Numerical simulation and optimization of fine-blanking process for copper alloy sheet

When the fine-blanking process is used, secondary grinding or processing can be omitted because the shear surface of fine-blanking parts can achieve almost zero fracture zone requirements. The primary objective of the fine-blanking process is to reduce the fracture zone depth and die roll zone width. This study used a 2.5-mm-thick central processing unit (CPU) thermal heat spreader as an example. Finite element analysis software was employed to simulate and optimize the main eight process parameters that affect the fracture zone depth and die roll zone width after fine-blanking: the V-ring shape angle, V-ring height of the blank holder, V-ring height of the cavity, V-ring position, blank holder force, counter punch force, die clearance, and blanking velocity. Simulation analysis was conducted using the L18 (21 × 37) Taguchi orthogonal array experimental combination. The simulation results of the fracture zone depth and die roll zone width were optimized and analyzed as quality objectives using Taguchi’s smaller-the-better design. The analysis results revealed that with fracture zone depth as the quality objective, 0.164 mm was the optimal value, and counter punch force made the largest contribution of 25.89%. In addition, with die roll zone width as the quality objective, the optimal value was 1.274 mm, and V-ring height of the cavity made the largest contribution of 29.45%. Subsequently, this study selected fracture zone depth and die roll zone width as multicriteria quality objectives and used the robust multicriteria optimal approach and Pareto-optimal solutions to perform multicriteria optimization analysis. The results met the industry’s fraction zone depth standard (below 12% of blank thickness) and achieved a smaller die roll zone width.

A Novel Multi-Objective Process Parameter Interval Optimization Method for Steel Production

Customized small batch orders and sustainable development requirements pose challenges for product quality control and manufacturing process optimization for steel production. Building a multi-quality objective process parameter optimization method that converts the original single target optimization into multi-objective interval capability optimization has become a new method to ensure product quality qualification rate and reduce production costs. Aiming at the multi-quality objective control problem of plate products, we proposed a novel multi-objective process parameter interval optimization model (MPPIO) with equipment process control capability and parameter sensitive analysis. The multi-output support vector regression method was used to establish a multi-quality objective prediction model, which was settled as a verification model for the process parameter optimization results based on the particle swarm optimization algorithm (PSO). The process control capability functions of key parameters were fitted based on the real data in production. With these functions, each optimized particle of the classical PSO was converted into the particle beam of the MIPPO. The iteration process was weight controlled by calculating the Morris sensitivity between each input parameter and output index in the multi-quality objective prediction model, and finally the processing control window of each key parameter was determined according to the process parameter optimization results. The experimental results show that the MPPIO model can obtain the optimal parameter optimization results with the maximum processing capacity and meet the customized processing range requirements. The MPPIO model can reduce the difficulty of control and save production costs while ensuring the product properties is qualified.

Blood Safety: On-Site Verification Of The Screening Of HIV, HBV And HCV By Enzyme Linked Immuno-Sorbent Assay (ELISA) Kits From Bio-Rad Laboratories At The “Centre National De Transfusion Sanguine” (CNTS) Of Lomé In Togo

Background: Blood transfusion improves health and saves lives. Safe blood must be ensured for our populations. Quality assurance is a process that includes a set of coordinated activities in order to achieve the quality objective. Compliance with the quality management rules of medical biology laboratories requires verification of methods prior to their use. This study aimed to verify the on-site verification of the performance of the Enzyme Linked Immuno-Sorbent Assay (ELISA) method performed at the serology laboratory of the CNTS of Lomé. Methods: The performance of ELISA method performed at the serology laboratory of CNTS for the diagnosis of HIV, Hepatitis B and C with Bio-Rad Genscreen ULTRA-HIV Ag-Ac, Bio-Rad Monolisa-HBs Ag ULTRA and Bio-Rad Monolisa HCV Ag-Ac ULTRA V2 kits respectively was evaluated on repeatability, reproducibility, sensitivity and specificity according to COFRAC's SH GTA 04 reference. Results: The evaluation of the repeatability and reproducibility of each kit used in the laboratory resulted in compliant Coefficients of Variation (CV) with manufacturers’ ones. Sensitivities obtained with Bio-Rad Monolisa HCV Ag-Ac ULTRA V2, Bio-Rad Monolisa HBs Ag ULTRA and Bio-Rad Genscreen ULTRA HIV Ag-Ac kits were 94.59%, 98.08% and 100% respectively. For specificity tests, we found 86.49% with BIO-Rad Genscreen ULTRA-HIV Ag-Ac kit, 94.34% with Bio-Rad Monolisa HCV Ag-Ac ULTRA V2 kit and 97.37% with Bio-Rad Monolisa-HBs Ag ULTRA. Conclusion: In general, results were compliant except HIV diagnosis specificity. This study appears as a contribution to the establishment of a verification file for ELISA method used at the serology laboratory of CNTS of Lomé.

Numerical Simulation and Optimization of Fine-Blanking Process for Copper Alloy Sheet

When the fine-blanking process is used, secondary grinding or processing can be omitted because the shear surface of fine-blanking parts can achieve almost zero fracture zone requirements. Fine-blanking has the advantages of high precision and high production efficiency. It was originally used on watch parts, but with increasingly refined technology, it has been widely applied in computers, consumer electronics, communication products, and vehicle parts. The primary objective of the fine-blanking process is to reduce the fracture zone depth and die roll zone width. This study used a 2.5mm thick central processing unit (CPU) thermal heat spreader as an example. Finite element analysis software was employed to simulate and optimize the main eight process parameters that affect the fracture zone depth and die roll zone width after fine-blanking: the V-ring shape angle, V-ring height of the blank holder, V-ring height of the cavity, V-ring position, blank holder force, counter punch force, die clearance, and blanking velocity. Simulation analysis was conducted using the L18 (21×37) Taguchi orthogonal array experimental combination. The simulation results of the fracture zone depth and die roll zone width were optimized and analyzed as quality objectives using Taguchi’s smaller-the-better design. The analysis results revealed that with fracture zone depth as the quality objective, 0.164 mm was the optimal value, and counter punch force made the largest contribution of 25.89%. In addition, with die roll zone width as the quality objective, the optimal value was 1.274 mm, and V-ring height of the cavity made the largest contribution of 29.45%. Subsequently, this study selected fracture zone depth and die roll zone width as multi-criteria quality objectives and used the robust multi-criteria optimal approach and Pareto-optimal solutions to perform multi-criteria optimization analysis. The results revealed the optimal fracture zone depth and die roll zone width were 0.239 mm and 1.288 mm, respectively. Finally, the experimental results verified that the fracture zone depth was 0.230 mm and die roll zone width was 1.205 mm. The findings met the industry’s fraction zone depth standard (below 12% of blank thickness) and achieved a smaller die roll zone width.

Interior Sound Field Subjective Evaluation Based on the 3D Distribution of Sound Quality Objective Parameters and Sound Source Localization

Controlling low frequency noise in an interior sound field is always a challenge in engineering, because it is hard to accurately localize the sound source. Spherical acoustic holography can reconstruct the 3D distributions of acoustic quantities in the interior sound field, and identify low-frequency sound sources, but the ultimate goal of controlling the interior noise is to improve the sound quality in the interior sound field. It is essential to know the contributions of sound sources to the sound quality objective parameters. This paper presents the mapping methodology from sound pressure to sound quality objective parameters, where sound quality objective parameters are calculated from sound pressure at each specific point. The 3D distributions of the loudness and sharpness are obtained by calculating each point in the entire interior sound field. The reconstruction errors of those quantities varying with reconstruction distance, sound frequency, and intersection angle are analyzed in numerical simulation for one- and two-monopole source sound fields. Verification experiments have been conducted in an anechoic chamber. Simulation and experimental results demonstrate that the sound source localization results based on 3D distributions of sound quality objective parameters are different from those based on sound pressure.

UK surface NO₂ levels dropped by 42 % during the COVID-19 lockdown: impact on surface O₃

We report changes in surface nitrogen dioxide (NO2) across the UK during the COVID-19 pandemic when large and rapid emission reductions accompanied a nationwide lockdown (23 March–31 May 2020, inclusively), and compare them with values from an equivalent period over the previous 5 years. Data are from the Automatic Urban and Rural Network (AURN), which forms the basis of checking nationwide compliance with ambient air quality directives. We calculate that NO2 reduced by 42 %±9.8 % on average across all 126 urban AURN sites, with a slightly larger (48 %±9.5 %) reduction at sites close to the roadside (urban traffic). We also find that ozone (O3) increased by 11 % on average across the urban background network during the lockdown period. Total oxidant levels (Ox=NO2+O3) increased only slightly on average (3.2 %±0.2 %), suggesting the majority of this change can be attributed to photochemical repartitioning due to the reduction in NOx. Generally, we find larger, positive Ox changes in southern UK cities, which we attribute to increased UV radiation and temperature in 2020 compared to previous years. The net effect of the NO2 and O3 changes is a sharp decrease in exceedances of the NO2 air quality objective limit for the UK, with only one exceedance in London in 2020 up until the end of May. Concurrent increases in O3 exceedances in London emphasize the potential for O3 to become an air pollutant of concern as NOx emissions are reduced in the next 10–20 years.

UK surface NO₂ levels dropped by 42 % during the COVID-19 lockdown: impact on surface O₃

We report changes in surface nitrogen dioxide (NO2) across the UK during the COVID-19 pandemic when large and rapid emission reductions accompanied a nationwide lockdown (23rd March–31st May, 2020, inclusively), and compare them with values from an equivalent period over the previous five years. Data are from the Automatic Urban and Rural Network (AURN) that form the basis of checking nationwide compliance with ambient air quality directives. We calculate that NO2 reduced by 42 % on average across all 126 urban AURN sites, with a slightly larger (48 %) reduction at sites close to the roadside (urban traffic). We also find that ozone (O3) increased by 11 % on average across the urban background network during the lockdown period. Total oxidant levels (Ox = NO2 + O3) increased only slightly on average (3 %), suggesting the majority of this change can be attributed to photochemical repartitioning due to the reduction in NOx. Generally, we find larger, positive Ox changes in southern UK cities which we attribute to increased UV radiation and temperature in 2020 compared to previous years. The net effect of the NO2 and O3 changes is a sharp decrease in exceedances of the NO2 air quality objective limit for the UK, with only one exceedance in London in 2020 up until the end of May. Concurrent increases in O3 exceedances in London emphasize the potential for O3 to become an air pollutant of concern as NOx emissions are reduced in the next 10–20 years.

ENGINEERING HARMONY UNDER MULTI-CONSTRAINT OBJECTIVES: THE PERSPECTIVE OF META-ANALYSIS

Harmony is the process of coordinated development between the elements, subsystems and the environment in each Engineering stage of the engineering implementation. Quality, duration, cost and risk are the key factors to achieve engineering harmony. Clarifying the influencing factors of engineering harmony and its mechanism can improve the possibility of success. The meta-analysis method is used to carry out a restudy of existing researches of engineering harmony. First, quality, duration, cost and risk are selected as the variables of achieving engineering harmony. Second, the paper collects 29 existing researches including many countries and regions around the world on the relationship between the variables and engineering harmony. Third, each value is calculated and corrected according to literature coding. Forth, publication deviation and total effect test are checked. Finally, the research conclusions and engineering management implications are given based on the results of meta-analysis. The results show that quality objective, duration objective, cost objective and risk management objective all have positive impact on achieving engineering harmony. The engineering type has no regulatory effect on positive impact of the duration objective and cost objective, but has regulatory effect on positive impact of the quality objective and risk management objective on the engineering harmony.

The Songs We Sing: A Textual Analysis of Popular Congregational Songs of the 20th and 21st Century

Contemporary worship songs have been the subject of criticism over their lyrical quality. Objective assessment of the veracity of the criticisms has been difficult to achieve. This research seeks to address this issue by performing a textual analysis of the most popular hymns of the 19th and 20th centuries and contemporary popular worship songs and comparing the results. The research concludes that although there are differences in the lyrical content they are not crucial and that both contemporary worship songs and traditional hymns should find a home in congregational song.