Journal of Engineering Research and Reports

The paper is focused on the glue voids reduction of quad-flat no-leads (QFN) devices evaluated on different die attach machine platforms. The evaluation was narrowed-down into two main die attach machines with the objective of attaining the best performance in terms of reducing or eliminating the glue voids. Glue voids were quantified and only die attach Machine B was able to satisfy the specification. The study used analysis of variance on the two machines and presented the effect of machine selection on glue voids reduction. For future works, the selected die attach machine could be used for devices with critical requirement.

Understanding the dynamics, patterns, and probabilities associated with the correlates of crime is a promising way to managing crime. In this study, a multinomial logistic regression was used to predict the propensity of individuals for committing particular crimes. The secondary data of 6702 prisoners was collated from Ghana Prisons Service for the purpose of the study. ANOVA and Brown-Forsythe robust tests of equality of means were employed, where the assumptions for homogeneity of variance were sustained and violated respectively. Pearson’s correlation matrix was also used in the analysis. Our findings showed that religious affiliation and educational level of convicts significantly affected the odds that they would commit a particular crime. Multinomial logistic regression analysis indicated that illiteracy significantly affected the odds that one would commit the crimes of manslaughter, rape, theft, causing harm, and issuing death threats. On the other hand, religious affiliation of an offender significantly affected the odds to commit the crime of murder. Educational level (r= -0.25; p< 0.05) and religious affiliation (r= -0.26; p<0.05) correlated negatively with crime. There were no significant differences in the mean score of crime across educational and religious levels. However, there were significant differences in the mean score of crime across age and gender. The mean difference from the post-hoc analysis showed a pattern of an initial rise in crime among the younger age group (8-25 years), a subsequent decline in the age group of 26-35, and a final surge in individuals beyond 35 years that did not surpass the initial peak. Females (M: 6.89, SD: 1.253) were found to have lower crime incidence than males (M: 7.43, SD: 3.008) for all crimes considered in this study. We recommend that Ghana’s Prison Service consider incorporating further demographic information of inmates in order to support research; which could help identify avenues for the amelioration of crime locally.

Although corona discharge is notorious for its detrimental effects, it is also used in many beneficial practical applications. Despite the existence of a variety of sophisticated theoretical and experimental methods for investigating corona discharge, we explore yet a much simpler method that relies on the use of Dimensional Analysis (DA). The DA method does not demand profound knowledge of the underlying phenomenon or its governing equations, as it only needs the correct identification of the variables influencing the phenomenon, and the specification of their physical dimensions. The classical and well-known Gauss-Jordan elimination method is compared with other matrix-oriented computational approaches in analyzing the pertinent dimensional system. This method relies upon solution-preserving elementary row operations, i.e., operations that one can use on a matrix without spoiling the solution set for an associated matrix equation. A distinct advantage of this method is that it does not pre-suppose a particular value of the matrix rank but tackles the task of determining this rank while proceeding towards its ultimate result. Moreover, this method can also be used to find the inverse of a regular (invertible) matrix or to determine the solution (if any) of a system of linear equations. As a bonus, novel results of numerical investigations of bases, regimes, and dimensionless products are extensively presented in this paper. A remarkable observation made herein is that the set of variables pertinent for a particular phenomenon cannot be arbitrarily partitioned into basis (input) variables and regime (output or isolated) variables. The paper running example deals with expressing a specific variable, viz. ozone generation rate per unit length of wire (r⁰) through dimensionless products in terms of a set of determining or influencing variables.

This study aims to study the influencing factors of traffic accidents in undersea tunnels and establish a prediction model of undersea tunnel traffic accidents. Through face-to-face inquiry and telephone survey, the relevant information of drivers who had traffic accidents in Jiaozhou Bay undersea tunnel from 2018 to 2019 was obtained, and the relevant information of citizens passing through Jiaozhou Bay undersea tunnel was obtained by posting questionnaires on the Internet. Based on whether there were traffic accidents in undersea tunnel, the drivers with undersea tunnel driving experience were divided into accident group and control group. Through the single factor analysis of the data, it is found that drinking, bad driving habits, having traffic accident experience, speeding and other thirteen factors have an important impact on the occurrence of traffic accidents undersea tunnel. Multivariate analysis was carried out on thirteen factors with significant influence, and a model for predicting the probability of accidents in undersea tunnels was established. Five influencing factors of speeding, the following distance is too small, carelessness, illegal lane change and having traffic accidents experience entered the model, with OR values of 7.11(2.94-18.90), 2.35(1.17-4.08), 3.99(1.23-7.45), 2.68(1.15-6.39) and 3.95(1.78-6.11). The occurrence of accidents in undersea tunnel is related to the length of the tunnel and the traffic flow. For an undersea tunnel with a length of 7 km and an average daily traffic flow of 50000 vehicles, the number of daily traffic accidents is 1.96. The driver’s violations and the driver’s carelessness are the main factors in undersea tunnel traffic accident. In order to improve the traffic safety of undersea tunnel, government departments should step up enforcement against traffic violations. In addition, the undersea tunnel management department needs to consider taking measures to improve the harsh and monotonous environment in the tunnel. This study provides an empirical basis for the prevention of traffic accidents in undersea tunnels.

This research was undertaken to determine the effects of corrosion on material performance using mild steel and Aluminum as selected material in seawater media. The result from the experiment showed higher corrosion rate in uncoated mild steel coupon as higher corrosion rate ranges from 0.0494 mmpy, 0.0565 mmpy, and 0.0656 mmpy was evident, while a reduction in corrosion rate from 0.0369mmpy, 0.0432 mmpy and 0.0452mmpy was observed in the fourth week, fifth week and sixth week. Corrosion rate for coated mild steel ranges from 0.0396 mmpy in the first week and reduces to 0.0333 mmpy and continually reduces to 0.0206 mmpy in the sixth week. From the hardness testing device using MITECH 320, uncoated Mild steel metal specimen gave an average Brinell hardness reading of 112 before immersion and 105 after immersion to seawater. Also, the tensile strength of the uncoated mild steel specimen deteriorated from 414 Mpa before immersion to 403Mpa after immersion to seawater media. Also, uncoated Aluminum specimen gave a brinell average reading of 163 before immersion and 152 after immersion to the seawater media. Likewise, the tensile strength result of the aluminum specimen gave 776M pa before immersion and 744 Mpa after immersion to the seawater media. The overall result from weight loss technique and metal hardness using MITECH 320 showed aluminum metal is more resistive to corrosion attack.