 2 2(8) motif

Biological actions and molecular effects of resveratrol, pterostilbene, and 3′-hydroxypterostilbene

AbstractStilbenes are a class of polyphenolic compounds, naturally found in a wide variety of dietary sources such as grapes, berries, peanuts, red wine, and some medicinal plants. There are several well-known stilbenes including trans-resveratrol, pterostilbene, and 3′-hydroxypterostilbene. The core chemical structure of stilbene compounds is 1,2-diphenylethylene. Recently, stilbenes have attracted extensive attention and interest due to their wide range of health-beneficial effects such as anti-inflammation, -carcinogenic, -diabetes, and -dyslipidemia activities. Moreover, accumulating in vitro and in vivo studies have reported that stilbene compounds act as inducers of multiple cell-death pathways such as apoptosis, cell cycle arrest, and autophagy for chemopreventive and chemotherapeutic agents in several types of cancer cells. The aim of this review is to highlight recent molecular findings and biological actions of trans-resveratrol, pterostilbene, and 3′-hydroxypterostilbene

The Internal Audit Performance: The Effectiveness of ERM and IT Environments

The purpose of this study is to examine the factors determining the performance of the internal audit (IA) in the context of internal auditors’ work environments. This includes Enterprise Risk Management (ERM) implementation, the Enterprise Resource Planning (ERP) system, the use of auditing software and the internal auditors’ IT (information technology) competence. Although a number of recent studies have reported tremendous changes in the roles of the IA, there is still little research on the influential factors of IA implementation and its effectiveness from a contextual perspective. This paper develops and tests a theoretical framework with samples from Taiwan. Data were analyzed using the structural equation model (SEM). This research confirms that the complete ERM implementation and effectiveness of ERP implementation have significant impacts on the performance of IA. It also highlights the importance of internal auditors’ IT competence in improving the performance of IA

Alleviating Interference through Cognitive Radio for LTE-Advanced Network

In the LTE-Advanced network, some femtocells are deployed within a macroecell for improving throughput of indoor user equipments (UEs), which are referred to as femtocell UEs (FUEs). Cross-tier interference is an important issue in this deployment, which may significantly impact signal quality between Macrocell Base Stations (MBSs) and Macrocell User Equipments (MUEs), especially for MUEs near the femtocell. To relieve this problem, the Third Generation Partnership Project Long Term Evolution-Advanced (3GPP LTE-Advanced) de fined the cognitive radio enhanced femtocell to coordinate interference for LTE-Advanced Network. Cognitive radio femtocells have the ability to sense radio environment to obtain radio parameters. In this paper, we investigated the performance of existing schemes based on fractional frequency reuse. Therefore, we proposed a scheme with cognitive radio technology to improve the performance of fractional fre-quency reuse scheme. Simulation results showed that our scheme can effectively enhance average downlink throughput of FUEs as well as the total downlink throughput in LTE-Advanced Networks